761434-35-9Relevant articles and documents
Highly enantioselective epoxidation of 2-methylnaphthoquinone (vitamin K3) mediated by new cinchona alkaloid phase-transfer catalysts
Berkessel, Albrecht,Guixa, Maria,Schmidt, Friederike,Neudoerfl, Joerg M.,Lex, Johann
, p. 4483 - 4498 (2007)
In the area of catalytic asymmetric epoxidation, the highly enantioselective transformation of cyclic enones and quinones is an extremely challenging target. With the aim to develop new and highly effective phase-transfer catalysts for this purpose, we co
Enantioselective Ammonium Ylide Mediated One-Pot Synthesis of Highly Substituted γ-Butyrolactones
Drennhaus, Till,?hler, Laura,Djalali, Saveh,H?fmann, Svenja,Müller, Clemens,Pietruszka, J?rg,Worgull, Dennis
, p. 2385 - 2396 (2020/04/30)
An ammonium ylide mediated access towards trans-β,γ-disubstituted, all-trans-α,β,γ-trisubstituted, and α,α,β,γ-tetrasubstituted γ-butyrolactones bearing a broad variety of functionalities was developed. Starting from widely accessible benzylidene Meldrum's acid derivatives and α-bromo carbonyl compounds, γ-butyrolactones were obtained in yields between 32–99% with up to excellent diastereoselectivities (>95:5) via a DABCO-mediated [2+1] annulation. Utilization of enantiomerically pure cinchona alkaloid derivatives enables the first asymmetric ammonium ylide mediated method to provide (3R,?4R)-β,γ-disubstituted and (2R,?3R,?4R)-α,β,γ-trisubstituted γ-butyrolactones in moderate to good yields with up to very good enantiomeric ratios (97:3). The scalability of the transformation was proven while determining the absolute configuration. (Figure presented.).
Anti-Selective Asymmetric Nitro-Michael Reaction of Furanones: Diastereocontrol by Catalyst
Sekikawa, Tohru,Kitaguchi, Takayuki,Kitaura, Hayato,Minami, Tatsuya,Hatanaka, Yasuo
, p. 646 - 649 (2016/03/01)
Catalyst-controlled switching of diastereoselectivity from high syn-selectivity (>98/2 dr, syn) to anti-selectivity (up to 96/4 dr, anti) of the asymmetric nitro-Michael reaction of furanones is described. Anti-diastereoselectivity of the nitro-Michael reaction is very rare. With 0.1-5 mol % loadings of an epi-quinine catalyst, the reaction of 5-substituted 2(3H)-furanones with nitroalkenes smoothly proceeded to give the anti-Michael adducts in good yields (up to 95%) with excellent diastereo- and enantioselectivities (up to 96/4 dr, anti; up to 99% ee). DFT calculations support a model that accounts the high anti-diastereoselectivity. (Chemical Equation Presented).
