Carbohydrate derivatives 1a, 1b, 3a and 3b have been subjected to copper(I) catalysed photoannulation to produce tetracyclic products 2a, 2b, 4a and 4b respectively as single enantiomers. The same reaction carried out on substrates 5a and 5b leads stereoselectively to the spiro products 6a and 6b respectively. Photoannulation of substrate 7 gave an approximate 1 : 1 mixture of spiro products 8 and 9. A mechanistic rationalisation of these results is proposed.
碳水化合物衍
生物 1a、1b、3a 和 3b 在
铜(I)催化的光annulation 作用下,分别生成四环产物 2a、2b、4a 和 4b 的单对映体。对底物 5a 和 5b 进行同样的反应,可分别立体选择性地生成螺环产物 6a 和 6b。对底物 7 进行光诱导,可得到近似 1 : 1 的螺产物 8 和 9 的混合物。本文提出了这些结果的机理。