2-Allyl-2-methyl cyclohexanone

CYCLOHEXANONE, 2-ALLYL-3-METHYL-(CYCLOHEXANONE, 3-METHYL-2-(2-PROPENYL)-], 52 Cyclohexanone, 2-allyl-5-methyl- Cyclohexanone, 5-methyl- 2-(2-propenyl)-], 55... 

Cyclohexanone, 2-allyl-5-methyl-, 56, 55 Cyclohexanone, 3-(3-butenyl)-2-methyl-, 56,56... 

Using the 3 mm. by 2 m. gas chromatography column described above, a mixture of stereoisomers of 2-allyl-5-methylcyclohexanone [Cyclohexanone, 5-methyl-2-(2-propenyl)-], prepared by allylation of the enamine of 3-methylcyclohexanone,7a showed peaks at retention times of 8.4 minutes (more stable isomer) and 9.6 minutes. A mixture of the two isomeric 2-allyl-3-methylcyclohexanones and the two isomeric 2-allyl-5-methylcyclohexanones clearly exhibited four distinct peaks on gas chromatography. 

Elemental antimony is known to mediate the Barbier-type allylation of aldehydes by allylic halides.35 The active intermediates are believed to be allylic antimony(m) species, which are generated from the antimony(O) and the halides. In fact, allylic dichlorostibanes, produced by metathesis of SbCl3 with the corresponding allylic stannanes, react with benzaldehyde to give homoallyl alcohols, where the C-C bond is constructed with -selectivity (Equation (l)).36 Fluoride salts such as KF, NaF, RbF, and CsF accelerate the Sb-mediated Barbier-type allylation with allyl bromide in aqueous media (Equation (2)).37 In the absence of the fluoride ion, no allylation occurs. Although aromatic and aliphatic aldehydes are allylated in good yields by a combined use of Sb-KF, acetophenone, cyclohexanone, and methyl pyruvate remain untouched. 

The checkers obtained an additional 2-5 g. of 2-allyl-3-methyl-cyclohexanone by redistilling the column wash and the pot residue through a short-path distillation column. This raised the total yield to 14.9-18.1 g. (54-66%). 

Cyclohexanones, 2-alkyl-5 methyl-, 56 Cyclohexene, 34 Cyclohexene, 1,6-dibromo-, 34 CYCLOHEXENE, 3-METHYL-, 101 Cyclohexene, 1-phenyl- [Benzene, (1-eyclohexen-l-yl)-], 106 2-Cyclohexen-l-ol, 2-bromo-, 34 2-Cyclohexen-l-ol, 3-methyl-, 101 2-Cyclohexen-l-one, 2-allyl-3-methyl-[2-Cyclohexen-l-one, 3-methyl-2-(2-piopenyl)-], 55... 

Organoaluminum-promoted Beckmann rearrangement/methylation of cyclohexanone oxime mesylate, followed by allylation of ketimine 40a and Mannich cyclization of the intermediate iminium-allylsilane, provides piperidine 40b possessing cxo-unsaturation (08BKC1669). 

In 1999 Trost and Schroder reported on the first asymmetric allylic alkylation of nonstabilized ketone enolates of 2-substituted cyclohexanone derivatives, e.g. 2-methyl-1-tetralone (45), by using a catalytic amount of a chiral palladium complex formed from TT-allylpaUadium chloride dimer and the chiral cyclohexyldiamine derivative 47 (equation 14). The addition of tin chloride helped to soften the lithium enolate by transmetala-tion and a slight increase in enantioselectivity and yield for the alkylated product 46 was observed. Besides allyl acetate also linearly substituted or 1,3-dialkyl substituted allylic carbonates functioned well as electrophiles. A variety of cyclohexanones or cyclopen-tanones could be employed as nucleophiles with comparable results . Hon, Dai and coworkers reported comparable results for 45, using ferrocene-modified chiral ligands similar to 47. Their results were comparable to those obtained by Trost. 

Capon and Wu have shown that the rate of hydrolysis of secondary enamines of cyclohexanone (13 and 14) is decreased only slightly by the 2) methyl group. They have therefore concluded that the methyl substituent has little effect on the ground state or the transition state conformations of secondary enamines . However, in this case there is no developing allylic strain whether the transition state is reactant-like or product-like (see also Section VIII) and pn-conjugation is uninhibited. The pn-conjuga-tion in secondary, -disubstituted acyclic enamines (15) compared to the corresponding tertiary enamines (16) is also demonstrated by the UV and NMR evidence provided by Capon and Wu . 

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