| 15049656 |
Brana P, Gimeno J, Sordo JA: Unusual intramolecular [2 + 2] cycloaddition of allyl and vinylidene C=C bonds under mild conditions: a theoretical analysis. J Org Chem. 2004 Apr 2;69(7):2544-50.
A theoretical analysis allows for the rationalization of the recently reported unusual formation under mild conditions of a cyclobutylidene ring from a diastereoselective [2 + 2] intramolecular cycloaddition of two C=C systems. The reaction takes place by heating in dichloromethane the vinylidene complexes [Ru ((eta (5),eta (3)-C (9) H (7))[=C=C (R) H][kappa (1)-(P)-PPh (2)(C (3) H (5))](PPh ( 3))][BF (4)] (R = Ph, p-Me-C (6) H (4)) (1) yielding the bicyclic alkylidene complexes [Ru ((eta (5),eta (3)-C (9) H (7))[kappa (2)-(P,C)-(=CC (R) HCH (2) CHCH (2)-PPh (2)](P Ph (3))][BF (4)] (2). The proposed mechanism represents an alternative to the classical Woodward-Hoffmann's supra-antara approach. |
31(0,1,1,1) |