A Novel Tandem Cyclization of 2,7- or 2,8-Bis-Unsaturated Esters Mediated by (η2-Propene)TiX2 (X = Cl or O-i-Pr). A Facile Construction of Bicyclo[3.3.0]octane, -[4.3.0]nonane, and -[3.1.0]hexane Skeletons
Intramolecular Cyclization of 2,7- or 2,8-Bis-unsaturated Esters Mediated by (η<sup>2</sup>-Propene)Ti(O-<i>i</i>-Pr)<sub>2</sub>. Facile Construction of Mono- and Bicyclic Skeletons with Stereoselective Introduction of a Side Chain. A Synthesis of <i>d</i>-Sabinene
作者:Hirokazu Urabe、Ken Suzuki、Fumie Sato
DOI:10.1021/ja9716160
日期:1997.10.1
tert-Butyl 2-en-7-ynoate 6 was treated with (η2-propene)Ti(O-i-Pr)2 (3), generated in situ from Ti(O-i-Pr)4 or Ti(O-i-Pr)3Cl and i-PrMgCl, in ether at −50 to −20 °C to afford the product 8 in good yield. The presence of the intermediate titanabicycle 7 was verified by bis-deuterolysis with excess D2O. When the titanabicycle 7 was treated with 1.1 equiv of i-PrOD and then worked up as usual, the monodeuterated
A Novel Tandem Cyclization of 2,7- or 2,8-Bis-Unsaturated Esters Mediated by (η<sup>2</sup>-Propene)TiX<sub>2</sub> (X = Cl or O-<i>i</i>-Pr). A Facile Construction of Bicyclo[3.3.0]octane, -[4.3.0]nonane, and -[3.1.0]hexane Skeletons