Synthesis of 2 or 3-(hetero)aryl pyrazolo[1,5-a]pyridines through [3 + 2] cycloaddition ofN-aminopyridine with β-nitrostyrenes followed byin situdenitration under metal-free and mild conditions are described.
Highly stereoselective oxy-Michael additions to α,β-disubstituted nitro olefins: asymmetric synthesis of pseudo-norephedrine derivatives and THP* protected α-hydroxy ketones
作者:David J. Buchanan、Darren J. Dixon、Felix A. Hernandez-Juan
DOI:10.1039/b406804c
日期:——
delta lactol undergoes efficient oxy-Michael addition to alpha,beta-disubstituted nitroolefins to give the THP* protected Henry products with excellent (95-->98% de) stereocontrol at the beta-position and moderate (up to 3 : 1) stereocontrol at the alpha-position in favour of the syn-diastereoisomer. Nitro group reduction with in situN-Boc protection and THP* removal provides alpha,beta-disubstituted
Boberg, Friedrich; Garburg, Karl-Heinz; Goerlich, Karl-Joachim, Liebigs Annalen der Chemie, 1985, # 2, p. 239 - 250
作者:Boberg, Friedrich、Garburg, Karl-Heinz、Goerlich, Karl-Joachim、Pipereit, Eberhard、Ruhr, Maria
DOI:——
日期:——
Henry condensation under high pressure 2. Effect of aromatic aldehyde type and pressure on the yield of ?-nitrostyrenes and secondary processes
作者:N. E. Agafonov、I. P. Sedishev、A. V. Dudin、A. A. Kutin、G. A. Stashina、V. M. Zhulin
DOI:10.1007/bf00965433
日期:1991.2
Condensation of aromatic aldehydes (I)-(XX) with EtNO2 and n-PrNO2 in AcOH in the presence of AcONH4 or i-BuNH2 gives primarily omega-nitrostyrenes (Ia, b)-(XXa, b) and small quantities of nitriles (Ic)-(XXc), oximes (Id)-(XXd), and ketones (Ie, f)-(XXe, f). The yields of (Ia, b)-(XXa, b) at P = 1 atm are higher for acceptor substituents on the aromatic ring whereas at P = 10 kbar, they are higher for donor substituents. High pressures suppress the formation of (Ic-f)-(XXc-f) and the Z-isomers of (Ia, b)-(XXa, b). The high pressure technique is especially useful in the preparation of donor-substituted (Ia, b)-(XXa, b) which are intermediates in the synthesis of the psychotropic beta-phenylethylamines.