ChemInform Abstract: New Cycloadditions in Organic Sulfur Chemistry

Abstract

ChemInform Abstract (38 refs.).

Regio- and stereoselectivity of [2?+?3] cycloaddition of (E)-?-nitrostyrenes to (Z)-C,N-diphenylnitrone in the light of AM1 and AM1/COSMO calculations

“…These changes, when combined with the ca 30% increase in t, suggest that increasing the alkene electrophilicity should favor the reaction course according to a zwitterionic mechanism. 17,18 Actually, when nitrostyrene 1c was involved in calculations as dipolarophile, between structures R and P four stationary structures were found on paths A and B (Figs 4 and 5, Table 2). Initially, as in the gas phase, interaction of 1c with 2 leads with any activation barrier to supermolecules LM, which are similar to those obtained for the other two pairs of reactants.…”

Dichotomy of 1,3-dipolar cycloreversions in a tetrasubstituted 2,5-dihydro-1,3,4-thiadiazole

“…In contrast to the experiment in toluene, 52% of 10 was still unconsumed after 4 months. The negative effect of solvent polarity on the rate of N 2 elimination, observed for several dihydrothiadiazoles [5], is not large enough to explain the big difference in reaction progress; probably the low solubility of 10 in acetonitrile is responsible.…”

“…A modest negative influence of solvent polarity has been observed for the N 2 elimination of many 2,5-dihydro-1,3,4-thiadiazoles [5].…”

Rolf Huisgen: A Gentleman Scholar with Energy and Passion

“…As Rolf has said, The number of organic compounds is potentially infinite. Nowhere does one feel confronted with this profusion to a higher extent than in heterocyclic chemistry [3] . Chemistry at the University of Munich has a long and glorious tradition.…”

“…Likely, his name will be associated with his most popular discovery and development: 1,3-dipolar cycloaddition reactions, which, characteristically for him, had its origin in mechanistic considerations. These reactions opened the sluices and a flood of five-membered heterocycles broke loose [3] . As Rolf has said, The number of organic compounds is potentially infinite.…”