Ni‐Catalyzed [4+3+2] Cycloaddition of Ethyl Cyclopropylideneacetate and Dienynes: Scope and Mechanistic Insights

Abstract

A detailed study of the Ni-catalyzed [4+3+2] cycloaddition reaction between ethyl cyclopropylideneacetate and dienynes has been conducted, resulting in the development of a new method for the synthesis of compounds containing nine-membered rings. We studied the reactivity of various dienynes, together with their substituent and conformational effects. The mechanism of the reaction was probed by examining the stoichiometric reactions of the Ni complexes and dienynes.

Transition-Metal-Catalyzed Cycloadditions for the Synthesis of Eight-Membered Carbocycles: an Update from 2010 to 2020

“…[4＋2＋2] cycloadditions of enynes with dienes, [41] dienynes with alkynes, [39][40] trienes with alkynes [42] and diynes with dienes [43] have been reported. In 2013, Ogoshi, Sato, and coworkers [44] discovered the first case of [4＋2＋ 2] cycloaddition of dienyne 10-4 with methylenecyclopropane 10-5 (Scheme 10). In their study, nickel-catalyzed [4＋3＋2] cycloaddition of ethyl cyclopropylideneacetate 10-2 with dienyne 10-1 was achieved to form nine-membered carbocycle 10-3, and only in one case eight-membered ring compound was observed.…”

Preparation and Utility of N-Alkynyl Azoles in Synthesis

“…Saito reported a nickel-catalyzed [3 + 2 + 2] cycloaddition of ethyl-cyclopropylideneacetate and N -alkynyl pyrrole in 2010 (Scheme 70) [111]. The researchers were interested in the use of heteroatom-substituted alkynes as substrates in three-component cycloadditions to construct complex cycloheptadienes in one step.…”

Yb(OTf)3‐Catalyzed Cycloaddition/[3,3]‐Rearrangement of N‐Vinyl‐α,β‐Unsaturated Ketonitrones with Methylenecycloprop‐anes: Stereoselective Synthesis of Nine‐Membered Nitrogen Heterocycles

“…In particular, adding Cu (OTf) 2 afforded 3 aa in 50% yield with a 15:1 dr ( Table 1, entries 2-3). Other solvents, such as MeCN, DCM, and toluene delivered 3 aa in low yields but with excellent cis/trans ratios in DCM and toluene ( Table 1, entries [10][11][12]. Pleasingly, Yb(OTf) 3 and Sc (OTf) 3 delivered 3 aa in 78% and 69% yields, respectively, with a 15:1 cis/trans ratio (Table 1, entries 6-7).…”

“…[6] However, reports on the synthesis of nine-membered rings through cycloaddition, such as formal [6 + 3], [5 + 4], [4 + 4 + 1], and [4 + 3 + 2] reactions, are limited. [7][8][9][10] A few examples of excellent diastereoselectivity and enantioselectivity in the formation of nine-membered rings have been reported, however, the reaction efficiency and substrate scope remain to be explored, particularly when multiple stereocenters are present owing to difficulty in controlling the large ring transition state.…”