金属单质锡促进的水相中醛的Barbier类型炔丙基化反应

报道了一种简单、 高效且快速的醛的炔丙基化反应体系. 使用廉价的金属单质锡粉, 在路易斯酸SnCl₂·2H₂O促进下, 实现了水相中醛羰基化合物的Barbier类型炔丙基化反应, 高收率、高区域选择性地得到单一的高炔丙基醇产物(收率99%). 该方法具有底物适用范围广、反应条件温和(30℃)、环境友好(以水为介质)及反应速度快(30 min内反应原料基本消失)等优点. 另外, 在使用肉桂醛为底物且将反应温度升至55℃时, 意外地得到了中等收率的新型高度对称的烯炔醚化合物.

Barbier-type Propargylation of Aldehyde in Aqueous Media Promoted by Metal Tin

Carbonyl propargylation or allenylation by 3-haloprop-1-yne with metal or metal salts is one of the most convenient methods for introduction of propargyl(prop-2-ynyl) or allenyl functions which can be transformed into natural products and pharmaceutical intermediates. Currently, the Barbier-type propargylation of aromatic adehydes mainly focuses on the active metal indium or its salt, and the solvents used are generally THF or THF/H2O mixture. In comparison, there are a few reports about the propargylation of carbonyl compounds promoted by metal tin or its salts in pure water. Additionally, due to the reaction regioselectivity, there are two competitive products such as homopropargylic alcohol and allenyl alcohol. Hence, it is worth to explore the highly efficient protocol for the preparation of single product. Based on our work on the allylation of carbonyl compounds and the application of homopropargylic alcohol, we herein attempt to study the propargylation of carbonyl compound so as to conveniently obtain excellent yields of homopropargylic alcohol which is used as the further reaction substrate. Therefore, this paper reported a simple, highly efficient and fast protocol for the propargylation of aldehyde. Namely, employing inexpensive metal tin powder, the Barbier-type propargylation of aldehydes can be achieved with the Lewis acid SnCl2·2H2O as additive, and then affording the single homopropargylic alcohol with high yields and high regioselectivity(up to 99% yield). Moreover, this methodology had some obvious advantages such as broad substrates applicability, mild reaction condition(30℃), environmentally benign(water media), rapid(the reaction raw materials can nearly disappear in 30 min) and so on. In addition, in the case of cinnamic aldehyde substrate, a novel enyne ether with highly symmetric structure was unexpectedly obtained when the reaction was carried out at an increasing temperature of 55℃.