Thermolysis complexes

Thiirane is more bactericidal than oxirane, and derivatives of 2-mei captomethylthiirane inhibit tuberculosis. The following pharmacological uses have been reported for compounds derived from thiirane derivatives gold complexes of the adducts of diethylphosphine and thiirane (antiarthritic), adducts of thiiranes and malononitrile (antibacterial, blood vessel dilators, muscle relaxants, sedatives), thermolysis products of thiirane 1-oxides and adducts of thiirane 1-oxides with sulfenyl chlorides (antibacterial), adducts of 2,3-diarylthiirene 1,1-dioxides with ynamines (antibacterial, parasiticidal), adducts of 2,3-diarylthiirene 1,1-dioxides with enamines (antifertility), adducts of p-aminophenylacetic esters with thiirane (immunosuppressants), adducts of amines and thiiranes (radioprotective drugs). 

Thermolysis of the t]-coordinated zirconium complex of thiophene Cp2Zr(SiMc3) (C4H3S) is a thienyl ring cleavage reaction (920M1646). 

The rhodium and iridium complexes of dibenzothiophene (L) reveal an interesting case of linkage isomerism (91IC5046). Thus, the ti S) coordinated species [MCp LCb] on thermolysis with silver tetrafluoroborate afford the Ti -coordinated dicationic species. 

With [RUjfCOlij], dinuclear species 161 emerges (88JCS(D)1437). In contrast, with [Os3(CO) q(AN)J, two isomers, 162 and 163, result (88JOM (353)251). Isomer 162 enters the CO/AN monosubstitution reaction in acetonitrile in the presence of Mc3N0-2H20, the product on subsequent thermolysis forms the hexanuclear complex 164. 

Dimethyl-1,2,4-triazolium iodide with palladium acetate yields the carbene adduct 182 (97JOM(530)259). Under water it undergoes cis-trans isomerization to 183. Some other derivatives were reported in 1981 (81BCSJ800). 1,1 -Methylenebis(4-alkyl-l,2,4-triazolium)diiodides (alkyl = /-Pr, n-Bu, octyl) with palladium(II) acetate give the mononuclear complexes [L Pdl ] (99EJIC1965), where L2= l,l -methylenebis(4-R-l,2,4-triazol-2-ylidene) (R = /-Pr, n-Bu, octyl). Thermolysis of the products in THF gives the rran -dinuclear complexes 184... 

Complex [(r] (N)-2,1,3-benzothiazole)Os(CH=CHTol-p)(CO)Cl(PPh3)2] with potassium hydrotris(pyrazol-l-yl)borate at the first stage gives the >7 -coordinated [(>7 -Tp)Os(CH=CHTol-p)(CO)Cl(PPh3)2], which eliminates triphenylphosphine on thermolysis and gives the > -coordinated [(> -Tp)Os(CH=CHTol-p)(CO)Cl (PPh3)l [98JCS(D)3501]. 

The Chugaev elimination is of synthetic value, because it proceeds without rearrangement of the carbon skeleton. Other non-thermolytic elimination procedures often lead to rearranged products, when applied to the same substrates. However applicability of the Chugaev reaction is limited if the elimination is possible in more than one direction, and if a /3-carbon has more than one hydrogen. Complex mixtures of isomeric olefins may then be obtained. For example the thermolysis of xanthate 12, derived from 3-hexanol yields 28% S-hex-3-ene 13, 13% Z-hex-3-ene 14, 29% -hex-2-ene 15 and 13% Z-hex-2-ene 16 ... 

Attempts have been made to catalyze the arrangement of 3-oxaquadricyclane to oxepins with transition-metal complexes.1 32 1 35 When dimethyl 2,4-dimethyl-3-oxaquadricyclane-l,5-dicarboxylate is treated with bis(benzonitrile)dichloroplatinum(II) or dicarbonylrhodium chloride dimer, an oxepin with a substitution pattern different from that following thermolysis is obtained as the main product. Instead of dimethyl 2,7-dimethyloxepin-4,5-dicarboxylate, the product of the thermal isomerization, dimethyl 2,5-dimethyloxepin-3,4-dicarboxylate (12), is formed due to the cleavage of a C O bond. This transition metal catalyzed cleavage accounts also for the formation of a 6-hydroxyfulvene [(cyclopentadienylidene)methanol] derivative (10-15%) and a substituted phenol (2-6%) as minor products.135 The proportion of reaction products is dependent on solvent, catalyst, and temperature. 

The yield of 3//-azepine appears to be influenced by substituents on the azide ring although no in-depth study has been reported. 4-Halophenyl azides, in most cases, give rise to complex mixtures of products.177 4-Tolyl azide, on thermolysis in aniline, yields 5-methyl-iV-phenyl-3//-azepin-2-amine (18% mp 157-158°C), whereas the thermolyses of 4-methoxy-, 4-methyl-, 4-chloro-, and 4-nitrophenyl azides in a range of arylamines (4-chloro-, 4-methoxy-, and pen-tafluoroaniline) yield only azo compounds and uncharacterized tarry products.178... 

Thermolysis of the azide 15, bearing an allyl side chain, is more complex, and in addition to ethyl 4-allylindole-2-carboxylate and ethyl 4-methyl-l//-3-benzazepine-2-carboxylate (16 oil), two unstable tricyclic aziridines 17 and 18 are produced.82 A mechanistic rationale for these results has been suggested. 

The formation of 2-(t-butyl)-2-trimethylsilyl-2//-thiopyran has recently been reported from 1-substituted 1,3-butadienes with /-BuCSSiMe3 (92MI1) (see Scheme 2). An unusual product with proposed structure 47b has been reported (84JOC5143) from benzothiopyrone 46 on reaction with sec-butyl lithium (46 - 47a — 47b, Scheme 3) on the basis of spectroscopic data. 6-Methylthio-2//-thiopyran was isolated after the flash vacuum thermolysis of more complex starting precursors (93TL2605). 

Thermolysis of m-PtH(CH2CMe3)(cy2PC2H2Pcy2) at 45-80°C yields a bent platinum(0) complex (Figure 3.13) that is intensely reactive to a whole range of unactivated C—H bonds in saturated and unsaturated hydrocarbons. 

---