The Regiochemistry of Cyclization of α-Sulfenyl-, α-Sulfinyl-, and α-Sulfonyl-5-hexenyl Radicals: Procedures Leading to Regioselective Syntheses of Cyclic Sulfones and Sulfoxides
作者:Ernest W. Della、Sean D. Graney
DOI:10.1021/jo0497306
日期:2004.5.1
quantities of 6-endo product, the α-sulfinyl species cyclizes with high selectivity (95.5:4.5) via a 5-exo mode. By contrast, ring closure of the 5-methyl-5-hexenyl radicals is found to give substantially the 6-endo product in all cases. It is the α-sulfonyl-5-methyl-5-hexenyl radical that now exhibits high regioselectivity (97.5:2.5) for 6-endo closure: an illustration of the synthetic value of this observation
对α-亚磺酰基-,α-亚磺酰基-和α-磺酰基-5-己烯基和5-甲基-5-己烯基的环化研究表明,该基团的闭环方式具有独特的反差。在5-己烯基的情况下,亚磺酰基取代的物质相对于其类似物显示出意外的区域选择性。因此,虽然α-S-和α-SO 2 -5-己烯基的基团,得到6-可测量和增加数量内的产品,以高选择性(95.5:4.5)的α -亚磺酰物种经由环化的5-外切模式。相比之下,发现5-甲基-5-己烯基的闭环基本上给出了6-内所有情况下的产品。现在,对于6-内膜封闭,具有高区域选择性(97.5:2.5)的是α-磺酰基-5-甲基-5-己烯基:该观察值的合成的例证是模型环己基砜的独立合成61高产。已经发现,在所有情况下,在所采用的条件下均不可逆地发生闭环。