通过羟基辅助剂在经由自由基环化合成吡咯烷过程中的非对映体控制。
Diastereocontrol by a hydroxyl auxiliary in the synthesis of pyrrolidines via radical cyclization.
作者信息
Besev Magnus, Engman Lars
机构信息
Uppsala University, Institute of Chemistry, Department of Organic Chemistry, Box 531, Sweden.
出版信息
Org Lett. 2002 Sep 5;4(18):3023-5. doi: 10.1021/ol026038t.
[reaction: see text] Organoselenium precursors of 3-aza-5-hexenyl radicals carrying a 1-hydroxyalkyl group in the 2-position were prepared by addition of organometallic reagents to N-allyl-2-aziridinecarbonitrile, reduction of the resulting aziridine ketone, and regioselective benzeneselenol ring opening of the aziridine. Reductive radical cyclization was highly selective, affording the corresponding trans-2,4-disubstituted pyrrolidine (cis/trans ca. 1/10) as the major diastereomer. Recrystallization afforded material that was substantially more enriched in the trans isomer (cis/trans < 1/25).
[反应：见正文] 2-位带有1-羟烷基的3-氮杂-5-己烯基自由基的有机硒前体，是通过将有机金属试剂加成到N-烯丙基-2-氮丙啶腈上、还原所得的氮丙啶酮以及对氮丙啶进行区域选择性苯硒醇开环反应制备的。还原自由基环化反应具有高度选择性，主要非对映异构体为相应的反式-2,4-二取代吡咯烷（顺式/反式约为1/10）。重结晶得到的产物中反式异构体的富集程度显著更高（顺式/反式<1/25）。
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