Biocatalytic oxidative kinetic resolution of sec-alcohols: stereocontrol through substrate-modification
摘要:
Whole lyophilised cells of Rhodococcus ruber DSM 44541 were employed for the oxidative kinetic resolution of sec-alcohols using acetone as hydrogen acceptor. The enantioselectivity of this process could be controlled effectively by introducing C-C multiple bonds into substrates, which were inefficiently recognised, in particular short-chain (omega-1)-alcohols and (omega-2)-analogs. Thus, the enantioselectivities of rac-2-pentanol (E= 16.8) and rac-3-octanol (E= 13.3) were significantly improved by introducing a C=C bond adjacent to the alcohol moiety to give racemic (E)-pent-3-en-2-ol and 4-(E)-octen-3-ol, which were resolved with excellent selectivities (E >100 and 50, respectively). In addition, it was found that high stereodifferentiation between the E- and Z-configured double bonds occurred, as the corresponding (Z)-isomers were not converted. Similar selectivity-enhancing effects were observed with acetylenic analogs. (C) 2003 Elsevier Science Ltd. All rights reserved.
Whole lyophilised cells of Rhodococcus ruber DSM 44541 were employed for the oxidative kinetic resolution of sec-alcohols using acetone as hydrogen acceptor. The enantioselectivity of this process could be controlled effectively by introducing C-C multiple bonds into substrates, which were inefficiently recognised, in particular short-chain (omega-1)-alcohols and (omega-2)-analogs. Thus, the enantioselectivities of rac-2-pentanol (E= 16.8) and rac-3-octanol (E= 13.3) were significantly improved by introducing a C=C bond adjacent to the alcohol moiety to give racemic (E)-pent-3-en-2-ol and 4-(E)-octen-3-ol, which were resolved with excellent selectivities (E >100 and 50, respectively). In addition, it was found that high stereodifferentiation between the E- and Z-configured double bonds occurred, as the corresponding (Z)-isomers were not converted. Similar selectivity-enhancing effects were observed with acetylenic analogs. (C) 2003 Elsevier Science Ltd. All rights reserved.
The stereoselective cyclopropanation of chiral allylic alcohols using a chiral dioxaborolane ligand: A new route to anti-cyclopropylmethanol derivatives
作者:AndréB Charette、Hélène Lebel、Alexandre Gagnon
DOI:10.1016/s0040-4020(99)00448-2
日期:1999.7
The diastereoselective cyclopropanation reaction of allylicalcohols in the presence of the chiral dioxaborolane ligand 1 was studied. Unprecedently high anti-selectivities were obtained with E-olefins when 2.2 equivalents of bis(iodomethyl)zinc and 1.1 equivalent of 1 were used.