The methyl esters of 3R,7S-dimethyl- and 3R,5R,7S-trimethyl-8-hydroxyoctanoic acids have been prepared in good yields and with e.e. >98% by chemical elaboration of the known exo,exo-3,7-dimethylbicyclo[3.3.1]nonan-9-one, the key step involving the desymmetrisation of the intermediate meso-ketones cis-3,7-dimethyl- and cis,cis-3,5,7-trimethyl-cyclooctanone through the corresponding chiral enolates generated by the lithium amide of the (+)bis[(R)-(1-phenylethylamine)]. The very high enantioselectivity observed might be related to the conformational features of the eight-membered ring
Gambacorta, A., Tofani, D., Lupattelli, P., Tafi, A. (2002). Desymmetrisation of meso-methyleyclooctanones. Highly enantioselective synthesis of C-8 syn-isoprenoid and syn,syn-deoxypropionate subunits from a bicyclo[3.3.1]nonane precursor. TETRAHEDRON LETTERS, 43(12), 2195-2198 [10.1016/S0040-4039(02)00229-0].
Desymmetrisation of meso-methyleyclooctanones. Highly enantioselective synthesis of C-8 syn-isoprenoid and syn,syn-deoxypropionate subunits from a bicyclo[3.3.1]nonane precursor
GAMBACORTA, Augusto;TOFANI, DANIELA;
2002-01-01
Abstract
The methyl esters of 3R,7S-dimethyl- and 3R,5R,7S-trimethyl-8-hydroxyoctanoic acids have been prepared in good yields and with e.e. >98% by chemical elaboration of the known exo,exo-3,7-dimethylbicyclo[3.3.1]nonan-9-one, the key step involving the desymmetrisation of the intermediate meso-ketones cis-3,7-dimethyl- and cis,cis-3,5,7-trimethyl-cyclooctanone through the corresponding chiral enolates generated by the lithium amide of the (+)bis[(R)-(1-phenylethylamine)]. The very high enantioselectivity observed might be related to the conformational features of the eight-membered ringI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
