Lipase-catalyzed enantioselective desymmetrization of prochiral 3,3-bis(hydroxymethyl)oxindoles
作者:Shuji Akai、Toshiaki Tsujino、Tadaatsu Naka、Kouichi Tanimoto、Yasuyuki Kita
DOI:10.1016/s0040-4039(01)01547-7
日期:2001.10
Oxindoles 3b–d (91–98% ee) having a chiral quaternary carbon center at the C-3 position were prepared from readily available oxindoles 5a–c in 50–64% overall yields, in which an enantioselectivedesymmetrization of prochiral 1,3-diols 2b–d using a Candida rugosa lipase (Meito OF) and 1-ethoxyvinyl 2-furoate 1 was employed as the key step.
羟吲哚3b的- d(91-98%ee)的具有在C-3位手性季碳中心从容易得到的羟吲哚制备了图5a - Ç在50-64%总产率,其中前手性的1,3-对映选择性desymmetrization采用皱纹念珠菌脂肪酶(Meito OF)和2-糠酸1-乙氧基乙烯基酯1制成的2- b - d二醇是关键步骤。
Enantiodivergent Preparation of Optically Active Oxindoles Having a Stereogenic Quaternary Carbon Center at the C3 Position via the Lipase-Catalyzed Desymmetrization Protocol: Effective Use of 2-Furoates for Either Enzymatic Esterification or Hydrolysis
作者:Shuji Akai、Toshiaki Tsujino、Emi Akiyama、Kouichi Tanimoto、Tadaatsu Naka、Yasuyuki Kita
DOI:10.1021/jo035749h
日期:2004.4.1
the C3 position and a different N-protective group, were readily prepared by the lipase-catalyzed desymmetrization protocol. Thus, the transesterification of the prochiral diols 3a−h with 1-ethoxyvinyl 2-furoate 5 was catalyzed by Candida rugosa lipase to give (R)-(+)-2a−h (68−99% ee), in which the use of a mixed solvent, iPr2O (diisopropyl ether)−THF, was crucial. The same lipase also effected the
Efficient Lipase-Catalyzed Enantioselective Desymmetrization of Prochiral 2,2-Disubstituted 1,3-Propanediols and Meso 1,2-Diols Using 1-Ethoxyvinyl 2-Furoate
作者:Shuji Akai、Tadaatsu Naka、Tetsuya Fujita、Yasushi Takebe、Toshiaki Tsujino、Yasuyuki Kita
DOI:10.1021/jo010587f
日期:2002.1.1
desymmetrization of prochiral 2,2-disubstituted 1,3-propanediols was developed using 1-ethoxyvinyl 2-furoate 1b, for which the well-known method using vinyl or isopropenyl acetate has had limited success due to low reactivity and easy racemization of the products through acyl group migration. The reagent 1b is highlyreactive and converts various prochiral 1,3-diols to the monoesters having a chiral quaternary
Enantiodivergent Synthesis of Either Enantiomer of ABCDE-Ring Analogue of Antitumor Antibiotic Fredericamycin A via Intramolecular [4 + 2] Cycloaddition Approach
作者:Shuji Akai、Toshiaki Tsujino、Nobuhisa Fukuda、Kiyosei Iio、Yoshifumi Takeda、Ken-ichi Kawaguchi、Tadaatsu Naka、Kazuhiro Higuchi、Yasuyuki Kita
DOI:10.1021/ol016696y
日期:2001.12.1
[reaction: see text] An intramolecular enantiodivergent synthesis of both enantiomers of the ABCDE-ring analogue 22 of fredericamycin A is reported. Key steps involve an intramolecular [4 + 2] cycloaddition of 17 and an aromaticPummerer-typereaction of 19. A lipase-catalyzed enantioselective desymmetrization of prochiral diol 2 using 1-ethoxyvinyl 2-furoate 3 led to the pivotal intermediate (R)-4
The asymmetric totalsynthesis of the potent antitumor antibiotic fredericamycin A ((S)-1) was achieved by the intramolecular [4+2] cycloaddition of the silylene-protected styrene derivative (S)-7 followed by the aromatic Pummerer-type reaction of the sulfoxide (S)-5. Although we had already succeeded in the totalsynthesis of racemic 1 by the same approach, synthesis of its asymmetric version was