Gold-Catalyzed Diastereoselective Formal Intermolecular [4 + 2 + 1] Cycloaddition of 1,3-Dien-8-yne with Diazo Ester

Abstract

The first example of gold-catalyzed formal intermolecular [4 + 2 + 1] cycloaddition was developed using 1,3-dien-8yne as C4 and C2 units and diazo ester as the C1 unit, which provides expedient access to a series of structurally complicated [5.3.0] bicyclic adducts in moderate yields with moderate to high diastereoselectivities. The key route involved a cascade process of dienyne cycloisomerization, cyclopropyl gold carbene's trapping, and subsequent divinyl cyclopropane (DVCP) Cope rearrangement.

Assembly of Complex 1,4‐Cycloheptadienes by (4+3) Cycloaddition of Rhodium(II) and Gold(I) Non‐Acceptor Carbenes

“…Vinylcarbenes arising from the gold(I)‐catalyzed isomerization 5‐alkoxy‐1,6‐enynes 6 also undergo similar (4+3) cycloadditions (Table 2). Hydroazulenes 7 were obtained in one step, in a stereoselective manner, bearing the common core of the daucene family of natural products [23, 24] . We found that the selectivity between the formation of cycloheptadiene 7 or cyclopropane 8 is dependant on the sterics and electronics of the catalyst [25] .…”

Small rings in the bigger picture: ring expansion of three- and four-membered rings to access larger all-carbon cyclic systems

“…Another approach starting also from dienyne, was reported by Chen. 108 The authors set an elegant formal gold mediated (4+2+1) cycloaddition reaction to access [5.3.0] substituted bicyclic compounds. The intermolecular reaction between dienyne 145 and a donor-acceptor diazo compound 146 in presence of a NHC-Au(I) catalyst, provided adduct 147 in very good yields (Scheme 46).…”

Assembly of Complex 1,4‐Cycloheptadienes by (4+3) Cycloaddition of Rhodium(II) and Gold(I) Non‐Acceptor Carbenes

“…Hydroazulenes 7 were obtained in one step,i nastereoselective manner, bearing the common core of the daucene family of natural products. [23,24] We found that the selectivity between the formation of cycloheptadiene 7 or cyclopropane 8 is dependant on the sterics and electronics of the catalyst. [25] Catalyst A provided the highest selectivity towards the formation of cyclopropane 8a (Table 2, entry 1: 1:2 7a/8a), while bulkier B gave a1:1 ratio of 7a/8a (Table 2, entry 2).…”