Cyclohexanone dimethylhydrazone

In the case of titanated cyclohexanone dimethylhydrazone 3 the. wt-adduct is obtained nearly... 

The effect of varying R1/R2, the ligands at titanium and the substituents at the terminal nitrogen atom should allow for more insight. In this connection it is interesting to note that the titanated form of cyclohexanone dimethylhydrazone reacts with benzaldehyde >98% erythro-selectively115). 

Figure 3 Molecular structure of the asymmetric unit of lithiated cyclohexanone dimethylhydrazone polymer (hydrogen positions have been left off for clarity) ...

The solid state structures (as well as those in solution) have been determined for the dimeric species (i) lithiated 2-Me02 Cyclohexanone dimethylhydrazone... 

The vinylbenzothiazoles can also function as very efficient Michael acceptors (78TL13). The a-lithio derivative of acetone dimethylhydrazone undergoes clean conjugate addition to the vinylbenzothiazole derived from cyclohexanone to provide, upon quenching the a-lithiobenzothiazole anion with methyl iodide and hydrolyzing the dimethylhydrazone group, the ketone (579) (93% overall, 86 14 cis trans). The pure cis keto benzothiazole was converted to the cis keto aldehyde (580), and then cyclized with p-toluenesulfonic acid to the A -3-octalone (581 Scheme 127). Many other examples of the use of this chemistry for the construction of fused and spiro ring systems have been developed. 

The azaallyl oidates, Le. enolates derived from ketone imines or hydrazones are synthetic equivalents of the ketone endates and thus two examples of azaallyl enolates are included in th section. Lithiated cyclrdiexanonephenylimine (151) crystallizes out of hydrocarbon solution as the dimeric diisopropylamine solvate (152). Significant disorder between the cyclohexyl and the phoiyl moieties is obse ed in this crystal structure however, it is clear that there are no V-az yl carbm contacts in this structure. This lithiated imine structure can be compared with the lithittted dimethylhydrazone of cyclohexanone... 

The anion of cyclohexanone AT,A dimethylhydrazone shows a strong preference for axial alkylation. 2-Methylcyclohexanone A, iV-dimethylhydrazone is alkylated by methyl iodide to give cw-2,6-dimethylcyclohexanone. The methyl group in the hydrazone occupies a pseudoaxial orientation. Alkylation apparently is preferred anti to the lithium cation, which is on the face opposite the 2-methyl substituent. 

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