Irradiation of alpha-iodocycloalkanones bearing an allenyl side chain with a sunlamp effected atom-transfer cyclization to give cyclized products in good yield. A mechanism, involving radical atom-transfer cyclization accompanied by 1,5- and 1,4-hydrogen transfers, is proposed.
Cyclizations of ω-allenyl organometallic reagents
作者:Jack K. Crandall、Timothy A. Ayers
DOI:10.1016/s0040-4039(00)79080-0
日期:1992.9
Allenyl organometallic reagents of type R2C = C = CH(CH2)nCH2M undergo cyclization at the central allenic carbon for n = 2 (M = Li) and at the near allenic carbon for n = 3 (M = CuCNLi) to provide cyclopentane systems; little cyclization was observed for the n = 4 systems (M = Li, CuCNLi).
10.1021/jacs.4c05629
作者:Chang, Chieh-Yu、Aponick, Aaron
DOI:10.1021/jacs.4c05629
日期:——
A highlyregio- and enantioselective hydrosulfonylation using commercially available sodium sulfinates is reported, providing the first direct asymmetric rhodium-catalyzed hydrosulfonylation of allenes/alkynes to synthesize chiral allylic sulfones. Ligand screening studies demonstrated the indispensable role of the C1-symmetric P,N-ligand (Rax,S,S)-StackPhim for achieving both high regioselecitivity
据报道,使用市售亚磺酸钠进行高度区域和对映选择性氢磺酰化,提供了第一个直接不对称铑催化的丙二烯/炔烃氢磺酰化,以合成手性烯丙砜。配体筛选研究证明了C 1 -对称 P,N-配体 ( R ax , S , S )-StackPhim 对于实现高区域选择性 (>20:1) 和对映选择性 (高达 97% ee) 的不可或缺的作用。值得注意的是,操作简单的方法和温和的条件允许快速制备具有广泛官能团的手性烯丙基砜。此外,使用叔丁基二甲基甲硅烷氧基甲亚磺酸钠可以在受保护的羟甲基产物的简单转化后集体合成各种手性砜衍生物。