TY - JOUR
T1 - Synergic effect of vicinal stereocenters in [3 + 2] cycloadditions of carbohydrate azadipolarophiles and mesoionic dipoles
T2 - Origin of diastereofacial selectivity
AU - Avalos, M.
AU - Babiano, R.
AU - Cintas, P.
AU - Clemente, F. R.
AU - Gordillo, R.
AU - Jiménez, J. L.
AU - Palacios, J. C.
PY - 2001/7/27
Y1 - 2001/7/27
N2 - The intermolecular [3 + 2] cycloaddition of carbohydrate-derived 1,2-diaza-1,3-butadienes and 1,3-thiazolium-4-olates provides a conceptual basis for the problem of diastereofacial preference in the acyclic series of unsaturated sugars. Experimental results employing a side chain of D-arabino configuration have shown the stereodifferentiation exerted by the first stereogenic center that renders the Re,Re face of the acyclic sugar-chain azadiene eligible for cycloaddition (J. Org. Chem. 2000, 65, 5089). The results of the present work, now utilizing an alternative framework of D-lyxo configuration, evidence the discriminating power of the second stereogenic carbon, which induces the preferential approach to the Re,Si face of the heterocyclic dipole. This scheme of face selectivity is also grounded in theoretical calculations at a semiempirical level. In addition to dihydrothiophenes, which are the expected products of the [3 + 2] cycloaddition, bicyclic systems based on dihydrothieno[2,3-c]piperidine skeleton can also be obtained.
AB - The intermolecular [3 + 2] cycloaddition of carbohydrate-derived 1,2-diaza-1,3-butadienes and 1,3-thiazolium-4-olates provides a conceptual basis for the problem of diastereofacial preference in the acyclic series of unsaturated sugars. Experimental results employing a side chain of D-arabino configuration have shown the stereodifferentiation exerted by the first stereogenic center that renders the Re,Re face of the acyclic sugar-chain azadiene eligible for cycloaddition (J. Org. Chem. 2000, 65, 5089). The results of the present work, now utilizing an alternative framework of D-lyxo configuration, evidence the discriminating power of the second stereogenic carbon, which induces the preferential approach to the Re,Si face of the heterocyclic dipole. This scheme of face selectivity is also grounded in theoretical calculations at a semiempirical level. In addition to dihydrothiophenes, which are the expected products of the [3 + 2] cycloaddition, bicyclic systems based on dihydrothieno[2,3-c]piperidine skeleton can also be obtained.
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U2 - 10.1021/jo015654k
DO - 10.1021/jo015654k
M3 - Article
C2 - 11463267
AN - SCOPUS:0035958485
SN - 0022-3263
VL - 66
SP - 5139
EP - 5145
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
IS - 15
ER -