The Catalytic Asymmetric 1,3-Dipolar Cycloaddition of Ynones with Azomethine Ylides

Abstract

The first catalytic asymmetric 1,3-dipolar cycloaddition of electron-deficient carbon-carbon triple bonds with azomethine ylides has been established. This reaction provides an unprecedented approach to access novel 2,5-dihydropyrrole derivatives with potential bioactivities in perfect enantioselectivities of up to >99% ee.

Organocatalytic transformations of alkynals, alkynones, propriolates, and related electron-deficient alkynes

“…132 In most cases, the 2,5-dihydropyrroles 268 were obtained in good yields and high enantiomeric excess. The scope was broad both for the aldehyde 133 Unfortunately, with a-arylglycine esters (R 3 ¼Ar, 267) they observed poor diastereoselectivities.…”

Peculiarities of the cascade cleavage of the polarized C≡C-fragment in α-ketoacetylenes on reaction with ethylene diamine

“…A mixture of Pd(Ph 3 P) 2 Cl 2 (65 mg, 0.093 mmol) and CuI (40 mg, 0.211 mmol) in THF (20 mL) was stirred in the argon atmosphere for 10 min. Then triethylamine (5 mL), 3,4,5-trimethoxybenzoyl chloride (1) (1.15 g, 5 mmol) and 1,5-dimethyl-4-ethynylpyrazole (2b) (0.60 g, 5 mmol) were added successively.…”

“…α-Ketoacetylenes possess additional synthetic potential: 2,3 Owing to the increased electrophilicity of the acetylenic fragment and its proximity to the carbonyl group, these compounds represent excellent models for studying the factors controlling regioselectivity of their addition reactions. In the reactions with nucleophilic reagents, such structures are prone to facile heterocyclization.…”

Synthesis of 2,3,4,5-tetrasubstituted pyrroles and 1,4-dihydro-tetraarylpyrazines using acidic alumina as a heterogeneous catalyst

“…In addition, pyrroles have also been synthesized by the Huisgen reaction [20][21][22], cyclization of N-propargylic derivatives [23,24], including propargyl aziridines [25,26], through the cyclocondensation of vinyl azides with 1,3-dicarbonyls [27,28], transition-metal-catalyzed cyclization [29], [3 + 2] cycloadditions [30], and multi-component reactions [4,[31][32][33][34][35][36][37][38][39], among various other alternatives. Nevertheless, some of these methods need multiple steps, expensive or prefunctionalized substrates, and using reagents which generate halide wastes.…”