The reaction of tert-butylalkynyl chromium Fischercarbenecomplex 1 with nitrones 2 affords β-enamino-ketoaldehydes 4 by the light-promoted rearrangement of the corresponding [3+2] cycloadduct carbenecomplexes3. On the other hand, [3+2] cycloaddition of chiral nonracemic Fischeralkenylcarbenecomplexes 19 with nitrilimines 10 yields enantiomerically pure Δ2-pyrazolines with high regio- and diastereoselectivity