3- Hydroxy-2-methylcyclohexanone

Hydroxy-2-methylcyclohexanone, 214 a-Hydroxymethyl ketones, 264-266 p-Hydroxymethylphenylboronic acid, 194 N-Hydroxy-5-norbornene-endo-2,3-... 

A) (23), was obtained in an improved yield using the modified literature procedure (28) starting from benzene diazonium chloride (1054) and hydroxymethylene-5-methylcyclohexanone (1055). A biomimetic coupling of l-hydroxy-3-methylcarba-zole (O-demethylmurrayafoline A) (23) by reaction with di-ferf-butyl peroxide l(t-BuO)2] afforded the dimer of O-demethylmurrayafoline A (204). Finally, oxidation of 204 with PCC afforded (+ )-bismurrayaquinone-A (215). The resolution of atropo-enantiomers was achieved by chiral HPLC using Chiracel OF. The assignment of the absolute configuration of the two enantiomers (S)-215 and (f )-215 was achieved by comparison of their theoretical and experimental circular dichroism (CD) spectra (166,167,661) (Scheme 5.164). 

Formation of CK-configurated cyclobutanones has also been observed with 2-methylcyclopen-tanone and 2-methylcyclohexanone/8 However, stereoreversed eyclobutanone formation can be achieved by opening the intermediate oxaspiropentane with sodium phenyl selenide, oxidation of the resulting / -hydroxy selenide with 3-chloroperoxybenzoic acid and subsequent rearrangement in the presence of pyridine/18 Thus, from one oxaspiropentane 8, either stereoisomeric eyclobutanone cis- or lrans-9 was produced. The stereoreversed eyclobutanone formation proceeds from a stereohomogenous / -hydroxy selenoxide and is thought to be conformationally controlled. 

Other reducing agents, which lead to unsaturated glycols of type 182, include thiourea,182 aluminum amalgam,214 and lithium aluminum hydride.192,218 The reaction of dihydroascaridole (181) with ferrous sulfate or titanous chloride yields propane and 4-hydroxy-4-methylcyclohexanone while ascaridol gives 3,6-endoxo-4-isopropyl-6-methylcyclohexane-1,2-diol and 4-hydroxy-3-isopropylcyclohexa-... 

The oxidation, vhich is quite different from that promoted by RUO4, is highly useful. Indeed, the oxidation of 1-methylcyclohexene 44 under the conditions gives 2-hydroxy-2-methylcyclohexanone (45) (67%), while oxidation of the same substrate 44 under the conditions in which RUO4 is generated catalytically gives 6-oxohepta-noic acid (46) (91%) (Eq. 3.67). 

Hydroxy-a-phenylthio-acids and their methyl esters can be prepared by condensations between carbonyls and the bis-anionic species (13) from phenyl-thioacetic acid or the monoanion (14) from methyl phenylthioacetate respectively. Yields are often excellent although the bis-anion (13) is less reactive, failing to condense with 2-methylcyclohexanone or acetophenone. With enones, (13) undergoes [1,2] addition by contrast the monanion (14) adds in a Michael fashion. 

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