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The lithium salts of t-butyl-and trityl-hydrazones react with methyl crotonate to form C-trapped azo-esters and similar products were observed from a thermal ene-reaction of aldehyde t-butylhydrazones with methyl acrylate or acrylonitrile, and aldehyde phenylhydrazones with methyl acrylate; these products can be diverted into synthetically useful y-keto-esters, y-keto-nitriles, saturated esters, y-alkyl-2-pyrrolidonesr and y-amino-esters.Recently we described the use of t-butylhydrazones (la) as acyl anion equivalents,' and the use of trityl (lb) and diphenyl-4-pyridylmethyl (lc) hydrazones for reductive C-C bond formation from aldehydes and ketones2 Herein we report C-C bond forming reactions by the reaction of these hydrazones with Michael type electrophiles in both ionic (Scheme 1) and thermal (Schemes 2 and 3) type pathways.Thus treatment of the t-butylhydrazones (la) with n-butyllithium (0.95 equiv.) in tetrahydrofuran (THF) at 0 "C gave the azo-anion (2) which was cooled to -78 "C and treated with methyl crotonate (1.0 equiv., -78 "C, 30 min) (Scheme 1). Acetic acid (1.0 equiv.) was added, and in the case of ketone t-butylhydrazones, the stable azo-esters [(3a), 58%; (3b), 53%] were isolated by chromatography. ' r The azo-esters (3) derived from aldehyde t-butylhydrazones were not isolated, but directly isomerised [trifluoroacetic acid (TFA), 5 h, 20 "C] LI (1) a; R3=But (2) b; R3=CPh3 c ; R3 = CPh2(4-pyridyl) ii,iii R3 I R' N=N' R * ( M O M e Me 0 /ph3 (3) b; a; R',R2= R' = R2 = ;[iHzIs-,

Die Lithiumverbindungen (II) der Hydrazone (I) reagieren mit Methylcrotonat (III) zu den Azo‐estern (IV).

The conversion (IIId) ‐ (VIII) exemplifies the use of the title compounds (III) [prepared from (I)] as acyl‐anion equivalents: anions of type (IV) generated from aldehydes (IIId)‐(IIIg) are treated with an electrophile such as (V) to yield (VI); subsequent tautomerization [‐ (VII)] and hydrolysis provides the target compound (VIII).