Synthesis of Vinyl Cyclopropanes via Anion Relay Cyclization

Abstract

A method where an allyl alcohol is formed from a Tsuji-Trost allylation between a vinyl epoxide and an acyl containing nucleophile is described. Subsequently, a retro-Claisen condensation is utilized as a means of through-space anion relay. The anion relay results in the formation of a reactive carbanion and simultaneously activates an allylic alcohol toward intramolecular Tsuji-Trost cyclopropanation. Hence, in one pot, Tsuji-Trost allylation, retro-Claisen activation, and Tsuji-Trost cyclopropanation are combined to access synthetically useful vinyl cyclopropanes from vinyl epoxides using a mild and operationally simple procedure.

Formal [5+2] Cycloaddition of Vinyloxiranes with Oxazol‐5‐(4H)‐ones: A Facile Approach for Construction of Seven‐Membered Lactones

“…Substituted vinyloxiranes 1a – 1e were synthesized according to the reported procedures. [7c], Oxazol‐5‐(4 H )‐ones 2a – 2m were prepared according to literature procedures …”

“…On the one hand, by acting as 1,3‐ or 1,5‐dipolar system, they can undergo the [3+2],[3c], [5+2],[3a] [5+3] and [5+4] cycloadditions with structurally varied unsaturated functionalities (Scheme , 1–4). On the other hand, they can undergo the alkylation reactions with diversely functionalized nucleophiles . Presently, only several [5+ n ] cycloaddition of vinyloxiranes ( n = 2, 3 & 4) have been disclosed, and these previous [5+ n ] cycloadditions have fully been unexplored in the preparation of the medium‐sized lactones.…”

Stereoselective Synthesis of Fused Vinylcyclopropanes by Intramolecular Tsuji–Trost Cascade Cyclization

“…γ-lactones and γ-lactams . Furthermore, a Tsuji–Trost allylation/retro-Claisen/Tsuji–Trost cyclization sequence was recently reported to afford a range of vinylcyclopropanes . In our strategy, the allylic acetate in 3 is activated by the Pd(0) catalyst, resulting in a 5- exo-trig cyclization in the presence of a base with concomitant migration of the olefin to give 4 (Scheme , eq 2).…”

“… 15 Furthermore, a Tsuji–Trost allylation/retro-Claisen/Tsuji–Trost cyclization sequence was recently reported to afford a range of vinylcyclopropanes. 16 In our strategy, the allylic acetate in 3 is activated by the Pd(0) catalyst, resulting in a 5- exo-trig cyclization in the presence of a base with concomitant migration of the olefin to give 4 ( Scheme 1 , eq 2). Then, activation of the new allylic acetate moiety by Pd(0) should lead to 3- exo-trig cyclization, as 5- endo-trig cyclization is believed to be hampered by the E -geometry of the allylpalladium intermediate.…”

Cyclopropanation of Aryl and Styryl Acetonitriles With Selenium‐Based Dielectrophiles

“…[17] Few synthetic strategies affording vinylciclopropanecarbonitriles are disposable in the literature such as the anion relay cyclopropanation of vinyl epoxides and aldehydes. [18]…”