4,5‐Bis(furoylsulfanyl)‐1,3‐dithiole‐2‐thione

The title compound, C₁₃H₆O₄S₅, possesses crystallographically imposed mirror symmetry, with the atoms of the C=S group lying on the mirror plane. It is an example of the general formula [RCO]₂(dmit), where R is a furan ring and dmit is 2‐thioxo‐1,3‐dithiole‐4,5‐dithiol­ate. The components exhibit some polarization of their mol­ecular–electronic structure. The dmit and furan moieties exhibit a high degree of conjugation, as the introduction of C=O connecting the conjugated furan (donor) and dmit (acceptor) rings forms a good conjugated system with high delocalization. A polar three‐dimensional framework is built from a combination of inter­molecular contacts, namely S⋯S inter­actions and C—H⋯O hydrogen bonding. The structural characteristics lead to good second‐order non‐linear optical properties.     

2‐Pyrazolines from 1,3 ‐ dipolar cycloaddition of diazomethane to arylsulfonylethenes

Novel 2‐pyrazolines were obtained by the cycloaddition of diazomethane to bis(arylsulfonylethenyl)‐sulfones ( 3 ) and 1‐arylsulfonyl‐2‐styrylsulfonylethenes (7). Dehydrogenation of 2‐pyrazolines with chloranil gave pyrazoles.     

Nitropyridyl isocyanates in 1,3‐dipolar cycloaddition reactions

The reactivity of 3‐nitro‐4‐pyridyl isocyanate ( 7 ) and 5‐nitropyridin‐2‐yl isocyanate ( 9 ) in 1,3‐dipolar cycloaddition reactions with azides and pyridine N‐oxides has been investigated. 1,3‐Dipolar cycloaddition to trimethylsilylazide (TMSA) afforded the respective tetrazolinones, 1‐(3‐nitropyridin‐4‐yl)‐1H‐tetrazol‐5(4H)one ( 8 , 50 %) and 1‐(5‐nitropyridin‐2‐yl)‐1H‐tetrazol‐5(4H)one ( 11 , 64 %). Respectively, 1,3‐dipolar cycloaddition of nitropyridyl isocyanates 7 and 9 to 3,5‐dimethylpyridine N‐oxide ( 14 ), 3‐methylpyridine N‐oxide ( 21 ) and pyridine N‐oxide ( 22 ) gave the substituted amines, 3,5‐dimethyl‐N‐(3‐nitropyridin‐4‐yl)pyridin‐2‐amine ( 17 ), 3,5‐dimethyl‐N‐(5‐nitropyridin‐2‐yl)pyridin‐2‐amine ( 20 ), N‐(5‐nitropyridin‐2‐yl)pyridin‐2‐amine ( 24 ), 5‐methyl‐N‐(5‐nitropyridin‐2‐yl)pyridin‐2‐amine ( 23 ) and 3‐methyl‐N‐(5‐nitropyridin‐2‐yl)pyridin‐2‐amine ( 25 ) in 65 ‐ 80 % yield, obtained by cycloaddition, rearrangement and decarboxylation. The results demonstrate that the nitropyridyl isocyanates ( 7,9 ) readily undergo 1,3‐dipolar cyloaddition reactions similar to phenyl isocyanates.     

Reactivity of 2‐methylene‐1,3‐dicarbonyl compounds. 1,3‐dipolar cycloaddition reaction with nitrile oxide

The reaction of 2‐methylene‐1,3‐dicarbonyl compounds 1 and nitrile oxides, which were prepared from hydroxymoyl chlorides 2 with triethylamine, gave 5,5‐disubstituted 2‐isoxazolines 3 regioselectively.     

A regioselective 1,3‐dipolar cycloaddition of 2‐arylidene‐1‐tetralones with DPNI

Synthesis of a series of novel 1,3‐diphe nyl‐4‐arylspiropyrazolines[5.2¹]‐1¹‐tetralones has been accomplished in good yield by regioselective 1,3‐dipolar cycloaddition of diphenylnitrilimine with (E)‐2‐arylidene‐1‐tetralones. X‐ray crystal structure analysis of one of the products 4b confirms the structure and the regiochemistry of cycloaddition. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 331–336, 1999     

Tetraphenylphosphonium bis(2‐thioxo‐1,3‐dithiole‐4,5‐dithiolato)aurate(III) acetone solvate and ethyltriphenylphosphonium bis(2‐thioxo‐1,3‐dithiole‐4,5‐dithiolato)aurate(III)

In the two title complexes, (C₂₄H₂₀P)[Au(C₃S₅)₂]·C₃H₆O, (I), and (C₂₀H₂₀P)[Au(C₃S₅)₂], (II), the Au^III atoms exhibit square‐planar coordinations involving four S atoms from two 2‐thioxo‐1,3‐dithiole‐4,5‐dithiolate (dmit) ligands. The Au—S bond lengths, ranging from 2.3057 (8) to 2.3233 (7) Å in (I) and from 2.3119 (8) to 2.3291 (10) Å in (II), are slightly smaller than the sum of the single‐bond covalent radii. In (I), there are two halves of independent Ph₄P⁺ cations, in which the two P atoms lie on twofold rotation axis sites. The Ph₄P⁺ cations and [Au(C₃S₅)₂]⁻ anions are interspersed as columns in the packing. Layers composed of Ph₄P⁺ and [Au(C₃S₅)₂]⁻ are separated by layers of acetone molecules. In (II), the [Au(C₃S₅)₂]⁻ anions and EtPh₃P⁺ counter‐cations form a layered arrangement, and the [Au(C₃S₅)₂]⁻ anions form discrete pairs with a long intermolecular Au...S interaction for each Au atom in the crystal structure.     

N‐Ethylpyridinium bis(2‐thioxo‐1,3‐dithiole‐4,5‐dithiolato)nickelate

The title compound, (C₇H₁₀N)[Ni(C₃S₅)₂] or (Etpy)[Ni(dmit)₂] (where Etpy is the N‐ethyl­pyridinium cation, C₇H₁₀N⁺, and dmit is the 2‐thio­xo‐1,3‐di­thiole‐4,5‐di­thiol­ate dianion, C₃S₅²⁻), crystallizes in the P space group with two mol­ecules in the asymmetric unit. The [Ni(dmit)₂]⁻ monoanion has a planar D_2h conformation, with the central Ni atom and the four coordinated S atoms forming an NiS₄ square plane. The six‐membered ring of the Etpy cation also shows good planarity, as expected. There are two main types of disorder in the two Etpy cations. Several short intermolecular interactions are present, such as S⋯S, Ni⋯S and Ni⋯Ni, which help to form the enhanced three‐dimensional structure of the crystal.     

Enantioselective 1,3‐dipolar cycloaddition reactions using chiral lanthanide catalysts

Regio‐ and stereoselective 1,3‐dipolar cycloaddition of nitrile oxides to internal 2‐pentenols, α,β‐unsaturated esters and amides catalyzed by R‐(+) BINOL‐lanthanide complexes affords corresponding 3‐aryl‐2‐isoxazolines with enantioselectivities up to 89% ee.     

A nonconcerted cycloaddition of fused 2-vinylthiophenes with dimethyl acetylenedicarboxylate

Fused thiopyrans along with products of subsequent reactions of the primary adducts of the title compounds are obtained by nonconcerted [4π + 2π] processes. The course of the reactions and formation of all products discussed.     

Preparation of 4,5‐dihydro‐1,3‐selenazoles by reaction of aromatic primary selenoamides with acetylenedicarboxylate

Reactions of primary selenoamides with dimethyl acetylenedicarboxylate afforded 2‐aryl‐5‐methoxy‐carbonylmethylene‐4,5‐dihydro‐1,3‐selenazol‐4‐ones in moderate to high yields. Reactions of the primary selenoamides with acetylenedicarboxylic acid gave 2‐aryl‐5‐carboxymethylene‐4‐ethoxy‐4,5‐dihydro‐1,3‐selenazol‐4‐ols in moderate yields.     

1,3‐dipolar cycloaddition reactions of nitrile oxides to prop‐1‐ene‐1,3‐sultone

The reaction of prop‐1‐ene‐1,3‐sultone 1 with a variety of nitrile oxides 3 afforded novel [3+2] cycloaddition products 4 in good yield. The cycloaddition reaction achieved excellent regioselectivity.     

Rh-catalyzed intermolecular and enantioselective [4 + 2] cycloaddition of 1,3-dienes with dimethyl acetylenedicarboxylate

A Rh-BINAP complex catalyzed an intermolecular and enantioselective [4 + 2] cycloaddition of 1-monosubstituted, 1,1- or 1,2-disubstituted buta-1,3-dienes with dimethyl acetylenedicarboxylate to give chiral cyclohexa-1,4-dienes.     

Enantioselective 1,3‐dipolar cycloaddition reactions using complexes of (−)‐sparteine

Regio‐ and stereoselective 1,3‐dipolar cycloaddition of nitrile oxides to internal 2‐pentenols and α,β‐unsaturated esters catalyzed by (?) sparteine‐lanthanide complexes affords corresponding 3‐aryl‐2‐isoxazolines with enantioselectivities up to 68% ee.     

Regioselective synthesis of novel spiroheterocyclic framework via the 1,3‐dipolar cycloaddition

A series of novel dispiro[oxindole‐fused pyrimidine]pyrrolidine ring systems 4a‐f were synthesized by the regioselective 1,3‐dipolar cycloaddition reaction of the 2‐arylmethylene‐7‐benzyl‐9‐(benzylidene)tetrahydropyrido[4,3‐d]thiazolo[3,2‐a]pyrimidin‐3‐ones 1a‐f with azomethine ylides, generating by the decarboxylative route from isatin 2 and sarcosine 3 , in moderate to good yields. The regiochemistry of designed dispiroheterocyclic compounds 4a‐f was established by single crystal X‐ray structure and spectroscopic techniques.     

Synthesis of potentially photoactivatable coumarin derivatives via a 1,3‐dipolar cycloaddition

A copper (1)‐catalyzed 1,3‐dipolar cycloaddition reaction was used to prepare a series of mono and disubstituted 1,2,3‐triazolyl‐coumarins using a 1,3‐cycloaddition (“Click Chemistry”). Starting coumarins were synthesized using classical or modified Pechmann's reaction. The propargyl group was introduced as either propargylether or as a propargylamide. Azides were prepared in a three steps procedure. Cycloaddition products, containing a coumarin and a photoactivatable moiety, were obtained in good yields.     

Diphenyl(2‐thioxo‐1,3‐dithiole‐4,5‐di­thiolato‐S,S′)plumbane at 295 K and diphenyl(2‐thioxo‐1,3‐dithiole‐4,5‐di­thiolato‐S,S′)stannane at 150 K

Molecules of di­phenyl(2‐thio­xo‐1,3‐di­thiole‐4,5‐di­thiol­ato‐S,S′)­plumbane, [Pb(C₃S₅)(C₆H₅)₂], are linked into sheets via two intermolecular Pb?S_thione interactions of 3.322 (4) and 3.827 (4) Å; the Pb centre has a distorted octahedral geometry. In contrast, mol­ecules of ­di­phenyl(2‐thio­xo‐1,3‐di­thiole‐4,5‐di­thiol­ato‐S,S′)­stannane, [Sn(C₃S₅)(C₆H₅)₂], are linked into chains via a single intermolecular Sn—S_thione interaction of 2.8174 (9) Å; the Sn centre has a distorted trigonal‐bipy­ramidal geometry.     

Kinetics of 1,3‐dipolar cycloaddition reaction between C,N‐diphenylnitrone and dimethyl fumarate in various solvents and aqueous solutions

Second‐order rate constants and activation parameters of 1,3‐dipolar cycloaddition reaction between C,N‐diphenylnitrone and dimethyl fumarate were obtained in various solvents and aqueous solutions at 65°C. Second‐order rate constants of the reaction in water and ethylene glycol are approximately 33 and 8 times faster than those expected from solvent polarity, respectively. Increase of the reaction rate in aqueous solutions of ethanol is higher than that of propan‐1‐ol. A multiparameter correlation of log k₂ vs Sp and E_T^N in various solvents and aqueous solutions of ethanol shows that solvophobicity and solvent polarity parameter are important factors in occurrence of the reaction. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 431–434, 2000