Regioselective Alkylation of Carbohydrate Derivatives Catalyzed by a Diarylborinic Acid Derivative
作者:Lina Chan、Mark S. Taylor
DOI:10.1021/ol200990e
日期:2011.6.17
Regioselective, catalyst-controlled monoalkylations of cis-vicinal diol motifs in carbohydrate derivatives, using a diphenylborinic ester precatalyst, are described. Selective installation of benzyl, naphthylmethyl, 4-bromobenzyl and benzyloxymethyl protective groups at a single secondary hydroxy group of ten representative carbohydrate derivatives illustrates the scope of this method. This new mode
mechanism is proposed to proceed via a cyclic dioxolane‐type intermediate, formed between the iron(III) species and two adjacent hydroxyl groups. This approach represents the first transition‐metal catalysts that are able to replace stoichiometric amounts of organotin reagents in regioselectivealkylation. The reactions generally lead to very high regioselectivities and high yields, on par with, or better