Glucuronic esters. Part IV. Synthesis of 1-O-acyl-D-glucopyranuronic acids via benzyl 1-O-acyl-2,3,4-tri-O-benzyl-D-glucopyranuronates

Abstract

Glucuronic Esters. Part lv. l Synthesis of 1 -0-Acyl-D-glucopyranuronic Acids via Benzyl 1 -0-Acyl-2,3,4-tri-0-benzyl -D-glucopyranuronates t By D. Keglevie," N. PravdiC, and J. TomaSib, Tracer Laboratory, Institute ' Ruder BoSkoviC,' Zagreb, YugoslaviaBenzyl 1 -0-acyl-2,3,4-tri-0-benzyl-D-glucopyranuronates were synthesised by different routes and catalytically debenzylated into 1 -0-acyl-D-glucopyranuronic acids. Both anomers of 1 -0-benzoyl-, 1 -0-p-methoxybenzoyl-, and 1 -0-3',4'-dimethoxybenzoyl-D-glucopyranuronic acids were obtained ; they represent the first known anomeric pairs in this series. Some 1 -0-acyl glucuronic acids were converted into their methyl 2.3.4-tri-O-acetyl derivatives.

Protecting Groups for Glucuronic Acid: Application to the Synthesis of New Paclitaxel (Taxol) Derivatives

“…Another currently used protecting group for the hydroxyls is the benzyl ether. , In the case of glucuronic acid derivatives, the most efficient way was to introduce the benzyl ethers into uronic acid prior to the glucose oxidation stage. However, this method, which avoids the classic 4,5-elimination under basic conditions, presents the inconvenience of adding steps to the synthesis.…”

Synthesis of biliverdin and bilirubin 1-O-acyl-β-d-glucopyranuronic acids

“…rivatives of glucuronic acid yields anomeric mixtures enriched in the a-form, if non-bulky reagents, e.g. acetic anhydride, are used (Keglevic et al, 1968;Compernolle, 1980a,b3. The proportion of fJ-anomer increases by using higher temperatures (Compernolle, 1980a,c) or-sterically more demanding reagents such as mesitoyl chloride or carboxylic acids activated with dicyclohexylcarbodi-imide (Keglevic et al, 1968).…”

“…acetic anhydride, are used (Keglevic et al, 1968;Compernolle, 1980a,b3. The proportion of fJ-anomer increases by using higher temperatures (Compernolle, 1980a,c) or-sterically more demanding reagents such as mesitoyl chloride or carboxylic acids activated with dicyclohexylcarbodi-imide (Keglevic et al, 1968). However, the use of the latter compound as a condensing reagent for bilirubin and biliverdin was unsuccessful, owing to the formation of N-acylureas (Hancock et al, 1976;F.…”

The synthesis of O-glucuronides

“…The ester tricarbonate 63 was prepared 82 by a lengthy sequence from 6 and used to prepare the O-acyl glucuronide of the analgesic acid 64 (Mitsunobu coupling). The corresponding tri-O-benzyl ether conjugate, prepared from a known intermediate, 83 could not be deprotected without reducing the ketone function. Very recently the allyl ester of -glucuronic acid has been successfully coupled to a range of carboxylic acids, again using Mitsunobu conditions, to afford conjugates 65 84 which were deprotected by Pd 0 in the presence of pyrrolidine to afford good yields of the O-acyl -glucuronides.…”