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

Abstract

[reaction: see text] The dipolarophilic reactivity of enantiopure (Z)-3-p-tolylsulfinylacrylonitriles (1) has been evaluated with diazoalkanes. 3-Cyanopyrazoles are obtained when R = H, but with R = alkyl (Bn, n-Bu, and t-Bu) only one cycloadduct (4 or 5) is formed in high yield under mild conditions, therefore evidencing a complete control of the regioselectivity and the endo/exo and pi-facial selectivities. These reactions are a new straightforward entry to the synthesis of pyrazolines and related structures and reveal the excellent dipolarophilic features of (Z)-sulfinylacrylonitriles.

Stereoselective Synthesis of 2-Thio-3-Chloroacrylamides and Investigation of their Reactivity

“…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. [27][28][29][30][31][32] 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 chloro substituent offers considerable synthetic potential and diversity via subsequent substitution and coupling processes.…”

Asymmetric 1,3-dipolar reactions of cyclic vinyl p-tolyl sulfimines with diazoalkanes

“…The absolute configuration of 6 was finally corroborated by chemical correlation with compound 11 (obtained by reaction of (Z)-3-p-tolylsulfinyl-2-n-butylacrylonitrile with diazoethane), 7 whose configuration was already known by X-ray diffraction. Thus, reduction of the sulfilimine functionality by treatment of a mixture of 6 and 7 with LiAlH 4 afforded an epimeric mixture of sulfenylcarboxamides, 8 and 8'.…”

Search for ideal sulfinyl dienophile and dipolarophile

“…The first studied 1,3-dipole was diazomethane [22]. The reactions took place under very mild conditions (see Fig.…”