A New Type of Highly Polar 1,3-Dipoles. Synthesis and Chemistry of Thiocarbonyl-stabilized Pyrazolidinazomethineimies
摘要:
3-Thioxopyrazolidine-azomethineimines (2) are synthesized from their 3-oxo analogues (1) and Lawesson's reagent (LR). The electron structures of 1 and 2 resemble those of polymethines, dipole moments of 2 are even higher than those of 1; further physical organic data are discussed. With NaBH4 2 gives 3-thioxopyrazolidines (8). These are S-mono- (10) and (N-1), S-bisalkylated (11). S-Alkylation of 2 affords pyrazolinium salts (7). 1,3-Dipolar cycloaddition of enamines to 2 results in [pi4s +pi2s] products (12, 13), HOMO/LUMO energies of 1 and 2 are given. Models of gamma-thiolactams (17, 19), mimicing antibiotics, are gained via 1,3-dipolar cycloadducts of 1 with LR.
Catalyst-Free and Stereoselective Synthesis of N,N-Bicyclic Pyrazolidinone Derivatives
摘要:
A catalyst-free and stereoselective cycloaddition of pyrazolidin-3-one-derived azomethine imine to trans-beta-nitrostyrene is described, which allows versatile, efficient and highly enantioselective synthesis of N,N-bicyclic pyrazolidinone derivatives.
Are any non-stereospecific 1,3-dipolar cycloadditions known? A revision
作者:Rolf Huisgen、Rudolf Weinberger
DOI:10.1016/s0040-4039(00)98877-4
日期:1985.1
The cycloaddition of 1-benzylidenepyrazolid-3-one betaine to (E)-β-nitrostyrene, which has been claimed to furnish 15–30% non-stereospecific product, revealed stereospecificity up to 99.92% in a renewed study; (Z)-β-nitrostyrene stereoisomerizes under the influence of the 1,3-dipole.