Synthetic Entry into 1-Phosphono-3-azabicyclo[3.1.0]hexanes
摘要:
3-Azabicyclo[3.1.0]hex-2-en-1-yl phosphonates were prepared in a five-step reaction route from beta-ketophosphonates. The key steps in this sequence are an atom-transfer radical cyclization and an unforeseen lithium halogen exchange with n-BuLi. The cyclization reaction proceeds with excellent diastereoselectivity. The resulting cyclic imines were reduced, and 3-azabicyclo[3.1.0]hexan-1-yl phosphonates were obtained.
Formal Intramolecular (4 + 1)-Cycloaddition of Dialkoxycarbenes: Control of the Stereoselectivity and a Mechanistic Portrait
作者:Francis Beaumier、Marianne Dupuis、Claude Spino、Claude Y. Legault
DOI:10.1021/ja211927b
日期:2012.4.4
The stereoselective synthesis of 5-5, 6-5, and 7-5 fused O-heterocyclic compounds is reported. The key reaction is a formal intramolecular (4 + 1)-cycloaddition involving a dialkox-ycarbene and an electron-deficient diene where the stereo-selectivity is dependent on the length of the tether. An analysis of the stereochemical outcome of this reaction sheds light on its complex mechanistic picture. High-level calculations were used to support the proposed mechanistic portrait.
Huff, Ann M.; Beam, Charles F., Journal of Heterocyclic Chemistry, 1986, vol. 23, p. 1343 - 1346