Flash vacuum pyrolysis(FVP) of azidomethylthiophene,via a nitrene intermediate,gave two products,a dimer (thienylmethylidene-thienylamine) and a trimer (N,N`-dithienyl methylidene-thienylmethylidene diamine).The trimer underwent cyclization and dehydrogenation to afford 2,4,5-trithienylimidazole. However by the same route, FVP of azidomethylbenzo[b]furan produced only a trimer(dibenzo[b]furylmethylidene-N,N'-benzo[b]furylmethyl amine).

(1) The pyrolysis of benzoic 5-benzyl-2-furoic anhydride by using SS-FVP method can obtain the ring-opened product naphthalene, and no ring-contracted product and its further derivatives. (2) Flash vacuum pyrolysis (FVP) of 2-(2-azidoethyl)thiophene, via a nitrene intermediate gave 1,2-di(2-thienyl)ethane, 3,5-di(2-thienyl)pyridine, and 2-methylthiophene as the main products.

(1) Flash vacuum pyrolysis (FVP) of (5-methyl-2-selenophenyl)methyl benzoate gave 4-methylene-4H-selenopyran. The structure was confirmed by trapping experiment. The mechanism for the 4-methylene-4H-selenopyran will be discussed. (2) Flash vacuum pyrolysis of 2-Azidomethylselenophene, via a nitrene intermediate, gave a trimer (N,N¡¦-di-2-selenophenylmethylidene-2-selenophenylmethylidene diamine).

Flash vacuum pyrolysis (FVP) of 2-azidoacetophenone gave the dimer 2-benzoyl-4- phenylimidazole and the trimer: 2,3-dibenzoyl-5-phenylpyrazine. Flash vacuum pyrolysis of 2-azido-1-(2-thienyl)ethanone gave the dimer: 2-(2-fromylthienyl)-4-(2-thienyl)imidazole and 2-formylthiophene.

Flash vacuum pyrolysis (FVP) of 2-azido-1-(1-methyl-2-pyrryl)ethanone and 2-azido-1- (2-benzo[b]thienyl)ethanone gave nitrene by elimination of one nitrogen molecule. When 2-azido-1-(1-methyl-2-pyrryl)ethanone as a precorsor, the reactive nitrene readily underwent self-condensation to give 2-(1-methyl-2-formylpyrryl)-4-(1-methyl-2- pyrryl)imidazole, it¡¦s isomer and 2,4,5-tri(1-methyl-2-formylpyrryl) imidazole. While 2-azido-1-(2-benzo[b]thienyl)ethanone as a precorsor, the reactive nitrene readily underwent self-condensation to give 2-2-formylbenzo[b]thienyl-5-(2-benzo[b]thiophen-2-yl)imidazole. The mechanism for the formation of products of self-condensation reaction from FVP of 2-azido-1-(1-methyl-2-pyrryl)ethanone and 2-azido-1-(2-benzo[b]thienyl) ethanone will be discussed.

Abstract¡G ¤@¡B trans o-Thiomethoxystilbene and its derivatives 19a-c had been studied by means of pyrolysis and photolysis. Under pyrolytic conditions, compounds 19a-c gave not only the products 24¡B30¡B33,but also their corresponding isomers 26¡B31¡B34 . Furthermore, compound 19c gave dibenzothiophene (32) as the major product by opening the furan ring at higher temperature. Under photolytic conditions, compounds 19a-c gave the corresponding photocyclic products 40¡B44¡B46. With the exception of 19c, photolysis of 19a and 19b also gave 24 and 30, respectively. ¤G¡B For synthetic study of thieno-fused derivatives 4 and 5 of truxene, preparation monomer 6 and 7 can be accomplished in two steps by means of flash vacuum pyrolysis.

FVP of 2-methoxy-N-(arenylidene)anilines gave benzoxazoles¡Fboth FVP and photolysis of 2-thiomethoxy-N-(arenylidene)anilines gave benzothiazoles.

Pyrolysis of 3- (o-methoxyphenyl)-1-phenylprop-2-en-1-one(49) ¡B1- (o-methoxyphenyl)-3-phenylprop-2-en-1-one (50) and 1-(o-methoxyphenyl)-3-phenylprop -2-yn-1-one (51) gave the expected cyclic products 2-phenylbenzo[b]furan (11) and flavone (73). Furthermore, compounds 49-51 gave phenanthrene-9,10-dione (71)¡Bfluoren-9-one (14) and others as the minor products at high temperture. Under photolytic condition, compounds 49-51 gave photocyclic product (73) all in low yields and recovered mostly the starting materials.

Flash vacuum pyrolysis (FVP) of azidomethylthiophene, via a nitrene intermediate, gave a trimer (N,N`-trifurfurylidene-furfurylidene diamine). Use three kinds of methods to synthies benzofuran compound and gain the product by using the third method.

¤@.Pyrolysis of 2-thiomethoxystyrylarenes 15a-c gave 2-(aryl-2-yl)benzo[b]arenes 22a-c and their isomers 23a-c and polycyclic aromatic hydrocarbons (PAH) 24a-c, respectively. Furthermore, pyrolysis of 15c also gave compounds 42¡B43¡B44 by breaking C-N single bond of 15c at higher temperature. In addition, photolysis of 15a-c gave photocyclic products 24a-c and 32a-c, respectively. ¤G.Pyrolysis of 2-(3-phenylpropenyl)anisole(18) and 2-(1-phenyl)anisole (19) gave 2-phenylbenzo[b]furan (13)¡Bbenzofuran (27)¡Bethylbenzene (28) and dibenzyl (29) as the main products. ¤T.Attempts to prepare hexaazatriphenylene derivatives 3 were carried by condensation between diamino dihydropyrazine compound 2 and hexaketocyclohexane (1).