Amine-functionalized MCM-41 as an efficient catalyst for the synthesis of sulfur/dinitrogen-fused heterocycles via [3+3] cycloaddition in water

Abstract

The sulfur/dinitrogen-containing heterocycle is an important chemical motif and is found widely in natural products, drug molecules, catalysts and functional materials. Here we report an efficient recoverable amine functionalized mesoporous...

(4 + 3) Cycloaddition Reaction of Sulfonylphthalide with N,N′-Cyclic Azomethine Imines: Synthesis of Pyrimidinone-Fused Naphthoquinones

“…6 Recently, Zhang and Chen reported an MCM-41-NH 2 -catalyzed [3 + 3] cycloaddition between azomethine imines and 1,4-dioxane-2,5-dithiol in water for the synthesis of sulfur/dinitrogen-fused heterocycles (Scheme 1, eq 5). 7 Up to now, the chemistry of N,N′-cyclic azomethine imines has been limited to the preparation of dinitrogen-fused heterocycles only; that is, the pyrazolidin-3-one skeleton is ubiquitously present in the products. We envision that the development of a strategy for the generation of new molecular scaffolds other than the pyrazolidin-3-one moiety may broaden N,N′-cyclic azomethine imine's application toward the synthesis of structurally diverse heterocycles.…”

“…Shi et al reported a Brønsted acid-catalyzed [4 + 3] cyclization of azomethine imines with isatoic anhydrides to the preparation of seven-membered nitrogenous heterocycles (Scheme , eq 4) . Recently, Zhang and Chen reported an MCM-41-NH 2 -catalyzed [3 + 3] cycloaddition between azomethine imines and 1,4-dioxane-2,5-dithiol in water for the synthesis of sulfur/dinitrogen-fused heterocycles (Scheme , eq 5) . Up to now, the chemistry of N,N ′-cyclic azomethine imines has been limited to the preparation of dinitrogen-fused heterocycles only; that is, the pyrazolidin-3-one skeleton is ubiquitously present in the products.…”

“…Here, we report an unexpected rearrangement of [4 + 3] cycloaddition adducts from the reaction of sulfonylphthalides with N,N′-cyclic azomethine imines under basic conditions. The adducts are characterized as isomerized pyrimidinone-fused naphthoquinones instead of the predicted pyrazolidinone-fused benzo [7]annulenediones. The substrate scope of this reaction is investigated, and a possible mechanism for this isomerization reaction is proposed.…”

“…To our surprise, the expected [4 + 3] cyclization product 3a′ was not observed. Instead, pyrimidinone-fused naphthoquinone 3a was generated in 57% yield, apparently from the rearrangement of pyrazolidinone-fused benzo [7]annulenedione 3a′. The molecular structure of 3a was confirmed by the X-ray crystallography, as shown in Figure 2.…”

“…The scope of this reaction was demonstrated by the preparation of 19 pyrimidinone-fused naphthoquinones (3a−3s). The mechanism presumably involves the first formation of pyrazolidinone-fused benzo [7]annulenedione adduct 3a′ and is followed by N−N bond cleavage to the rearranged pyrimidinone-fused naphthoquinone 3a. The prepared compounds 3 can be facilely converted to the isoquinoline-1,4-dione derivatives 5a− 5e under the influence of Cs 2 CO 3 in methanol or ethanol.…”