Chiral 2,2-disubstituted 3-hydroxycycloketones are highly desired intermediates for the construction of complex molecules with multiple chiral centres. Structure-guided directed evolution of the alcohol dehydrogenase TbADH from Thermoanaerobacter brockii was performed to enhance the enzyme activity toward ethyl secodione (1a) in an attempt to use isopropanol for substrate-coupling cofactor regeneration
Comparative reductive desymmetrization of 2,2-disubstituted-cycloalkane-1,3-diones
作者:Jeremy M. Carr、Timothy S. Snowden
DOI:10.1016/j.tet.2008.01.065
日期:2008.3
Reductive desymmetrization of 2-methyl-2-substituted-cycloalkane-1,3-diones can be effected using either NaBH(4) in DME or lithium tri-tert-butoxyaluminum hydride (LTBA) in THF at -60 degrees C. The former is a new approach that offers slightly greater diastereoselectivity in the reduction of 2,2-disubstituted-cyclopentane- 1,3-diones while LTBA is superior with 2,2-disubstituted-cyclohexane- 1,3-diones. Both conditions minimize subsequent reduction to diols thereby furnishing high yields of 1,3-ketols. Particularly rapid monoreductions are observed with 2-methyl-2-nitroethylcyclopentane-1,3-dione and 2-cyanoethyl-2-methylcyclopentane-1,3-dione when treated with NaBH(4) in DME at -60 degrees C. As expected, diastereoselectivity varies considerably with the substitution at C-2. (C) 2008 Elsevier Ltd. All rights reserved.
A novel annulation method for the synthesis of some nitrogen-containing heterocycles: The synthesis of (±)-heliotridane and (±)-nuphar indolizidine
作者:Takeshi Ohnuma、Masayasu Tabe、Keiko Shiiya、Yoshio Ban、Tadamasa Date
DOI:10.1016/s0040-4039(00)88313-6
日期:——
BROOKS, D. W.;MAZDIYASNI, H.;GROTHAUS, P. G., J. ORG. CHEM., 52,(1987) N 15, 3223-3232
作者:BROOKS, D. W.、MAZDIYASNI, H.、GROTHAUS, P. G.
DOI:——
日期:——
Semirational Engineering of a Thermostable Carbonyl Reductase for the Precision Synthesis of (2<i>R</i>,3<i>R</i>)-2-Methyl-2-benzyl-3-hydroxycyclopentanone and Its Analogues