ORGANIC SYNTHESES VIA TRANSITION-METAL COMPLEXES .70. -[2-(GALACTOPYRANOSYLAMINO)ETHENYL]CARBENE AND 3-(GALACTOPYRANOSYLAMINO)-1,2-PROPADIENYLIDENE COMPLEXES ON 3-ADDITION OF 2,3,4,6-TETRA-O-PIVALOYL-BETA-D-GALACTOPYRANOSYLAMINE TO ALKYNYLCARBENE COMPLEXES (M=CR, W) - ATROPISOMERIC GALACTOPYRANOSYL PYRROLES BY REACTION OF [2-(GALACTOPYRANOSYL-AMINO)ETHENYL]CARBENE COMPLEXES WITH ISOCYANIDES

Enantiomeric pure (2-aminoethenyl)carbene complexes L(n)M=C(OEt)-CH=C(Ph)NHR* (Z)-3 and 3-amino-1,2-propadienylidene complexes L(n)M=C=C=C(Ph)NHR* 4 [R*=2,3,4,6-tetra-O-pivaloyl-beta-D-galactopyranosyl] are obtained by the addition of galactopyranosylamine R*-NH2 2 to the corresponding alkynylcarbene complexes L(n)M=C(OEt)-C=CPh 1 [L(n)M=(CO)5Cr, (CO)5W]. Treatment of (Z)-3 with two equivalents of tert-butyl isocyanide (5) affords isocyanide complexes 6 and ketene imines 7. The latter cyclize spontaneously to give galactopyranosylpyrroles 8 which form stable atropisomers 8A and 8B.