(Ss)-5-ethoxy-3-p-tolylsulfinylfuran-2(5H)-ones as chiral dipolarophiles: First asymmetric cycloaddition of diazomethane to vinyl sulfoxides

(Z)-3-p-Tolylsulfinylacrylonitriles as Chiral Dipolarophiles: Reactions with Diazoalkanes

“…Since the reactivity of diazoalkanes with acrylonitriles is lower than that of compound 1a (see above), we must conclude that the sulfinyl group increases the dipolarophilic reactivity with these 1,3-dipoles. The same conclusion had also been reached from the results obtained for 3- p -tolylsulfinyl-5-alkoxyfuranones with diazoalkanes . Otherwise, the reactivity of compounds 1 as dipolarophiles is clearly higher than their dienophilic reactivity.…”

“…Since this problem was minimized with dipolarophiles lacking a hydrogen atom at a cis -arrangement with respect to the sulfinyl group, the structure of the easily obtained ( Z )-3- p -tolylsulfinylacrylonitriles suggested their potential efficiency as chiral dipolarophiles. Taking into account that the sulfinyl group was shown to be very efficient in increasing the reactivity of some dipolarophilic moieties with diazoalkanes, we decided to begin our study with these 1,3-dipoles, to achieve a new entry to enantiomerically pure Δ 1 -cyanopyrazolines, whose structures are much less frequently reported in the literature than those of their corresponding Δ 2 -analogues . The asymmetric synthesis of pyrazolines has been studied mainly from cyclic 5,8 and much less from acyclic alkenes. 4b,8c, …”

1,3-Dipolar cycloadditions of 2-thio-3-chloroacrylamides with diazoalkanes

“…5, 6 A series of reports over the past 15 years from Garcia Ruano's group discuss in detail 1,3-dipolar cycloadditions of diazomethane and diazoethane to vinyl sulfoxides of direct relevance to this work. [7][8][9][10][11][12] However, the presence of the 3-chloro substituent in the dipolarophiles in the current work potentially has a significant electronic effect on their reactivity, and more importantly, leads to chloro-substituted heterocycles, where the presence of the chloride substituent offers considerable synthetic potential and diversity via substitution and coupling processes.…”

Recent developments in chiral non-racemic sulfinyl group chemistry in asymmetric synthesis

“…Garcia Ruano has studied the reaction of diazomethane with sulfinylfuranones 99. 75 The resulting pyrazolines 100 were obtained as single diastereomers in quantitative yield. These compounds were stable and fully characterised and could be pyrolysed by heating in toluene to afford the corresponding methyl-substituted furanones 101 (Scheme 38).…”