π-Face-selective hetero Diels–Alder reactions of 3, 4-di-tert-butylthiophene 1-oxide. An excellent trapping reagent for thioaldehydes and thioketones
J Takayama, S Fukuda, Y Sugihara, A Ishii…
Index: Takayama, Jun; Fukuda, Seiko; Sugihara, Yoshiaki; Ishii, Akihiko; Nakayama, Juzo Tetrahedron Letters, 2003 , vol. 44, # 28 p. 5159 - 5162
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Citation Number: 16
Abstract
Hetero Diels–Alder reactions of 3, 4-di-tert-butylthiophene 1-oxide (1) with thioaldehydes and thioketones take place exclusively, except the reaction with thiobenzophenone, at the syn-π-face of 1 with respect to the S O bond. The π-face selectivity was explained in terms of the extent of conformational changes of 1 that are brought about in the process to the transition states.
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