Gold(I)-catalyzed synthesis of γ-vinylbutyrolactones by intramolecular oxaallylic alkylation with alcohols

Abstract

SummaryGold(I)-N-heterocyclic carbene (NHC) complexes proved to be a reliable catalytic system for the direct synthesis of functionalized γ-vinylbutyrolactones by intramolecular oxaallylic alkylation with primary alcohols. Good isolated chemical yields were obtained for a range of malonyl and acetate derivatives. The good performance in reagent-grade solvents and the functional group/moisture tolerance make this catalytic process a promising route for the synthesis of architecturally complex polycyclic structures.

Debenzylative Cycloetherification: An Overlooked Key Strategy for Complex Tetrahydrofuran Synthesis

“…One year thereafter, a similar protocol was reported by Bandini and co‐workers for the synthesis of a range of functionalized malonyl esters by direct activation of allylic alcohols, instead of allylic acetates as previously described, in the presence of a gold(I) N ‐heterocyclic carbene (NHC) complex as a catalyst . When benzyl ester 167 was subjected to the reaction conditions (IMesAuCl/AgOTf, DCE, 80 °C), the corresponding lactone 169 was isolated in 67 % yield and in 1.4:1 as a trans / cis ratio (Scheme ).…”

A Review of the Pharmacological Activities and Recent Synthetic Advances of γ-Butyrolactones

“…Gold-catalyzed allylic functionalization has been the object of diverse cyclization reactions and has been found to be efficient for the preparation of γ-butyrolactone [90][91][92]. Chen and colleagues examined the Au-catalyzed lactonization of allylic acetate 29 to construct a butyrolactone system ( Figure 11 Bandini and colleagues reported the direct activation of free allylic alcohol 32 by applying a gold catalyst with N-heterocyclic carbene ( Figure 12) [94]. An allylic cation intermediate is generated upon coordination of the NHC-gold complexes to a free allylic alcohol 32.…”

“…The resulting poly-substituted γ-butyrolactone 33 was obtained via nucleophilic attack by ester and subsequent dealkylation. Bandini and colleagues reported the direct activation of free allylic alcohol 32 by a plying a gold catalyst with N-heterocyclic carbene ( Figure 12) [94]. An allylic cation inte mediate is generated upon coordination of the NHC-gold complexes to a free allylic alc hol 32.…”

Gold‐Catalyzed Allylation Reactions

“…Later, Bandini and co‐workers successfully exploited this methodology for the preparation of a library of densely functionalized γ‐vinylbutyrolactones by means of an intramolecular dealkoxylative oxa‐allylic reaction. Au(IMes)Cl/AgOTf (5 mol %, IMes=1,3‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene) proved competent for this reaction, but modest diastereoselectivity was obtained …”

“…Au(IMes)Cl/AgOTf( 5mol %, IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene) proved competent for this reaction, but modest diastereoselectivity was obtained. [21] Researcht owards the control of the stereochemical profile (i.e.,e nantioselection) of the reaction has been performedb y severalg roups.I np articular, the enantioselective synthesis of vinyl morpholines (16)a nd seven-membered-ring analogues was recorded, by reacting readily availablem onoallyl diols 15 in the presence of DTBM-segphos(AuCl) 2 /AgNTf 2 . [22] Primary,a s well as tertiary, alcohols workeds moothly as nucleophilic partners and the stereochemical course was drastically impacted by the configuration of the C=Cb ond of the allylic unit (Scheme 7a).…”