1574-34-1Relevant articles and documents
What is the reason for the difference in Diels-Alder reactivity of isomeric substituted dienes? A case involving 1,3-dienylboronates
Ohanessian, Gilles,Six, Yvan,Lallemand, Jean-Yves
, p. 1143 - 1148 (2007/10/03)
Correspondence and reprints Semi-empirical and ab initio calculations were run to account for the differences in reactivity of 1,3-dienylboronates 1, (E)-2 and (Z)-2 in the Diels-Alder cycloaddition with methyl acrylate. The results show that the s-cis conformation is accessed from the most stable s-trans, as easily for the unreactive (Z)-2 isomer as it is for the reactive (E)-2 isomer and for 1. Furthermore, the diene geometries and TT molecular orbitals in the s-cis conformation are not sufficiently affected by (Z) versus (E) substitution to explain the experimental observations. These results lead to the conclusion that variations in diene reactivity are most probably governed by steric repulsions in the Diels-Alder transition state in the case of (Z)-2. Diels-Alder / 1,3-dienylboronate / diene conformation / isoprene / steric constraint / ab initio calculation Eisevier,.
REACTIONS OF NITROGEN NUCLEOPHILES WITH 1-BROMOALLENES: REGIOSELECTIVE SYNTHESIS OF PROPARGYLAMINES
Geri, Roberto,Polizzi, Carmela,Lardicci, Luciano,Caporusso, Anna Maria
, p. 241 - 248 (2007/10/02)
The results of a study on the reactivity of 3-alkyl- and 3,3-dialkyl-1-bromo-1,2-dienes 2 towards nitrogen nucleophiles, such as aqueous ammonia, lithium amide, aliphatic and aromatic amines allowed us to propose new methods for the synthesis of propargylamines, 1, with an available acetylenic hydrogen.The regio- and the stereoselectivity of these reactions are examined and possible mechanisms are discussed.