Asymmetrization of all-cis-3,5-dihydroxy-1-(methoxycarbonyl)cyclohexane and of the 4-methyl and 4-ethyl substituted homologues

A Practical Synthesis of 14-epi-19-nor-1α,25-Dihydroxyvitamin D3 Analogues and Their A-ring Epimers

“…The current synthesis is centered around methyl all-cis-3,5-dihydroxy-cyclohexanecarboxylate (25) [19,20] as the starting material (Scheme 2). In contrast to (Ϫ)-quinic acid (22), this possesses only the three essential functions, thus minimizing the number of functional group transformations necessary.…”

“…Scheme We have already described the asymmetrization of 25 by a PPL-catalyzed transesterification (PPL: porcine pancreas lipase) with vinyl acetate, which afforded crystalline, enantiopure 26 in high yield (Scheme 2). [20] The excellent result of this key step provided an efficient route to 14a. The tosylation of 26, followed by acetate methanolysis, gave the alcohol 27.…”

Chemo-enzymatic pathways toward pinene-based renewable materials

“…The SobMA was synthesized via a conventional chemical approach starting from commercially available sobrerol, using methacryloyl chloride and triethyl amine in DMF. DMF was not a preferred solvent but despite previous reports, 48,49 sobrerol proved difficult to dissolve. Purification via medium pressure liquid chromatography (MPLC) yielded the liquid SobMA monomer in 66% yield.…”

Enantioselective Enzymatic Desymmetrizations in Organic Synthesis

“…Likewise, within the context of a program directed toward the enantioselective total synthesis of natural products and analogues thereof containing a cyclohexane ring, the desymmetrization of meso all- cis- 3,5-dihydroxy-1-(methoxycarbonyl)cyclohexane and the 4-methyl and ethyl substituted analogues ( 61a − c ) was investigated (Scheme ) . The results obtained showed that preparative useful enantioselectivities were found for the PPL- and SAM II-catalyzed transesterifications of 61a and 61b − c , respectively, in which the two enzymes showed opposite enantiopreferences.…”