A new asymmetric two-center phase-transfercatalyst was designed and a catalyst library containing more than 40 new two-center catalysts was constructed. The catalysts were applied in phase-transferalkylations and Michael additions to afford the corresponding products in up to 93% ee and 82% ee, respectively.
Enantioseparation of<i>P</i>-Stereogenic Secondary Phosphine Oxides and Their Stereospecific Transformation to Various Tertiary Phosphine Oxides and a Thiophosphinate
作者:Bence Varga、Péter Szemesi、Petra Nagy、Réka Herbay、Tamás Holczbauer、Elemér Fogassy、György Keglevich、Péter Bagi
DOI:10.1021/acs.joc.1c01364
日期:2021.11.5
Secondary phosphineoxides incorporating various aryl and alkyl groups were synthesized in racemic form, and these products formed the library reported in this study. TADDOL derivatives were used to obtain the optical resolution of these P-stereogenic secondary phosphineoxides. The developed resolution method showed a good scope under the optimized reaction conditions, as 9 out of 14 derivatives could
Kinetically Controlled Ring-Closing Metathesis: Synthesis of a Potential Scaffold for 12-Membered Salicylic Macrolides
作者:Yuji Matsuya、Sho-ichi Takayanagi、Hideo Nemoto
DOI:10.1002/chem.200800249
日期:2008.6.9
the synthesis of a 12-memberedsalicylicmacrolidescaffold, ring-closingmetathesis (RCM) of a omega-diene compound was planned. The stereochemical outcome of the RCM reaction changed depending on the type of Ru catalyst that was used; a "first-generation" Grubbs catalyst produced exclusively the E isomer and "second-generation" catalysts provided a mixture of the E and Z isomers under kinetic control
Novel tartrate-derived guanidine-catalyzed highly enantio- and diastereoselective Michael addition of 3-substituted oxindoles to nitroolefins
作者:Liwei Zou、Xiaoze Bao、Yuanyuan Ma、Yuming Song、Jingping Qu、Baomin Wang
DOI:10.1039/c4cc01817f
日期:——
The Michael addition of 3-substituted oxindoles to nitroolefins was catalyzed by a novel tartrate-derived guanidine in high yield with excellent diastereo- and enantioselectivity. This method showed an extraordinarily broad substrate scope in terms of both reaction partners.
Facile approach towards the synthesis of homochiral functionalised alcohols from 4-O-[(tert)-butyldimethylsilyl]-2,3-O-cyclohexylidene-l-threose of (l)-(+)-tartaric acid origin
作者:Angshuman Chattopadhyay、Bhaskar Dhotare
DOI:10.1016/s0957-4166(98)00282-1
日期:1998.8
(l)-(+)-Diethyl tartarate 2 has been transformed into the aldehyde 6. Grignard additions to 6 take place with moderate diastereoselectivity giving predominant formation of the anti products 8a–e. However, in each case the diastereoalcohols are easily separable by column chromatography giving rise to the formation of a series of functionalised homochiral alcohols 7 and 8. On the other hand Zn mediated allylation