189758-61-0Relevant academic research and scientific papers
Pd-catalyzed cleavage of benzylic nitro bonds: New opportunities for asymmetric synthesis
Fessard, Thomas C.,Motoyoshi, Hajime,Carreira, Erick M.
, p. 2078 - 2081 (2008/02/13)
Without a trace: Benzylic nitroalkanes are reduced to the corresponding parent alkanes in good yields by using a simple procedure involving heterolytic C-N bond cleavage (see scheme). Traceless removal of the nitro group leaves behind a stereogenic center that may otherwise be difficult to install. This reaction significantly expands the scope of building blocks that can be accessed. (Chemical Equation Presented)
Stereoselective conjugate addition of benzyl phenylsulfonyl carbanions to enoates derived from D-mannitol
Ferreira, Andre R. G.,Vilela, Guilherme V. M. De A.,Amorim, Mauro B.,Perry, Katia P.,Da Silva, Antonio J. R.,Dias, Ayres G.,Costa, Paulo R. R.
, p. 4013 - 4018 (2007/10/03)
The conjugate addition of benzylic phenylsulfonyl carbanions (2a′-d′) to enoates derived from D-(+)-mannitol (E- or Z-1a-c) was studied using THF and THF/HMPA as solvent. Under kinetic conditions (-78 °C), enoate E-1a,b led to a mixture of syn-(R,S) and a
Syn-Selective Michael Addition of Nitromethane Derivatives to Enoates Derived from (R)-(+)-Glyceraldehyde Acetonide
Costa, Jeronimo S.,Dias, Ayres G.,Anholeto, Aline L.,Monteiro, M?nica D.,Patrocinio, Vera L.,Costa, Paulo R.R.
, p. 4002 - 4006 (2007/10/03)
We report the syn-selective Michael addition of a series of substituted primary and secondary nitromethane derivatives 4a-g to chiral enoates (Z)-2a and (E)-2a in the presence of TBAF·3H2O or DBU. Regardless of the base employed, adducts syn-5a-g were obtained in good de (80-100%) from the reactions of 4a-g with (Z)-2a. However, in the addition to (E)-2a, the syn-diastereo-selectivities depended on the structure of the nucleophile (80-90% de for nitromethane (4a), 80% de for phenylnitromethane (4g), 50 and 34% de for the primary nitromethane derivatives 4b and 4d, and 0 and 6% de for the secondary nitromethane derivatives 4c and 4f). A mixture of epimers (2:1/1:1) was obtained at the chiral center bearing the nitro group in 5b and 5d-g. The syn/anti ratio C-3,C-4 is kinetically controlled, while the epimeric ratio at the CNO2 chiral center (C-1′) seems to be thermodynamicaliy controlled. Adducts 5a,b,c,g were transformed into the respective cis-β,γ-disubstituted γ-butyrolactones 6a, 7, 9a, and 9c. A mechanistic rationale to explain the observed diastereoselectivities is proposed.
