Sulfanyl radical addition-addition-cyclization (SRAAC) of unbranched diynes proceeded smoothly to give cyclized exo-olefins, while the sulfanyl radical addition-cyclization-addition (SRACA) of diynes having a quaternary carbon gave cyclized endo-olefins. This method was successfully applied to the synthesis of A-ring fragment of 1α, 25-dihydroxyvitamin D3.
无支链二炔的
硫基自由基加成-加成-环化 (SR
AAC) 反应顺利进行,生成环状外烯烃,而具有季碳的二炔的
硫基自由基加成-环化-加成 (SRACA) 反应则生成环状内烯烃。这一方法成功应用于1α, 25-二羟基
维生素D3的A环片段的合成。