81650-81-9Relevant academic research and scientific papers
Nucleophilic additions of lithiated allylphenylsulfone to nitrones: Experimental and theoretical investigations
Merino, Pedro,Mannucci, Vanni,Tejero, Tomás
, p. 3335 - 3347 (2005)
The nucleophilic addition of lithiated allylphenylsulfone to nitrones at -80°C proceeds exclusively α to the phenylsulfonyl group affording anti adducts in high yield. At 0°C isoxazolidines are obtained with complete all-trans selectivity. The formation of these compounds involves isomerization of the allylsulphonyl moiety to give a transient vinylsulfone that then undergoes a subsequent intramolecular Michael addition. The addition to several nitrones has been studied and theoretical calculations have been refined to accurately explain the selectivity of the allylation reaction.
Experimental and Theoretical Investigation on the Cycloadditions of Nitrile Oxides, Nitrones, and Diazoalkanes with Acyclic Vinyl Sulphones and Thiet 1,1-Dioxide
Benedetti, Pier G. De,Quartieri, Simona,Rastelli, Augusto,Amici, Marco De,Micheli, Carlo De,et al.
, p. 95 - 100 (2007/10/02)
Diazoalkanes, nitrile oxides, and nitrones cycloadd thiet 1,1-dioxide showing regiochemical characteristics markedly different from those observed for acyclic vinyl sulphones.The charge-transfer stabilization energy, calculated according to the Klopman-Salem pertubational approach in the CNDO/2 approximation, is able to account for the experimantal trends of the isomer ratios.An analysis of the calculations performed for cis-syn-vinyl sulphones explains the change of regiochemistry in the reactions of thiet 1,1-dioxide as due to its blocked cis-syn-structure which does not happen in the 'open' vinyl sulphones.Unsuccessful predictions obtained with the frontier orbital approximation are discussed.
