Cyclohexanones keto aldehydes from

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. 

Cyclo hexenes with substituents in the 1-position (2), made from cyclohexanone and Grignard reagents, cleave to give keto acids (3) or keto aldehydes according to conditions. 

The retro synthetic pathway is outlined in Scheme 49 and starts with the simplification of the TAN1251A again to the known intermediate 119, whose first conversion into the alkaloid had been reported by the same authors [63], The target compound 119, in turn, can be prepared from 126 also following their known protocol. Compound 126 should be obtained from 156 via installation of an azide group and A-alkylation. Disassembly of the cyclohexanone ring from 156 in a retrosynthetic sense leads to keto aldehyde 155, which may be prepared by alkylation of proline 154 followed by some functional group interconversion steps. 

An unusual reaction was been observed in the reaction of old yellow enzyme with a,(3-unsat-urated ketones. A dismutation took place under aerobic or anaerobic conditions, with the formation from cyclohex-l-keto-2-ene of the corresponding phenol and cyclohexanone, and an analogous reaction from representative cyclodec-3-keto-4-enes—putatively by hydride-ion transfer (Vaz et al. 1995). Reduction of the double bond in a,p-unsaturated ketones has been observed, and the enone reductases from Saccharomyces cerevisiae have been purified and characterized. They are able to carry out reduction of the C=C bonds in aliphatic aldehydes and ketones, and ring double bonds in cyclohexenones (Wanner and Tressel 1998). Reductions of steroid l,4-diene-3-ones can be mediated by the related old yellow enzyme and pentaerythritol tetranitrate reductase, for example, androsta-A -3,17-dione to androsta-A -3,17-dione (Vaz etal. 1995) and prednisone to pregna-A -17a, 20-diol-3,ll,20-trione (Barna et al. 2001) respectively. 

Acetone is readily converted to isopropylamines in the vapor phase under conditions that apply for the lower (Cj-C ) aldehydes. The preparation of 2-aminobutane from methylethyl ketone (butanone-2) is satisfactorily carried out in the liquid phase, preferably in the presence of butanol-2 since the latter can also be converted to amine by ammonolysis. The intranuclear ketone cyclohexanone can be converted to cyclohexylamine by hydroammonolysis in the vapor phase. The preparation of 12-amino-stearamide from the corresponding keto acid is, however, best carried out in the liquid phase. The pertinent reactions are ... 

The flavoenzyme from Yersinia pseudotuberculosis (YerD) catalyzes in vivo the acyloin condensation of pyruvate to the ketone, cytidine-5 -diphosphate-3,6-di(deoxy)-4-keto-D-glucose [52]. Investigations on its synthetic capabilities revealed that this enzyme can catalyze aldehyde-ketone cross-acyloin condensations, furnishing tertiary alcohols (Table 10.6) [52], Small cyclic aliphatic ketone derivatives, for example, cydohexanone and methylated cyclohexanones, tetrahydro-2H-pyran-3-one (Table 10.6), open-chain ketones containing an ether moiety, diketones, and ketones containing an - or p-ketoesters were aU successfully converted [52],... 

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