beta-aminosubstituted alpha,beta-unsaturated Fischer carbene complexes as chemical multitalents

beta-Aminosubstituted alpha,beta-unsaturated Fischer carbene complexes of types 6/7/8 and 21 are readily available in two steps or even a single-pot operation hom hexacarbonylchromium and the appropriate alkyne 4 via the alkynyl-substituted complexes 5 by Michael type addition of a secondary (primary) amine or ammonia. With the right choice of substituents and reaction conditions, they can selectively react to give 2H-pyrroles 20 (ref. 17), 5-dialkylamino-3-alkoxycyclopenta-1,3-dienes 42 (which are synthetic equivalents of cyclopentenones and even cyclopentadienones) (refs. 29,31), pyridines 25 (ref. 19), 5-(1'-dialkylaminoalkenylidene)-4-ethoxycyclopent-2-enones 32 (ref. 25), 2-(1'-dialkylamino-1'-alkenyl)cyclopent-2-enones 38 (ref. 27), 2-acyl-3-dialkylaminocyclopent-2-enones 33 (ref. 26) and cyclopenta[b]pyrans 26 (refs. 20,23).