A Au(I)-Catalyzed Alkoxylation-Induced Double Aldol Condensation Approach to 2,2'-Spirobi[indene] Derivatives

Abstract

An efficient gold(I)-catalyzed intramolecular alkoxylation/double aldol condensation cascade cyclization strategy to synthesize 2,2'-spirobi[indene] derivatives has been developed. The scope of this strategy was examined by using a batch of synthetic alkynone substrates and a possible mechanism was proposed.

Gold(I)-Catalyzed Tandem Intramolecular Methoxylation/Double Aldol Condensation Strategy Yielding 2,2′-Spirobi[indene] Derivatives

“…5 Herein, a gold(I)-catalyzed tandem intramolecular methoxylation/double aldol condensation strategy for synthesizing 2,2′-spirobi[indene] scaffold was reported (Scheme 1, e). 6 In our previous research on synthesizing heterocycles, it was discovered that a gold(I)-catalyzed cycloisomerization via alkoxylation of alkyne/nucleophilic addition furnished indanones, which could act as versatile intermediates to access structurally diverse skeletons (Figure 1). When there was a nucleophilic substituent on the benzene ring (e.g., X = OH), a sequential intramolecular Michael addition reaction occurred to provide indenochromen-4-one derivatives (Figure 1, path a).…”

“…The novel reactivities and reaction modes of the gold catalysts with alkynes have inspired much elegant pioneering work to synthesize significant molecules, e.g., natural products and heterocycles . Herein, a gold­(I)-catalyzed tandem intramolecular methoxylation/double aldol condensation strategy for synthesizing 2,2′-spirobi­[indene] scaffold was reported (Scheme , e) …”