“Sweet Silicones”:  Biocatalytic Reactions to Form Organosilicon Carbohydrate Macromers

Abstract

Immobilized lipase B from Candida antarctica (Novozyme 435) catalyzed the regioselective formation of ester bonds between organosilicon carboxylic diacids and a C1-O-alkylated sugar under mild reaction conditions (i.e., low temperature, neutral pH, solventless). Specifically, the acid-functionalized organosilicones reacted with the primary hydroxyl group at the C6 position of alpha,beta-ethyl glucoside during the regioselective esterification. The pure organosilicon-sugar conjugates were prepared in a one-step reaction without protection-deprotection steps and without activation of the acid groups with the integrity of the siloxane bonds. [reaction: see text]

Organosilicon Biotechnology

“…19) [112,113]. The lipase-mediated esterification was regioselective, preferentially forming the ester with the primary alcohol in greater than 98% regioselectivity as determined from the 13 C DEPT NMR data.…”

“…Chemically, Si-C bonds are typically formed through the Direct Process (on an industrial scale), hydrosilylation reactions between Si-H containing compounds Fig. 19 The selective esterification of α,β-ethylglucoside with carboxypropyl-terminated polydimethylsiloxane [112,113] and alkenes or alkynes, the use of organolithium reagents, Grignard reagents, reductive coupling with alkenes and alkynes via radical anions, and Birch reductions of aromatic molecules in the presence of chlorosilanes. The common theme permeating these methods is their dependence on an alkali or transition metal catalysts.…”

Carbohydrate‐Modified Silicone Surfactants

“…Sahoo et al [41] synthesized glycoside-modified siloxane (Scheme 15) by esterification between organosilicon carboxylic diacids and a C1-O-alkylated sugar by using Novozyme 435 as a catalyst under mild reaction conditions (i.e., low temperature, neutral pH, solventless). Specifically, the acid-functionalized organosilicones reacted with the primary hydroxyl group at the C6 position of a,b-ethyl glucoside during the regioselective esterification.…”

The Boundary Layer as Reaction Compartment for the Synthesis of Hydroxyalkyl-functionalized Siloxanes

“…In principle, enzymatic reactions in organic media and in silicones have been established [6]. Another area of application are two-phase systems, where the starting material is only slightly soluble in water.…”