Details

Autor(en) / Beteiligte

• Mikołajczyk, Marian
• Midura, Wanda H.
• Michedkina, Elena
• Filipczak, Agnieszka D.
• Wieczorek, Michał W.

Titel

Stereoselective Cyclopropanation of 2-[(S)-(4-Methylphenyl)sulfinyl]cyclopent-2-en-1-one with Sulfur Ylides and α-Halo Carbanions. Preliminary Communication

Ist Teil von

• Helvetica chimica acta, 2005-07, Vol.88 (7), p.1769-1775

Ort / Verlag

Zürich: WILEY-VCH Verlag

Erscheinungsjahr

2005

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• The cyclopropanation of the title compound (S)‐2 with various sulfur ylides has been examined. The reaction with methylenesulfonium ylides gave the corresponding cyclopropanes 4 with low diastereoselectivity. The formation of the second product 5 arising from the subsequent methylenation of the CO group was also observed. A clean cyclopropanation of (S)‐2 took place with ethyl (dimethylsulfanylidene)acetate affording the cyclopropanes 6, with high π‐facial selectivity, but low endo/exo ratio. A high endo/exo selectivity, but low π‐facial selectivity was observed in the reaction of (S)‐2 with (2‐ethoxy‐2‐oxoethyl)(diphenyl)sulfonium tetrafluoroborate. The use of α‐bromoacetate carbanion as the cyclopropanation reagent resulted in the formation of 6 with very high facial and endo/exo‐selectivity. In a proposed explanation of the stereochemical outcome of the cyclopropanations investigated, the ground‐state conformation of the sulfoxide 2 and the transition‐state structure of the initial addition step were taken into account.