DMAP-Organocatalyzed <i>O</i>-Silyl-<i>O</i>-(or <i>C</i>-)-Benzoyl Interconversions by Means of Benzoyl Fluoride
作者:Vincent Levacher、Thomas Poisson、Vincent Dalla、Cyril Papamicaël、Georges Dupas、Francis Marsais
DOI:10.1055/s-2007-968028
日期:2007.2
A mild and efficient transprotection of alcohols from silyl ethers 1a-f to benzoates 2a-f is reported in fair to good yields (50-98%). This silyl-acyl exchange reaction proceeds readily in acetonitrile at room temperature in the presence of benzoyl fluoride and DMAP as an acyl transfer catalyst. A two-step ‘one-pot’ DMAP-catalyzed silylcyanation-transprotection sequence which gives the corresponding O-benzoyl cyanohydrines 2g-l in high yields (72-98%) from various benzaldehyde and ketone derivatives is also reported. This original organocatalytic acyl transfer process was also found to be effective in the O-benzoylation of trimethysilyl enolates 1m-o, providing enol esters 2m-o. Lastly, the potential of this strategy is also illustrated by a DMAP-mediated Claisen condensation between ketene silyl acetals 1p-r and benzoyl fluoride.
本文报道了一种温和且高效的硅醚保护的醇(1a-f)向苯甲酸酯(2a-f)的转化反应,产率良好至优秀(50-98%)。该硅基-酰基交换反应在室温下,以乙腈为溶剂,在苯甲酰氟和DMAP作为酰基转移催化剂的存在下易于进行。同时,还报道了一种两步“一步法”DMAP催化硅氰化-转移保护序列,从各种苯甲醛和酮衍生物得到相应的O-苯甲酰氰醇(2g-l),产率高达72-98%。这种原创的有机催化酰基转移过程在O-苯甲酰化三甲基硅烯醇盐(1m-o)中同样有效,生成烯醇酯(2m-o)。最后,通过DMAP介导的烯酮硅缩醛(1p-r)与苯甲酰氟的Claisen缩合反应,也展示了该策略的应用潜力。