Fischer-type alkyl(hydrazino)carbene complexes: new synthetic potential incomparison with aminocarbene complexes

A general picture is given of the reactivity of the two Fischer-type alkyl( hydrazino)carbene complexes (CO)(5)Cr=C(CH3)N(Bn)N(CH3)(2) (1) and (CO)(4)C r=C(CH3)N(Bn)N(CH3)(2) (3). Unlike their organic isolobal hydrazide analogu es, they easily yield the corresponding alpha -anions at -78 degreesC, whic h react with various electrophiles. Furthermore, the tetracarbonyl chelate 3 (easily generated from 1) has greater synthetic potential than aminocarbe nes: for example, it can be alkylated stepwise twice in the alpha -position , thus making it possible to introduce a new stereogenic centre in the mole cule. (C) 2001 Elsevier Science B.V. All rights reserved.