Consequences of the Preeminent Reactivity of 2-OH in Sucrose: Cyclic Acetalation at 2-OH and 3-OH under Basic Conditions

Abstract

The reaction of unprotected sucrose with tert‐butyl chloromethyl ketone in dimethylformamide was investigated as a model for the study of the relative reactivity of the various hydroxy groups of sucrose. Besides the monoethers arising from the substitution of the chlorine atom by 2‐OH and 1′‐OH of sucrose, the major product is a tert‐butyl hydroxymethyl 5‐membered ring acetal involving 2‐OH and 3‐OH. The formation of this product illustrates the preeminent reactivity of 2‐OH towards the carbonyl group of the α‐chloromethyl ketone, leading to an intermediate hemiacetalic anion, which can enter by intramolecular acetal formation through an intermediate epoxide.

Use of Unmodified Carbohydrate Reagents for the Polymerization of Dicyanoalkenes and Dicyanoarenes

“…This might also be applicable to polymerization of 1 with sucrose, not a reducing sugar. The 2-OH position on sucrose is the most reactive in nucleophilic additions . These experiments contrast sharply with others reported 14,15 in reactions of 2b with sugars and alkali.…”

“…The 2-OH position on sucrose is the most reactive in nucleophilic additions. 18 These experiments contrast sharply with others reported 14,15 in reactions of 2b with sugars and alkali. In those experiments, mixtures of cyclotetramer (yields up to 25%) and an oligomer revealing reaction at one cyano group (yields up to 55%) are obtained.…”

Selective Synthesis of 4,6-O-Alkenylidene and -Benzylidene Acetals from Unprotected Sucrose by Lanthanide(III) Resin-Catalyzed Transacetalization

“…Sucrose can provide acetals by acid-catalyzed reaction with dimethoxyalkanes or methoxyalkenes (4,6-O-acetals), [5][6] or under basic conditions with benzylidene dihalides (4,6-O-acetals) 7 or achloromethylketones (2,3-O-acetals). 8 The lanthanide cation salts, known to be compatible with alcoholic (and even aqueous) media, 3,9 were compared with other acidic catalysts, with respect to the preservation of both the disaccharidic structure and the non-carbohydrate moiety, especially in the particular case of a,b-unsaturated dialkyl acetals which exhibit sufficient reactivity under mild acidic conditions. 10,11 The procedure described by Yu et al 3 was followed for the preparation of three lanthanide cation exchange resins, using lanthanum, ytterbium and erbium salts.…”

Reactions of Aldehydes and Ketones and Their Derivatives

“…Diazidooxopropyl acetal (1) undergoes rhodium(II)-catalysed ring expansion to (3) in the presence of TMS chloride; 2 the latter reagent acts as a Lewis acid-base catalyst for ring expansion of the oxonium ylid intermediate (2).…”

“…3 The results are part of a study of the relative reactivities of the hydroxy groups of (unprotected) sucrose.…”