作者:Stephen Hanessian、Thilo Focken、Rupal Oza
DOI:10.1016/j.tet.2011.09.069
日期:2011.12
A methodology is described for the synthesis of 2,6-disubstituted dihydro[2H]pyrans through a Lewis-acid catalyzed 6-endo-trig cyclization of β-hydroxy-γ,δ-unsaturated alcohols. Employing alkyl-substituted allylic diols and catalytic amounts of a Lewis acid, such as BF3·OEt2, the corresponding syn-pyrans are formed highly diastereoselectively and in good yields. The described process is simple to execute
甲方法是对2,6-二取代的二氢的合成中所述[2 ħ ]通过路易斯酸催化的吡喃6-内- trig的β羟基- γ,δ-不饱和醇的环化。利用烷基取代的烯丙基二醇和催化量的路易斯酸,例如BF 3 ·OEt 2,以高非对映选择性和高收率形成相应的顺式吡喃。所描述的过程易于执行,在环境温度下易于进行,并且可扩展。