Treatment of both primary alcohols 1a,b and secondary amines 1c,d, tethered to a Michael acceptor with (R)-phenylethyl isocyanate in the presence of DBU gave in good yield and high stereoselection diastereomeric mixtures of oxazolidin-2-ones 2a,b and 3a.b and imidazolidin-2-ones 2c,d and 3c,d, respectively. The cyclisation reaction Was Studied computationally by ab initio quantum mechanical methods. The observed stereoselectivity was explained on the basis of the different stability of both anions and transition states leading to 2a and 3a, respectively. The usefulness of the method was proven by conversion of 2a into the enantiomerically Pure bioactive amino acid.
Homochiral oxazolidin-2-ones and imidazolidin-2-ones by tandem nucleophilic addition-conjugate addition / Ciclosi, M; Fava, C; Galeazzi, Roberta; Orena, M.. - In: TETRAHEDRON-ASYMMETRY. - ISSN 0957-4166. - STAMPA. - 15:12(2004), pp. 1937-1943. [10.1016/j.tetasy.2004.05.006]
Homochiral oxazolidin-2-ones and imidazolidin-2-ones by tandem nucleophilic addition-conjugate addition
GALEAZZI, ROBERTA;ORENA M.
2004-01-01
Abstract
Treatment of both primary alcohols 1a,b and secondary amines 1c,d, tethered to a Michael acceptor with (R)-phenylethyl isocyanate in the presence of DBU gave in good yield and high stereoselection diastereomeric mixtures of oxazolidin-2-ones 2a,b and 3a.b and imidazolidin-2-ones 2c,d and 3c,d, respectively. The cyclisation reaction Was Studied computationally by ab initio quantum mechanical methods. The observed stereoselectivity was explained on the basis of the different stability of both anions and transition states leading to 2a and 3a, respectively. The usefulness of the method was proven by conversion of 2a into the enantiomerically Pure bioactive amino acid.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
