168784-33-6Relevant academic research and scientific papers
New Axially Chiral Sulfur Compounds: Synthesis and Conformational Stability of Enantiopure 4,4'-Biphenanthrene-3,3'-dithiol and Related Atropisomeric Derivatives
Dore, Antonio,Fabbri, Davide,Gladiali, Serafino
, p. 779 - 788 (1995)
Enantiopure (R)- and (S)-4,4'-biphenanthrene-3,3'-dithiol 1a has been prepared for the first time through a synthetic procedure involving in the key stop a stereoconservative Newman-Kwart thermorearrangement of the bis-N,N-dimethylthiocarbamoyl ester of (R)- and (S)-biphenanthrol 2b, respectively.The atropisomeric conformations of 1a are not, interconverted even at temperatures as high as 285 deg C, whereas the related biphenanthrothiophene 3 is completely racemized in a few minutes at 250 deg C.The axially chiral backbone of 1a has been incorporated in a set of novel C2 symmetry sulfur reagents suitable for a variety of stereoselective reactions.
Synthesis of structurally modified atropisomeric biaryl dithiols. Observations on the Newman-Kwart rearrangement
Cossu, Sergio,De Lucchi, Ottorino,Fabbri, Davide,Valle, Giovanni,Painter, Gavin F.,Smith, Robin A.J.
, p. 6073 - 6084 (2007/10/03)
The preparation of a number of biaryldithiols from biaryldiols is discussed. A key reaction is the Newman-Kwart thermorearrangement of bisthiocarbamates and crucial variables of temperature and reaction time have been identified. Alternative approaches to 3,3'-disubstituted dithiols via ortho metallation are presented. The benefit of using such disubstituted compounds is illustrated with representative examples of the stereochemical features of the derived carbanions in reactions with prochiral electrophiles.
