Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031, United States.
J Org Chem. 2012 Oct 5;77(19):8417-27. doi: 10.1021/jo300971w. Epub 2012 Sep 24.
Metalation-electrophilic fluorination of TMS- and TIPS-protected 1,3-benzothiazol-2-yl (BT) propargyl sulfones gave corresponding BT fluoropropargyl sulfones, Julia-Kocienski reagents for the synthesis of fluoro enynes. Both reagents reacted with aldehydes under mild DBU- or LHMDS-mediated conditions, giving high yields of conjugated fluoro enynes with E-stereoselectivity. In comparison to DBU-mediated reactions, stereoselectivity was higher in low-temperature LHMDS-mediated reactions. Two ketones were shown to react as well, using LHMDS as base. In situ removal of the TMS group gave terminal conjugated 2-fluoro 1,3-enynes. Synthetic utility of the fluoro enynes was demonstrated by conversion to internal alkynes and to stereoisomeric fluoro dienes via Sonogashira and Heck couplings.
TMS-和 TIPS 保护的 1,3-苯并噻唑-2-基（BT）丙炔基砜的金属化-亲电氟化生成相应的 BT 氟丙炔基砜，这是合成氟代烯炔的 Julia-Kocienski 试剂。这两种试剂在温和的 DBU-或 LHMDS 介导条件下与醛反应，以高收率得到具有 E-立体选择性的共轭氟代烯炔。与 DBU 介导的反应相比，低温 LHMDS 介导的反应具有更高的立体选择性。使用 LHMDS 作为碱，两种酮也可以反应。通过原位脱除 TMS 基团得到末端共轭 2-氟-1,3-烯炔。通过 Sonogashira 和 Heck 偶联反应将氟代烯炔转化为内部炔烃和立体异构的氟代二烯，证明了氟代烯炔的合成实用性。
