Organic syntheses-via transition-metal complexes. 110. A convenient regio-and stereoselective approach to the angular allylation of bicyclic cyclopentadienes generated by the (1-alkynyl)carbene complex route

Reaction of the [2-(1-cyclopentenyl)ethynyl] carbene tungsten compound la w ith secondary allylamines RNH-CH2CH=CH2 (R = CH2CH=CH2, CH2CH2CH3, PhCH2) ( 2a-c) and pyridine affords (C6a-allyltetrahydropentalen-1-ylidene)amines 3a -c in 72-77% yields. Compounds 3 result from a highly regio- and stereosele ctive N,C-allyl rearrangement of 1-(allylamino)cyclopentadiene precursors 7 , which are generated in a kinetically controlled process from compound la. The reaction has been successfully extended to the formation of (C7a-allyl pentahydro-3aH-inden-1-ylidene 8a-c from [2-(1-cyclohexenyl)ethynyl]carbene tungsten complex Ib and (C8a-allylhexahydro-3aH-azulenylidene)amines 12a,b from [2-(1-cycloheptenyl)ethynyl] carbene tungsten complex 1c.