113705-06-9Relevant academic research and scientific papers
Reaction of a Cyclic Phosphonium Ylide with α,α-Unsaturated Thioesters
Kishimoto, Narumi,Fujimoto, Tetsuya,Yamamoto, Iwao
, p. 5988 - 5992 (1999)
The tandem Michael-intramolecular Wittig reactions of a five-membered cyclic phosphonium ylide (2) with α,α-unsaturated thioesters afforded cycloheptene derivatives 4a-g in 29-58% yield. The reaction proceeded via a rigid phosphabicyclic intermediate and supplied the cycloheptene derivatives with high stereoselectivity. On the other hand, although the reaction using S-cyclohexyl cyclopentenethiocarboxylate 5a as a substrate gave a 1:1 mixture of cis and trans adducts of the corresponding hydroazulene derivatives, the reaction of S-tert-butyl cyclopentenethiocarboxylate 5b gave cis-adduct as a major product (cis:trans =17:3).
Diastereoselective tandem Michael-intramolecular Wittig reactions of a cyclic phosphonium ylide with 8-phenylmenthyl enoates
Nagao,Suenaga,Ichihashi,Fujimoto,Yamamoto,Kakehi,Iriye
, p. 890 - 893 (2007/10/03)
The diastereoselective tandem Michael-intramolecular Wittig reactions of a five-membered cyclic phosphonium ylide 2 using 8-phenylmenthyl enoates were examined. The reaction of the phosphonium ylide with 8-phenylmenthyl cinnamate followed by the hydrolysis of the resulting enol ether 4a afforded (3R,4S)-4-(diphenylphosphinyl)-3-phenylcycloheptanone (3R,4S)-5a as the major isomer. The diastereoselectivity of the initial tandem reactions was estimated to be 94:6 from the 31P NMR of a mixture of the diastereomeric ketal derivatives 6a and 6′a which were obtained by the reaction of 5a with (2R,3R)-2,3-butanediol, and the absolute configuration of the major isomer was determined by the single-crystal X-ray analysis. Similar reactions using some 8-phenylmenthyl alkenoates were attempted. As a result, it was clarified that the corresponding trans-ketones 5b-d were obtained and that the diastereomer ratios of their ketal derivatives were 60:40-73:27.
