2,6-Dimethylcyclohexanone

Dimethylcyclohexanone and 2-benzyl-2-methylcyclohex-anone have been prepared similarly in yields of 60% and 55%, respectively.2 The procedure has been extended to the synthesis of 9-methyl-, 9-w-butyl-, and 9-benzyl-l-decalone from the dianion of 2-formyl-l-decalone in yields of 55%, 48%, and 58%, respectively.2... 

Elution with hexane-ethyl acetate (10 1-5 1) gives 5-6 g of recovered starting material. Further elution with hexane-ethyl acetate (5 1-1 Z) gives 7.7-7.9 g (47-52X) of (S)-3-hydroxy-2,2-dimethylcyclohexanone. An analytical sample can be obtained by distillation, bp 85-87°C/3.7 mm, [a] +23.0° (CHC13, o 2.0) (Notes 13, 14, and 15). 

Microbial reduction of prochiral cyclopentane- and cyclohexane-1,3-diones was extensively studied during the 1960 s in connection with steroid total synthesis. Kieslich, Djerassi, and their coworkers reported the reduction of 2,2-dimethylcyclohexane-l,3-dione with Kloeokera magna ATCC 20109, and obtained (S)-3-hydroxy-2,2-dimethylcyclohexanone. We found that the reduction of the 1,3-diketone can also be effected with conventional baker s yeast, and secured the hydroxy ketone of 98-99% ee as determined by an HPLC analysis of the corresponding (S)-a-methoxy-a-trifluoromethylphenylacetate (MTPA ester).(S)-3-Hydroxy-2,2-dimethy1cyc1ohexanone has been proved to be a versatile chiral non-racemic building block in terpene synthesis as shown in Figure 1. 

HYDROXY-1-CYCLOHEXENE-1-CARBOXALDEHYDE 1-CYCLOHEXENE-1 -CARBOXALDEHYDE, 3-HYDROXY- (67252-14-6), 67, 205 (S)-(+)-3-HYDROXY-2,2-DIMETHYLCYCLOHEXANONE Cyclohexanone, 3-hydroxy-2,2-dimethyl-, (S)- (87655-21-8), 68, 56 Hydroxylamine, N-phenyl-, 67, 187 a-Hydroxylation of ketones, 66, 138... 

S)-3-Hydroxy-2,2-dimethylcyclohexanone as a Building Block. Reduction of 2,2-dimethylcyclohexane-l,3-dione (24) with baker s yeast gives (S)-3-hydroxy-2,2-dimethylcyclohexanone (25) of 98-99% e.e. 21). This hydroxy ketone 25 was proved to be a versatile chiral building block in terpene synthesis (3). 

Other, less activated, sp C-H bonds in addition to the benzylic C-H of 8-alkylquinolines will undergo cyclometalation. (ii)-2,2-Dimethylcyclohexanone oxime will react with Na2PdCLi to give metalation of the unactivated CH3 group in 85% isolated yield (equation 70). 

For example, 2-methylcyclohexanone can be converted to either 2,6-dimethylcyclohexanone (A) or 2,2-dimethylcyclohexanone (B) by proper choice of reaction conditions. 

Yamamoto and Saito reported that the kinetically controlled generation of the more substituted enolate of unsyimnetrical dialkyl ketones can be realized by the combined use of ATPH and LDA [175]. Precomplexation of ATPH with 2-methyl-cyclohexanone (175) at -78 °C in toluene was followed by treatment with LDA in THF, and the mixture was stirred for 1 h. Subsequent treatment with methyl trifluoro-methanesulfonate (MeOTf) furnished 2,2-dimethylcyclohexanone (177) and 2,6-dimethylcyclohexanone (176) in the ratio 32 1 (53 % isolated yield). Use of ter/-butyl-dimethylsilyl triflate (TBSOTf) in place of alkyl triflates in this alkylation system produced siloxybutylated product 178 as a result of THF ring-opening alkylation occurred similarly at the more hindered a-carbon of the unsymmetrical ketone 175 (Sch. 136) [176]. 

Yeast Reduction of 2,2-Dimethylcyclohexane-l,3-dione (S)-(+)-3-Hydroxy-2,2-dimethylcyclohexanone... 

An approach to the polycyclic diterpenes, including veatchine, was initiated by Meyer. 2,2-Dimethylcyclohexanone was converted to the cyano-enone (110). This was elaborated into the cyano-phenol (111) which has potential for the synthesis of the alkaloids. 

The O18 exchanges accompanying the pinacol rearrangement in the cyclohexane-1,2-diol and cyclopentane-l,2-diol systems have also been investigated. The pinacolic rearrangement of both cis- (17) and trans-1,2-dimethylcyclohexane-l,2-diol (18) in aqueous acid gives 1-acetyl-methylcyclopentane and a small amount of 2,2-dimethylcyclohexanone... 

YUST REDUCTION OF 2,2-DIMETHYLCYCLOHEXANE-l,3-OIONE (S)-(+)-3-HYDROXY-2,2-DIMETHYLCYCLOHEXANONE (Cyclohexanone, 3-hydroxy-2,2-dimethyl-, (S)-)... 

---