Tin(iv) chloride mediated (3 + 2) annulation of trans-2-aroyl-3-styrylcyclopropane-1,1-dicarboxylates with nitriles: diastereoselective access to 5-vinyl-1-pyrroline derivatives

Abstract

A (3 + 2) annulation of trans-2-aroyl-3-styrylcyclopropane-1,1-dicarboxylates with nitriles is reported for the diastereoselective synthesis of 5-vinyl-1-pyrroline derivatives in 60–88% yields.

Tandem Dearomative/Rearomative (3 + 2) Annulation of Aroyl-Substituted Donor–Acceptor Cyclopropanes with Benzothiazoles

“…The Yang group has reported the (3 + 2) annulations of such aroyl-substituted DACs with aldehydes and ketones to give various tetrahydrofurans and with isothiocyanates to afford 2-iminodihydrothiophenes . In this line, our group has also reported that aroyl-substituted DACs undergo (3 + 2) annulation with nitriles to give 1-pyrrolines and (3 + 3) annulation with mercaptoacetaldehyde to afford tetrahydrothiopyranols . The presence of the extra aroyl group in those DACs strongly influences the outcome of the reactions and also makes the products of the reactions have unique applications .…”

“…When a cyclopropane having a p -nitrophenyl ring as Ar 1 was used in the reaction, it did not undergo any change (entry 7). The reason may be the inability of the electron-withdrawing p -nitrophenyl group in stabilizing the positive charge of the respective 1,3-dipolar intermediate that would be formed during the course of the (3 + 2) annulation. , In case of a cyclopropane having a 2-thienyl group as Ar 1 , the reaction afforded the dearomatized product 8a , instead of the respective aromatized product, possibly due to the π-electron-rich nature of the thienyl ring (entry 8). We also employed DACs containing different substituents on the Ar 2 ring in the reaction.…”

The Cloke–Wilson rearrangement of aroyl-substituted donor–acceptor cylopropanes containing arylethyl donors

“…Apart from the regular D–A substituents at the vicinal positions, the introduction of an additional substituent at the third position of the cyclopropane ring leads to intriguing outcomes in the reactions of D–A cyclopropanes, as exemplified by aroyl- and nitro-substituted D–A cyclopropanes reported from our laboratory. 5 Moreover, a small change in the structure of D–A cyclopropanes results in a large variation in their reactivity pattern. For example, D–A cyclopropanes 1 having an aryl group (Ar 1 ) as the donor, when treated with SnCl 4 , gave 2-pyrones 2 (Scheme 1, eqn (1)), 5 b whereas similar cyclopropanes 3 having a styryl group (Ar 1 CHCH) as the donor afforded cyclopentenes 4 when treated with the same Lewis acid (Scheme 1, eqn (2)).…”