Zinc-mediated domino elimination–alkylation of methyl 5-iodopentofuranosides: an easy route to unsaturated carbohydrates for transition metal-catalyzed carbocyclizations
Zinc-mediated domino elimination–alkylation of methyl 5-iodopentofuranosides: an easy route to unsaturated carbohydrates for transition metal-catalyzed carbocyclizations
5-Iodopentofuranosides are converted with zinc and allyl/propargyl bromide into dienes/enynes which are further used in carbohydrate annulation reactions.
5-碘代呋喃糖苷与锌和烯丙基/丙炔基溴化物反应生成二烯/炔,后者进一步用于碳水化合物环化反应。
Carbohydrate Carbocyclization by a Zinc-Mediated Tandem Reaction and Ring-Closing Enyne Metathesis
作者:Carina Storm Poulsen、Robert Madsen
DOI:10.1021/jo0200062
日期:2002.6.1
Methyl 5-deoxy-5-iodo-pentofuranosides are reductively ring-opened and propargylated in a tandem fashion in the presence of zinc. The 1,7-enynes thus obtained are subjected to ring-closing enyne metathesis with catalyst B to produce functionalized 1-vinyl cyclohexenes. By adding BnNH(2) to the tandem reaction, an amino group can be introduced in the 1,7-enyne products. Addition of 2-TMS-ethynylcerium(III)
Carbohydrate Carbocyclization by a Novel Zinc-Mediated Domino Reaction and Ring-Closing Olefin Metathesis
作者:Lene Hyldtoft、Robert Madsen
DOI:10.1021/ja001415n
日期:2000.9.1
is described using two consecutive organometallic transformations: a novel zinc-mediated domino reaction to give functionalized dienes followed by ring-closing olefin metathesis. In the first reaction, methyl ω-deoxy-ω-iodo glycosides undergo reductive elimination with zinc to produce a terminal double bond. This also liberates the aldehyde which is immediately alkylated in situ by various organozinc