STEREOCHEMICAL CONTROL OF N,N-DISUBSTITUTION IN ALKYNYLAMINOCARBENE COMPLEXES OF CHROMIUM(0) AND TUNGSTEN(0)

Stereocontrol in the introduction of substituents on the nitrogen of a lkynylaminocarbene complexes can be achieved by a proper sequential am inolysis of the starting alkoxy carbene analogs followed by treatment of the resulting (E-alkylamino)carbene complex with Cs2CO3 in the pres ence of the desired electrophile. The use of Cs2CO3 as a base affords good yields of N,N-disubstituted alkynylcarbene complexes. The isomeri zation described for other systems was avoided in this case. The react ion is also applicable to bulky electrophiles like (-)-myrtenyl or (-) -perillyl bromides and also to arylcarbene complexes.