Diastereoselective synthesis of three-, five-, six-, and seven-membered rings from Fischer carbene complexes and 4-unsubstituted 1-amino-1,3-dienes

Fischer carbene complexes react with 4-unsubstituted 1-amino-1,3-dienes to give different carbocyclization products depending on the nature of the carbene complex and on the substitution pattern of the aminodiene. Thus, the reaction of arylcarbene chromium complexes and 1-aminodienes diastereoselectively affords cyclopropane derivatives by means of a formal [2+1] carbocyclization reaction. In particular, pentacarbonyl[(2-furyl)(methoxy)methylenelchromium complex furnishes formal [4+1] carbocyclization products. Starting from P-substituted alkenylcarbene complexes, formal [4+1] reactions occur and cyclopentenamine derivatives are diastereoselectively formed. However, when the alpha,beta-disubstituted alkenylcarbene complex pentacarbonyl[(5,6-dihydro-2H-pyran-2-yl)(methoxy)methylene] tungsten is used, the outcome of the reaction depends on the substitution on the carbon atom at the 3-position of the aminodiene, generating the [3+2] or [4+3]-cyclization products if the substituent is or is not a hydrogen atom, respectively. Finally, when the reaction is performed with alkynylcarbene complexes, benzaldehyde derivatives are obtained if the triple-bond substituent is a phenyl group or indene derivatives if the group is an alkenyl moiety.