Michael Additions versus Cycloaddition Condensations with Ethyl Nitroacetate and Electron-Deficient Olefins
作者:Elena Trogu、Francesco De Sarlo、Fabrizio Machetti
DOI:10.1002/chem.200802652
日期:2009.8.10
nitroacetate (1) reacts with electron‐poor olefins in the presence of a base to give either the Michael adducts 3 or the isoxazoline cycloadducts 4, resulting from water elimination. The proportions of the two products depend on the reaction conditions and change in the course of the process. Kinetic profiles for the two reactions show that the cycloaddition‐condensations require long induction times that dramatically
Conjugate Addition versus Cycloaddition/Condensation of Nitro Compounds in Water: Selectivity, Acid-Base Catalysis, and Induction Period
作者:Luca Guideri、Francesco De Sarlo、Fabrizio Machetti
DOI:10.1002/chem.201202698
日期:2013.1.7
react in water as in chloroform with electron‐deficient dipolarophiles to give condensation or conjugate addition products under basecatalysis. In general, high selectivity towards condensation is observed in water, with shorter induction periods than in chloroform. In water, condensations slowly occur even without base; kinetic profiles evidence the catalytic effect of the base, which should be related
TICOZZI, CALIMERO;ZANAROTTI, ANTONIO, TETRAHEDRON LETT., 29,(1988) N 47, C. 6167-6170
作者:TICOZZI, CALIMERO、ZANAROTTI, ANTONIO
DOI:——
日期:——
Baker's yeast reduction of 5-acetyl-2-isoxazolines synthesis of enantiomerically pure 2,3-dihydroxy ketones and 1,2,4-triols
作者:Calimero Ticozzi、Antonio Zanarotti
DOI:10.1016/s0040-4039(00)82296-0
日期:——
5-acetyl-2-isoxazolines to 5-ethanol-2-isoxazolines in high yields and high enantiomeric excess. Subsequent ring hydrogenolysis of the alcohols thus produced leads to enantiomerically pure 2,3-dihydroxy ketones and 1,2,4-triols.
Stereoselective synthesis of β-substituted-l-threonines from enantiopure 5-acetyl-2-isoxazolines
作者:Giuseppe Cremonesi、Piero Dalla Croce、Alessandra Forni、Maddalena Gallanti、Concetta La Rosa
DOI:10.1016/j.tet.2011.02.055
日期:2011.4
ted (5S)- and (5R)-5-acetyl-2-isoxazolines were obtained from the corresponding racemic mixtures by means of an enzymatic reduction with baker’s yeast, followed by the separation of the enantiopure syn- and anti-alcohols and oxidation of the alcohol group. The reaction between these ketones and (2R)-Schöllkopf’s bislactim ether azaenolate was studied: using (5S)- and (5R)-3-methyl derivatives, two