And molecular pdf rearrangement catalysed base acid

Home » Mahikeng » Acid and base catalysed molecular rearrangement pdf

Mahikeng - Acid And Base Catalysed Molecular Rearrangement Pdf

in Mahikeng

The Mechanisms of Amide Hydrolysis MacSphere Home

acid and base catalysed molecular rearrangement pdf

Oxidation and Rearrangement Reactions of Condensed Tannins. 13.04.2004 · Ketonic decarboxylation is a very old reaction that transforms two carboxylic acids into a ketone or a dicarboxylic acid into a cyclic ketone, in particular adipic acid into cyclopentanone. Herein it is reported that catalytic amounts of weak bases such as sodium carbonate can …, Pinacol Rearrangement. In the conversion that gave its name to this reaction, the acid-catalyzed elimination of water from pinacol gives t-butyl methyl ketone. Mechanism of the Pinacol Rearrangement. This reaction occurs with a variety of fully substituted 1,2-diols, and can be understood to involve the formation of a carbenium ion intermediate.

Benzilic Acid Rearrangement

Molecules Free Full-Text The Molecular Design of. Catalysis of the Quadricyclane to Norbornadiene Rearrangement by SnCl2 and CuSO4 mechanism of the rearrangement to a classical Lewis acid-base process. the Quadricyclane to Norbornadiene, over that of neutral formamide. Both the acid catalyzed reaction with nitrogen protonation and the base enhanced hydrolysis reactions proceed without a barrier with respect to reactants and products. The acid catalyzed hydrolysis with protonation on the oxygen atom proceeds with a moderate activation.

Typically, Оµ-caprolactam is produced from cyclohexanone oxime by the acid-catalysed Beckmann rearrangement. The Beckmann rearrangement is a classic, organic transformation in which an oxime is converted into an amide through acid catalysis . Where a cyclic oxime substrate is used, a cyclic amide, or lactam, is formed. Benzilic Acid Rearrangement Supplementary Material Experimental notes This experiment aims at the preparation of 2-hydroxy-2-phenylbenzylic acid from benzil through a molecular rearrangement in basic medium. The experiment is very simple and adequate for 1st year chemistry students.

reactions can be catalysed either by acids or bases. The acid catalysed hydrolysis reactions are also symmetric, meaning that it is only necessary to reverse the steps to get the mechanism for esterification.But hydrolysis is usually favoured by base catalysis, because the acid formed is removed as 16.4 ELECTROPHILIC AROMATIC SUBSTITUTION REACTIONS OF BENZENE 755 Step 2 Reaction of the benzene p electrons with the electrophile to form a carbocation inter- mediate. (Notice that either of the oxygens can accept the electron pair.) Step 3 Loss of a proton from the carbocation to give a new aromatic compound. Nitration is the usual way that nitro groups are introduced into aromatic rings.

Effect of various acids at different concentrations on the pinacol rearrangement Monica De Lezaeta, aWajiha Sattar, Ratio of pinacolone to various alkenes in the absence of added conjugate base Acid Measured quantity 2M 4M 6M molecular iodine as a byproduct. over that of neutral formamide. Both the acid catalyzed reaction with nitrogen protonation and the base enhanced hydrolysis reactions proceed without a barrier with respect to reactants and products. The acid catalyzed hydrolysis with protonation on the oxygen atom proceeds with a moderate activation

Although the aromatic aza-Claisen rearrangement is a general strategy for accessing substituted aromatic amines, there are no highly enantioselective examples of this process. We report the first Brønsted acid catalyzed enantioselective indole aza-Claisen rearrangement for the synthesis of chiral 3-amino-2-substituted indoles. We present evidence for an arene CH–O interaction as a source of Typically, ε-caprolactam is produced from cyclohexanone oxime by the acid-catalysed Beckmann rearrangement. The Beckmann rearrangement is a classic, organic transformation in which an oxime is converted into an amide through acid catalysis . Where a cyclic oxime substrate is used, a cyclic amide, or lactam, is formed.

Traditionally, it is the acid- or base-catalyzed condensation of one carbonyl compound with the enolate/enol of another, which may or may not be the same, to generate a β-hydroxy carbonyl compound—an aldol. The method is compromised by self- Three examples of an unusual 1,2 alkyl shift from oxygen to carbon, known as the [1,2]-Wittig rearrangement, are shown below. Here a powerful base generates a reactive carbanion alpha to an ether. An intramolecular shift of an alkyl or aryl group then creates a much more stable alkoxide anion, which in the last example eliminates cyanide anion.

Index A Acid/base properties adsorption calorimetry description, 119–126 limitations, 126–128 multifunctional molecular sieves and acid/basic sites, 339–340 Index 351. oxidation and acid/basic sites, 338–339 Fries rearrangement, acid-catalysed gas-phase reactions, 303–304 hydroxyacetophenones (HAP), 302–303 pdf. Mechanism of the Beckmann rearrangement in sulfuric acid solution. Journal of the Chemical Society, Perkin Transactions 2, 1997. Greet Raspoet. Binh Minh Nguyen. Luc G Vanquickenborne. Minh Nguyen. minh nguyen.

Pinacol Rearrangement. In the conversion that gave its name to this reaction, the acid-catalyzed elimination of water from pinacol gives t-butyl methyl ketone. Mechanism of the Pinacol Rearrangement. This reaction occurs with a variety of fully substituted 1,2-diols, and can be understood to involve the formation of a carbenium ion intermediate Pinacol Rearrangement. In the conversion that gave its name to this reaction, the acid-catalyzed elimination of water from pinacol gives t-butyl methyl ketone. Mechanism of the Pinacol Rearrangement. This reaction occurs with a variety of fully substituted 1,2-diols, and can be understood to involve the formation of a carbenium ion intermediate

Lewis acid catalysts (e.g. FeCl 3) catalyze these rearrangements, and the product favored at equilibrium is bornyl chloride. The rearrangement that occurs under base catalyzed elimination conditions reflects the eclipsed configuration of the two-carbon bridge bearing the chlorine atom. Three examples of an unusual 1,2 alkyl shift from oxygen to carbon, known as the [1,2]-Wittig rearrangement, are shown below. Here a powerful base generates a reactive carbanion alpha to an ether. An intramolecular shift of an alkyl or aryl group then creates a much more stable alkoxide anion, which in the last example eliminates cyanide anion.

The Wolff rearrangement has a few retrons, depending on the reaction out of the ketene intermediate. A carboxylic acid derivative with an О±-methylene group is a retron for an Arndt-Eistert type homologation. An acid in which the О±-carbon belongs to a ring is a retron for a Wolff rearrangement ring contraction. The Wolff rearrangement has a few retrons, depending on the reaction out of the ketene intermediate. A carboxylic acid derivative with an О±-methylene group is a retron for an Arndt-Eistert type homologation. An acid in which the О±-carbon belongs to a ring is a retron for a Wolff rearrangement ring contraction.

acid hydrolysis, 240 base hydrolysis, 238 electronic effects in, 237 Grignard reagents, 238 leaving groups and, 237 reduction, 215 steric effects in, 238 tetrahedral intermediates in, 236 Catalysts acid, 42, 74 base, 75 cyanide ion, 231 heterogeneous, 143, 191,264 Lewis acid, … Acid–base reaction - Acid–base reaction - Acid–base catalysis: Acids (including Lewis acids) and bases act as powerful catalysts for a great variety of chemical reactions, in the laboratory, in industry, and in processes occurring in nature. Historically, catalytic action was regarded as one of the essential characteristics of acids, and the parallel occurrence of catalytic action and

02.06.2003 · The lanthanide catalysed para -Claisen–Cope rearrangement has been used as the key step in a short synthesis of the prenylated isoflavone, lupiwighteone. The Mitsunobu reaction was employed for the 5- O -prenylation of the acid/base sensitive acetylated isoflavone to afford the allyl aryl ether precursor, which was then rearranged under mild conditions in good yield. Rearrangement of the Supplementary Information On the selective acid-catalysed dehydration of 1,2,6-hexanetriol Michael R. Nolan, Geng Sun and Brent H. Shanks* pyran rings are always the base peak in their respective MS spectra by a large margin if the molecule undergoes a McLafferty rearrangement, giving up an ethylene fragment (loss of 27) and leaving behind

In summary, we have developed a Lewis acid-catalysed inter-molecular a,a0-annulation of enamines (generated in situ)with alkynyl enones, providing an easy access to bicyclo[3. n.1]alkenones. The corresponding products can b eobtainedinhighyieldsunder benign reaction conditions. Desymmetrization products can be achieved with meso-cyclic reactions can be catalysed either by acids or bases. The acid catalysed hydrolysis reactions are also symmetric, meaning that it is only necessary to reverse the steps to get the mechanism for esterification.But hydrolysis is usually favoured by base catalysis, because the acid formed is removed as

Base catalysed decomposition of anthracene molecular rotors,12 before. If R = Alkynyl (2d), this cleavage Hence, many rearrangement products have been found under thermal conditions.16 Even more difficult is the explanation of AQ (3) formation at room temperature, which we often observe Similarly, the mechanism of alkene cleavage catalysed by extradiol dioxygenase proceeds initially again through an Fe(II)-semiquinone complex, although then diverging to form an Fe(II) proximal hydroperoxide intermediate; the latter undergoes to Criegee rearrangement followed by hydrolysis to afford 2-hydroxymuconaldehyde (Scheme 7 (b)).

Supplementary Information On the selective acid-catalysed dehydration of 1,2,6-hexanetriol Michael R. Nolan, Geng Sun and Brent H. Shanks* pyran rings are always the base peak in their respective MS spectra by a large margin if the molecule undergoes a McLafferty rearrangement, giving up an ethylene fragment (loss of 27) and leaving behind Basicity. Compared to amines, amides are very weak bases.While the conjugate acid of an amine has a pK a of about 9.5, the conjugate acid of an amide has a pK a around −0.5. Therefore, amides don't have as clearly noticeable acid–base properties in water.This relative lack of basicity is explained by the electron-withdrawing nature of the carbonyl group where the lone pair of electrons on

Typically, Оµ-caprolactam is produced from cyclohexanone oxime by the acid-catalysed Beckmann rearrangement. The Beckmann rearrangement is a classic, organic transformation in which an oxime is converted into an amide through acid catalysis . Where a cyclic oxime substrate is used, a cyclic amide, or lactam, is formed. pdf. Co(II) Catalysed Oxidation of О±-Pinene by Molecular Oxygen. Part 2. Tetrahedron, 2000. Ari Koskinen. Marja Lajunen. Tatja Maunula. Ari Koskinen. Marja Lajunen. Tatja Maunula. Download with Google Download with Facebook or download with email.

Effect of various acids at different concentrations on the pinacol rearrangement Monica De Lezaeta, aWajiha Sattar, Ratio of pinacolone to various alkenes in the absence of added conjugate base Acid Measured quantity 2M 4M 6M molecular iodine as a byproduct. reactions can be catalysed either by acids or bases. The acid catalysed hydrolysis reactions are also symmetric, meaning that it is only necessary to reverse the steps to get the mechanism for esterification.But hydrolysis is usually favoured by base catalysis, because the acid formed is removed as

The Wolff rearrangement has a few retrons, depending on the reaction out of the ketene intermediate. A carboxylic acid derivative with an α-methylene group is a retron for an Arndt-Eistert type homologation. An acid in which the α-carbon belongs to a ring is a retron for a Wolff rearrangement ring contraction. of Fries rearrangement, claisen rearrangement, Gatterman synthesis, Hauben-Hoesch reiction, Reimer Tiemann reaction. Ethers and Epoxides Nomenclature of ethers and methods of their formation, physical properties. Chemical reactions- Cleavage and autoxidation, Ziesel’s method. Synthesis of epoxides. Acid and base catalysed ring opening

Pinacol Rearrangement. In the conversion that gave its name to this reaction, the acid-catalyzed elimination of water from pinacol gives t-butyl methyl ketone. Mechanism of the Pinacol Rearrangement. This reaction occurs with a variety of fully substituted 1,2-diols, and can be understood to involve the formation of a carbenium ion intermediate The benzilic acid rearrangement is formally the 1,2-rearrangement of 1,2-diketones to form α-hydroxy–carboxylic acids using a base. This reaction receives its name from the reaction of benzil with potassium hydroxide to form benzilic acid. First performed by Justus von Liebig in 1838, it is the first reported eample of a rearrangement reaction.

(PDF) Co(II) Catalysed Oxidation of О±-Pinene by Molecular

acid and base catalysed molecular rearrangement pdf

Rearrangement. Synthesis of amides using Lewis acid catalyst: Iodine catalyzed Ritter reaction General overview of Lewis acids Acid and base reactions are of tremendous importance in organic chemistry, as they are also in inorganic and biochemistry. In 1884, Svante A. Arrhenius defined Synthesis of amides using Lewis acid catalyst: Iodine catalyzed, 16.10.2018 · Antioxidant enzyme glutathione peroxidase (GPx) decomposes hydroperoxides by utilizing the different redox chemistry of the selenium and sulfur. Here, we report a ….

Polar effects of substituents on the acid- and base. This chapter discusses acid–base catalysis and proton-transfer reactions. Proton-transfer (PT) reactions lie at the heart of the mechanistic definition of acid and base. An acid is a molecular entity capable of donating a proton and a base is another molecular entity with a tendency to accept that proton., Supplementary Information On the selective acid-catalysed dehydration of 1,2,6-hexanetriol Michael R. Nolan, Geng Sun and Brent H. Shanks* pyran rings are always the base peak in their respective MS spectra by a large margin if the molecule undergoes a McLafferty rearrangement, giving up an ethylene fragment (loss of 27) and leaving behind.

Index [link.springer.com]

acid and base catalysed molecular rearrangement pdf

Brønsted Acid Catalyzed Enantioselective Indole Aza. Acid–base reaction - Acid–base reaction - Acid–base catalysis: Acids (including Lewis acids) and bases act as powerful catalysts for a great variety of chemical reactions, in the laboratory, in industry, and in processes occurring in nature. Historically, catalytic action was regarded as one of the essential characteristics of acids, and the parallel occurrence of catalytic action and https://fr.wikipedia.org/wiki/Base_de_Tr%C3%B6ger Acid and base catalysed rearrangements of 9,10-dioxotaxanes (Scheme 2).6 The molecular formulae of 1 and 3 differed for the 727 728 presence of an addmonal water molecule in 3 (C29H36OII). The appearance of C-10 as a lactone carbonyl (8 174.0, s) and C-15 as a deshielded singlet at 8 89.8 showed that 3 had the same lactone-bridged bis.

acid and base catalysed molecular rearrangement pdf


02.06.2003 · The lanthanide catalysed para -Claisen–Cope rearrangement has been used as the key step in a short synthesis of the prenylated isoflavone, lupiwighteone. The Mitsunobu reaction was employed for the 5- O -prenylation of the acid/base sensitive acetylated isoflavone to afford the allyl aryl ether precursor, which was then rearranged under mild conditions in good yield. Rearrangement of the However, migration of a methyl group both stabilizes the cation (it becomes tertiary instead of secondary) and allows E1 elimination of a proton to take place to give a stable alkene. The migration of an alkyl group to a cationic centre is known as a Wagner-Meerwein rearrangement or …

pdf. Mechanism of the Beckmann rearrangement in sulfuric acid solution. Journal of the Chemical Society, Perkin Transactions 2, 1997. Greet Raspoet. Binh Minh Nguyen. Luc G Vanquickenborne. Minh Nguyen. minh nguyen. Typically, Оµ-caprolactam is produced from cyclohexanone oxime by the acid-catalysed Beckmann rearrangement. The Beckmann rearrangement is a classic, organic transformation in which an oxime is converted into an amide through acid catalysis . Where a cyclic oxime substrate is used, a cyclic amide, or lactam, is formed.

16.4 ELECTROPHILIC AROMATIC SUBSTITUTION REACTIONS OF BENZENE 755 Step 2 Reaction of the benzene p electrons with the electrophile to form a carbocation inter- mediate. (Notice that either of the oxygens can accept the electron pair.) Step 3 Loss of a proton from the carbocation to give a new aromatic compound. Nitration is the usual way that nitro groups are introduced into aromatic rings. Traditionally, it is the acid- or base-catalyzed condensation of one carbonyl compound with the enolate/enol of another, which may or may not be the same, to generate a β-hydroxy carbonyl compound—an aldol. The method is compromised by self-

Catalysis of the Quadricyclane to Norbornadiene Rearrangement by SnCl2 and CuSO4 mechanism of the rearrangement to a classical Lewis acid-base process. the Quadricyclane to Norbornadiene Carbonyl Chemistry (12 Lectures) alkenes of similar molecular weight. ВҐAldehydes and ketones are not hydrogen bond donors (they can Г•t donate a proton); therefore, they have lower boiling points than alcohols of similar ВҐThere are other acid- and base-catalyzed examples. 19

30.10.2018 · Acid catalyzed hydration of alkenes involves replacing the pi bond on an alkene with a water molecule. This is done by adding an alcohol to the more substituted carbon atom, and hydrogen to the less substituted carbon atom. This chapter discusses acid–base catalysis and proton-transfer reactions. Proton-transfer (PT) reactions lie at the heart of the mechanistic definition of acid and base. An acid is a molecular entity capable of donating a proton and a base is another molecular entity with a tendency to accept that proton.

Base catalysed decomposition of anthracene molecular rotors,12 before. If R = Alkynyl (2d), this cleavage Hence, many rearrangement products have been found under thermal conditions.16 Even more difficult is the explanation of AQ (3) formation at room temperature, which we often observe over that of neutral formamide. Both the acid catalyzed reaction with nitrogen protonation and the base enhanced hydrolysis reactions proceed without a barrier with respect to reactants and products. The acid catalyzed hydrolysis with protonation on the oxygen atom proceeds with a moderate activation

B-ring quinone-methides may similarly be trapped but are preferentially susceptible to intramolecular trapping to give analogues with rearranged pyran heterocycles. A mechanistic rationale to explain the base-catalyzed rearrangement reactions and the oxidative conversion of B- … 02.06.2003 · The lanthanide catalysed para -Claisen–Cope rearrangement has been used as the key step in a short synthesis of the prenylated isoflavone, lupiwighteone. The Mitsunobu reaction was employed for the 5- O -prenylation of the acid/base sensitive acetylated isoflavone to afford the allyl aryl ether precursor, which was then rearranged under mild conditions in good yield. Rearrangement of the

02.06.2003 · The lanthanide catalysed para -Claisen–Cope rearrangement has been used as the key step in a short synthesis of the prenylated isoflavone, lupiwighteone. The Mitsunobu reaction was employed for the 5- O -prenylation of the acid/base sensitive acetylated isoflavone to afford the allyl aryl ether precursor, which was then rearranged under mild conditions in good yield. Rearrangement of the In summary, we have developed a Lewis acid-catalysed inter-molecular a,a0-annulation of enamines (generated in situ)with alkynyl enones, providing an easy access to bicyclo[3. n.1]alkenones. The corresponding products can b eobtainedinhighyieldsunder benign reaction conditions. Desymmetrization products can be achieved with meso-cyclic

of Fries rearrangement, claisen rearrangement, Gatterman synthesis, Hauben-Hoesch reiction, Reimer Tiemann reaction. Ethers and Epoxides Nomenclature of ethers and methods of their formation, physical properties. Chemical reactions- Cleavage and autoxidation, Ziesel’s method. Synthesis of epoxides. Acid and base catalysed ring opening Carbonyl Chemistry (12 Lectures) alkenes of similar molecular weight. ¥Aldehydes and ketones are not hydrogen bond donors (they can Õt donate a proton); therefore, they have lower boiling points than alcohols of similar ¥There are other acid- and base-catalyzed examples. 19

that of TIJnm1ons and Hawthorne21 • They carried out the acid­ and. base-cata1ysed br•orrdnation of cyclopenty·l phenyl ketone and cyclopentyl-2,2,5,5 :-d 11 _ phenyl ketone in aqueotls acetic acid. at 27°. For both acid.- and base-catalysed x•eacM.ons = (3 Three examples of an unusual 1,2 alkyl shift from oxygen to carbon, known as the [1,2]-Wittig rearrangement, are shown below. Here a powerful base generates a reactive carbanion alpha to an ether. An intramolecular shift of an alkyl or aryl group then creates a much more stable alkoxide anion, which in the last example eliminates cyanide anion.

Base catalysed decomposition of anthracene molecular rotors,12 before. If R = Alkynyl (2d), this cleavage Hence, many rearrangement products have been found under thermal conditions.16 Even more difficult is the explanation of AQ (3) formation at room temperature, which we often observe Request PDF on ResearchGate Citric acid catalysed Beckmann rearrangement, under solvent free conditions Citric acid is reported to be a highly efficient and eco-friendly catalyst for the

Reversal of Anomeric Selectivity with O-Glycosyl Trichloroacetimidates as Glycosyl Donors and Thiols as Acceptors Under Acid/Base Catalysis Amit Kumar[al and Richard R. Schmidt*[a,bl Keywords: Carbohydrates / Glycosylation / Thioglycosylation / Reaction mechanisms Boron trifluoride or trimethylsilyl trifluoromethanesulfonate catalysed the 16.4 ELECTROPHILIC AROMATIC SUBSTITUTION REACTIONS OF BENZENE 755 Step 2 Reaction of the benzene p electrons with the electrophile to form a carbocation inter- mediate. (Notice that either of the oxygens can accept the electron pair.) Step 3 Loss of a proton from the carbocation to give a new aromatic compound. Nitration is the usual way that nitro groups are introduced into aromatic rings.

over that of neutral formamide. Both the acid catalyzed reaction with nitrogen protonation and the base enhanced hydrolysis reactions proceed without a barrier with respect to reactants and products. The acid catalyzed hydrolysis with protonation on the oxygen atom proceeds with a moderate activation The benzilic acid rearrangement is formally the 1,2-rearrangement of 1,2-diketones to form α-hydroxy–carboxylic acids using a base. This reaction receives its name from the reaction of benzil with potassium hydroxide to form benzilic acid. First performed by Justus von Liebig in 1838, it is the first reported eample of a rearrangement reaction.

Base catalysed decomposition of anthracene molecular rotors,12 before. If R = Alkynyl (2d), this cleavage Hence, many rearrangement products have been found under thermal conditions.16 Even more difficult is the explanation of AQ (3) formation at room temperature, which we often observe Carbonyl Chemistry (12 Lectures) alkenes of similar molecular weight. ¥Aldehydes and ketones are not hydrogen bond donors (they can Õt donate a proton); therefore, they have lower boiling points than alcohols of similar ¥There are other acid- and base-catalyzed examples. 19

Index A Acid/base properties adsorption calorimetry description, 119–126 limitations, 126–128 multifunctional molecular sieves and acid/basic sites, 339–340 Index 351. oxidation and acid/basic sites, 338–339 Fries rearrangement, acid-catalysed gas-phase reactions, 303–304 hydroxyacetophenones (HAP), 302–303 Catalysis of the Quadricyclane to Norbornadiene Rearrangement by SnCl2 and CuSO4 mechanism of the rearrangement to a classical Lewis acid-base process. the Quadricyclane to Norbornadiene

In summary, we have developed a Lewis acid-catalysed inter-molecular a,a0-annulation of enamines (generated in situ)with alkynyl enones, providing an easy access to bicyclo[3. n.1]alkenones. The corresponding products can b eobtainedinhighyieldsunder benign reaction conditions. Desymmetrization products can be achieved with meso-cyclic Mechanism of the Fries Rearrangement. The reaction is catalyzed by BrГёnsted or Lewis acids such as HF, AlCl 3, BF 3, TiCl 4 or SnCl 4.The acids are used in excess of the stoichiometric amount, especially the Lewis acids, since they form complexes with both the starting materials and products.

catechinic acid. 1-3 . However, no products have been isolated from the reaction of condensed tannins in alkaline solutions to support this hypothesis. The base-catalysed reactions of polymeric procyanidins were examined because many of their industrial applications involve their dissolution and/or reaction at … reactions can be catalysed either by acids or bases. The acid catalysed hydrolysis reactions are also symmetric, meaning that it is only necessary to reverse the steps to get the mechanism for esterification.But hydrolysis is usually favoured by base catalysis, because the acid formed is removed as

acid and base catalysed molecular rearrangement pdf

16.4 ELECTROPHILIC AROMATIC SUBSTITUTION REACTIONS OF BENZENE 755 Step 2 Reaction of the benzene p electrons with the electrophile to form a carbocation inter- mediate. (Notice that either of the oxygens can accept the electron pair.) Step 3 Loss of a proton from the carbocation to give a new aromatic compound. Nitration is the usual way that nitro groups are introduced into aromatic rings. Acid and base catalysed rearrangements of 9,10-dioxotaxanes (Scheme 2).6 The molecular formulae of 1 and 3 differed for the 727 728 presence of an addmonal water molecule in 3 (C29H36OII). The appearance of C-10 as a lactone carbonyl (8 174.0, s) and C-15 as a deshielded singlet at 8 89.8 showed that 3 had the same lactone-bridged bis