Thaharn Watcharaporn, Soorukram Darunee, Kuhakarn Chutima, Tuchinda Patoomratana, Pakawatchai Chaveng, Saithong Saowanit, Reutrakul Vichai, Pohmakotr Manat
Center of Excellence for Innovation in Chemistry (PERCH-CIC) and Department of Chemistry Faculty of Science, Mahidol University , Rama VI Road, Bangkok 10400, Thailand.
J Org Chem. 2015 Jan 16;80(2):816-27. doi: 10.1021/jo5022579. Epub 2014 Dec 31.
An asymmetric synthesis of gem-difluoromethylenated linear triquinanes is described exploiting the synthetic utilities of PhSCF2TMS (5) as a "(•)CF2(-)'' building block. The strategy involves fluoride-catalyzed nucleophilic addition of PhSCF2TMS (5) to chiral ketocyclopentenes 6 to provide silylated adducts 9 or alcohol derivatives 10 and 11. Subsequent cascade radical cyclization of the gem-difluoroalkyl radical generated from silylated adducts 9 or alcohols 10 and 11 afforded gem-difluoromethylenated linear triquinanes 16 as an approximate 1:1 mixture of two diastereomers (16A and 16B). Alternatively, a convenient asymmetric synthesis of gem-difluoromethylenated linear triquinanes 16A can be accomplished by oxidation of 16a (R = H) to provide ketotriquinane 17 followed by a highly stereoselective nucleophilic addition to 17 employing DIBAL, NaBH4, and various Grignard reagents.
利用PhSCF2TMS（5）作为“(•)CF2(-)”结构单元的合成效用，描述了偕二氟亚甲基化线性三环烷的不对称合成。该策略包括氟化物催化的PhSCF2TMS（5）对手性酮环戊烯6的亲核加成，以提供硅烷化加合物9或醇衍生物10和11。随后，由硅烷化加合物9或醇10和11产生的偕二氟烷基自由基进行级联自由基环化，得到偕二氟亚甲基化线性三环烷16，为两种非对映异构体（16A和16B）的近似1:1混合物。或者，偕二氟亚甲基化线性三环烷16A的便捷不对称合成可通过将16a（R = H）氧化以提供酮三环烷17，然后使用DIBAL、NaBH4和各种格氏试剂对17进行高度立体选择性亲核加成来实现。
