Enantioselective ester hydrolyses using Rhizopusnigricans: stereoselective synthesis and absolute stereochemistry of (−)-cis- and (−)-trans-1-hydroxy-4-methyl-1,2,3,4-tetrahydronaphthalene

Abstract

Enantioselective hydrolysis of racemic acetates of cis-and trans-l-hydroxy-4-methyl-l,2,3,4-tetrahydronaphthalene using Rhizopus nigricans yields chiral alcohols. The absolute stereochemistry of these compounds, and that of a key intermediate in their stereoselective synthesis, r-l-hydroxy-2,t-bromo-4,c-methyl-1,2,3,4-tetrahydronaphthalene, were determined by chemical transformations to I -oxo-4-methyl-l,2,3,4-tetrahydronaphthalene of known absolute stereochemistry. The relative stereochemistry of the acetate of the key intermediate was established by X-ray crystallography.MASAJI KASAI, HERMAN ZIFFER et J. V. SILVERTON. Can. J. Chem. 63, 1287 (1985.L'hydrolyse knantiosklective des acCtates racCmiques des hydroxy-.I mCthyl-4 tetrahydro-1,2,3,4 naphtalenes-cis et trans, effectuke en prksence de Rhizopus nigricans, conduit a des alcools chiraux. On a dktermink la stkrkochimie absolue de ces composCs ainsi que celle d'un intermkdiaire clk dans leur synthiise stCrkosklective, le hydroxy-I-r bromo-2,t mCthyl-4,c tetrahydro-1,2,3,4 naphtalkne, en leur faisant subir des transformations chimiques conduisant a 1'0x0-l mCthyl-4 tktrahydro-1,2,3,4 naphtalene de stCr6ochimie absolue connue. On a dCtermint la stkrkochimie relative de l'acktate de I'intermkdiaire clC en faisant appel i la diffraction des rayons-X.[Traduit par le journal]We recently reported (1) on a method for preparing chiral alcohols of a predictable absolute stereochemistry using the mold, Rhizopus nigricans, by enantioselective hydrolysis of the corresponding racemic acetates. The absolute stereochemistry of the alcohols formed was accounted for by a suggested rule ( l a ) which states that the enantiomer shown in Fig. 1 is the one more rapidly hydrolyzed. The relative sizes of R, and R2 required to account for our results in these hydrolyses are identical to those employed in Horeau's method (2). For example, an aromatic group (R,) is always larger than an alkyl group (R2) and, in cyclic carbinols, a substituted methylene group is larger than an unsubstituted one, etc. This simple concept and the associated empirical observations (1) account for the configurations of some fifty acyclic and cyclic carbinols, several of which required special explanations in order to reconcile their known absolute stereochemistry with data from Horeau's method. Since knowledge of the relative sizes of substituents is critical in predicting the absolute stereochemistry of carbinols formed in these hydrolyses, we needed to establish the influence of distant groups on the relative sizes of substituents on the carbinol carbon. Many data (1 c ) have been collected on 2-substituted 1-acetoxy-l,2,3,4-tetrahydronaphthalenes, and it has been established that a fused benzene ring is effectively larger than a saturated carbon bearing two hydrogens, but smaller than one in which one or both of the hydrogens has been replaced by a chlorine or bromine atom or a methyl or hydroxyl group. In order to examine the influence of distant groups, we have therefore investigated the effects associ...

Enantioselective Route to Threo 8.0.4'-Type Neolignans: Synthesis of (-)-Virolin

“…It is known (5)(6)(7)(8)(9)(10) that the mold, Rbizopus nigricans, partially hydrolyzes racemic acetates to alcohols enriched in one enantiomer of predictable configuration, while the recovered acetate is enriched in the antipode. Unfortunately, under a great number of experimental conditions, synthetic (±)-virolin acetate (2) was immune to the action of the mold.…”

“…The absolute configuration of the carbinolic carbon in ( + )-5 was determined as IS [absolute stereochemistry of the threo bromohydrin (75,85)}, by using the rule proposed by Ziffer (6)(7)(8) and the assumption that, in acyclic systems, disubstituted carbons are effectively smaller than an aromatic ring (19). Thus, the enantiomer shown in Figure 1 would be the more rapidly hydrolyzed.…”

Oxidative β-Halogenation of Alcohols: A Concise and Diastereoselective Approach to Halohydrins

“…1 H NMR (400 MHz, CDCl 3 ) δ 7.57 -7.53 (m, 1H), 7.42 (dd, J = 8.1, 1.9 Hz, 1H), 7.10 (d, J = 8.0 Hz, 1H), 5.28 (d, J = 5.8 Hz, 1H), 4.26 (td, J = 7.4, 6.0 Hz, 1H), 3.52 (dd, J = 16.2, 7.2 Hz, 1H), 3.15 (dd, J = 16.3, 7.6 Hz, 1H), 2.47 (d, J = 4.8 Hz, 1H). 13 6 The reaction of 7 The reaction of 4-methyl-1,2,3,4-tetrahydronaphthalen-1-ol 3u (81.1 mg, 0.5 mmol), NaBr (102.…”

“…13 C NMR (100 MHz, CDCl 3 ) δ 141.6, 139.7, 129.0, 127.6, 124.6, 124.1, 83.4, 54.5, 40.4. 3 The reaction of 6,7,8,9-tetrahydro-5H-benzo [7]annulen-5-ol 3r (89.1 mg, 0.5 mmol), NaBr (102.…”