Gold(III)‐ and Platinum(II)‐Catalyzed Domino Reaction Consisting of Heterocyclization and 1,2‐Migration: Efficient Synthesis of Highly Substituted 3(2H)‐Furanones

Abstract

PtCl2‐catalyzed alkyne activation initiates a domino reaction, in which a heterocyclization is followed by a 1,2‐alkyl migration, for the construction of a variety of substituted 3(2H)‐furanones. This stereospecific reaction is proposed to proceed through an oxonium ion intermediate (see scheme).

A facile base-promoted domino Michael/O-alkylation reaction for the construction of succinimide-substituted 3(2H)-furanones

“…Under the optimal reaction conditions, the generality of this protocol was studied (Table 3). Firstly, a wide range of maleimides 1a-n was studied (Table 3, entries [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The maleimides included those bearing electronwithdrawing and electron-donating substituents on the aryl ring, as well as N-alkyl maleimides.…”

“…[1][2][3][4] The significance of these molecules has led to a variety of approaches for the synthesis of substituted 3(2H)-furanones, including acid-catalyzed cyclization-dehydration, 5,6 transformations from furans, 7,8 alkynes [9][10][11][12][13][14][15] and allenes. 16 However, most of these routes require the use of specific substrates and reaction conditions are often harsh.…”

Gold in Homogeneous Catalysis

“…79 The reaction proceeds by carbonyl attack to the enyne and pinacol-type rearrangement, where a 1,2-migration of the propargylic substituent takes place. When R 1 and R 2 are part of a ring, this rearrangement leads to a ring contraction.…”

Catalytic Regioselective Control in the Diastereoselective 1,3‐Dipolar Cycloaddition Reactions of 1‐(1‐Alkynyl)cyclopropyl Ketones with Nitrones

“…The major diastereomer may be formed from the more favorable chair-like conformation of intermediate B. In contrast, the cationic gold(I) species preferentially binds to the alkyne, [14] rather than the carbonyl, and, thus, mediates nucleophilic attack to give oxonium-containing vinyl-gold intermediate C (cycle 2). This is followed by the regioselective homo-Michael addition of nitrone 2 at the more substituted position of the cyclopropyl ring, [6, 2a, 15] which produces furanyl-gold intermediate D; in turn, this, upon ring closure, gives the formal [4+3] cycloadduct and regenerates the gold catalyst.…”