Sulfur dioxide hetero-Diels-Alder additions

Since the first report in 1914 of the formation of a butadiene-sulfur dioxide adduct [538], much work has been carried out on the reaction of conjugated dienes with sulfur dioxide and its applications in synthetic strategies. Two pathways can and have been observed a cheletropic reaction (to 2s + ir 4s) yielding 3-sulfolenes and (4 -ns + tt 2s) hetero-Diels-Alder addition yielding sultines (see [539] and [540] and references... 

Vogel and co-workers have used 1 as double chain elongation synthon in their synthesis of long chain polypropionate fragments (eq 48). Their approach is based on an one-pot reaction cascade which involves hetero-Diels-Alder addition of electron-rich l-alkoxy-3-acyloxy-l,2-dienes (e.g., 25) to sulfur dioxide, subsequent ionization into zwitterionic intermediates (e.g., 26), then reaction of the latter with allylsilanes. The final step of this sequence is the retro-ene desulfinylation of an intermediate allylsilyl sulfinate (e.g., 27) to produce useful synthetic intermediates containing two more stereogenic centers (e.g., 28). 

Hetero-Diels-Alder Additions of Sulfur Dioxide... 

SCHEME 22.40. Examples of hetero-Diels-Alder additions of sulfur dioxide. 

Deguin B, Vogel P. Hetero-Diels-Alder addition of sulfur-dioxide to 1,3-dienes-suprafaciality, regioselectivity, and stereoselectivity. J. Am. Chem. Soc. 1992 114(23) 9210-9211. 

Roversi E, Scopelliti R, Solari E, Estoppey R, Vogel P, Brafia P, Menendes B, Sordo JA. The hetero-Diels-Alder addition of sulfur dioxide to 1-fluorohuta-l,3-dienes the sofa conformations preferred by 6-fluorosultines (6-fluoro-3,6-dihydro-l,2-oxathiin-2-oxides) enjoy enthalpic and conformational anomeric effects. Chem. Eur. J. 2002 8... 

Roberson, M., Jepsen, A. S., Jorgensen, K. A. On the mechanism of catalytic enantioselective hetero-Diels-Alder reactions of carbonyl compounds catalyzed by chiral aluminum complexes-a concerted, step-wise or Mukaiyama-aldol pathway. Tetrahedron 2001, 57, 907-913. Monnat, F., Vogel, P., Rayon, V. M., Sordo, J. A. Ab Initio and Experimental Studies on the Hetero-Diels-Alder and Cheletropic Additions of Sulfur Dioxide to (E)-I-Methoxybutadiene A Mechanism Involving Three Molecules of S02. J. Org. Chem. 2002, 67, 1882-1889. 

Monnat, F., Vogel, P., Sordo, J. A. Hetero-Diels-Alder and cheletropic additions of sulfur dioxide to 1,2-dimethylidenecycloalkanes. Determination of thermochemical and kinetics parameters for reactions in solution and comparison with estimates from quantum calculations. Helv. Chim. Acta 2002, 85, 712-732. 

MO calculations of the reaction of 3,4-bis(methoxycarbonyl)-l,2-dithiete (150) with alkenes to produce 2,3-dihydro-1,4-dithiins (152) confirmed that the reaction is a reverse-electron-demand hetero-Diels-Alder type between the valence isomer 1,2-bis(methoxycarbonyl)ethane-l,2-dithione (151) and the dienophiles (Scheme 58). Sulfur dioxide has been shown to promote its hetero-Diels-Alder and chelotropic additions to 1,2-dimethyUdenecyclohexane. The competition between hetero-Diels-Alder and chelotropic addition of sulfur dioxide with substituted 1,3-dienes has been investigated by studying the theoretical and experimental effects on the relative stability of sultines and sulfolenes. ... 

---