A convenient method for the preparation of [1-2H]- and [1-3H]-terminal acetylenes

Conclusions A convenient one-step method has been proposed for the preparation of 1-isotope-substituted acetylenes based on the use of a phase transfer catalyst.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No, 8, pp. 1921–1922, August, 1985.     

A convenient synthesis of 1,2,4-triazolo[4,3,2-o,p]-[1,3]diazocino[4,5-b]quinoxalines via a 1,3-dipolar cycloaddition reaction and a ring transformation

The reaction of 6-chloro-2-hydrazinoquinoxaline 4-oxide 5 with triethyl orthoformate gave 7-chloro-1,2,4-triazolo[4,3-a]quinoxaline 5-oxide 6. The reaction of compound 6 with phenyl isocyanate afforded 7-chloro-4-phenylamino-1,2,4-triazolo[4,3-a]quinoxaline 7 , while the reaction of compound 6 with phenyl isothiocyanate resulted in deoxygenation to provide 7-chloro-1,2,4-triazolo[4,3-a]quinoxaline 8. However, the reaction of compound 6 with allyl isothiocyanate effected the 1,3-dipolar cycloaddition reaction, but not deoxygenation, to furnish 9-chloro-4,5-dihydroisoxazolo[2,3-a][1,2,4]triazolo[3,4-c]quinoxalin-5-ylmethylisothiocyanate 9. Moreover, the reduction of compound 9 with iron/acetic acid resulted in ring transformation to give 11 -chloro-7-hydroxy-4-thioxo-4,5,6,7,8,9-hexahydro-1,2,4-triazolo[4,3,2- o,p][1,3]diazocino[4,5-b]quinoxaline 10 , whose acetylation afforded 5-acetyl-11-chloro-7-hydroxy-4-thioxo-4,5,6,7,8,9-hexahydro-1,2,4-triazolo[4,3,2-o,p][1,3]diazocino[4,5-b]quinoxaline 11.     

A facile route to 2,4-dihydro-1H-benzo[d][1,3]thiazines via silver-catalyzed tandem addition-cyclization reactions

Tandem addition-cyclization reactions of 2-alkynylbenzenamines with isothiocyanates catalyzed by silver triflate are described; they provide an efficient and practical route for the synthesis of 2,4-dihydro-1 H-benzo[ d][1,3]thiazines.     

New cyclic sulfur ylides, 8-thiaazulenes. Syntheses and thermal rearrangements of 8-alkyl-1,3-diphenyldibenzo[e,h]-8-thiaazulenes 1)

A new cyclic sulfur ylide, 1,3-diphenyl-8-methyldibenzo[e,h]-8-thiaazulene was synthesized. 8-Alkyl-1,3-diphenyldibenzo[e,h]-8-thiaazulenes were thermally rearranged to give 1,2-rearranged products and 1,4-rearranged products.     

Synthesis of novel oxygen heterocycles: 1,10-dioxa-cyclopenta[a]fluorene and benzo[b]naphtho[2, 1-d]furans via Dötz intramolecular benzannulation

Novel fused heterocycles 1,10-dioxa-cyclopenta[a]fluorene and benzo[b]naphtho[2, 1-d]furans were synthesized via Dötz intramolecular benzannulation of alkyne tethered aryloxy chromium Fischer carbenes.     

Synthesis of dihydropyrazolo[3′,4′:3,4]pyrrolo[1,2-a]indoles and spiro-[3H-indole-3,3′-[Δ-1,2,4]-triazolin]-2-ones via intra and intermolecular 1,3-dipolar cycloadditions

A new class of dihydropyrazolo[3′,4′:3,4]pyrrolo[1,2-a]indoles and spiro[3H-indole-3,3′-[Δ²-1,2,4]-triazoline]-2-ones were synthesised via intra and intermolecular 1,3-dipolar cycloaddition reactions in good yields.     

Synthesis of spiro[2H-indole-2,1′-1H-isoindole]-3,3′-diones,spiro[1H-isobenzofuran-1,2′-2H-indole]-3,3′-diones and spiro[benzofuran-2,1′-isobenzofuran]-3,3′-diones via transannular reactions of eight membered ring intermediates

An auto oxidation-rearrangement product 4 was isolated from a high dilution reaction of ninhydrin with 3,4,5-trimethoxyaniline in water. A general synthesis of this compound and its derivatives 4–6 was devised by oxidation of tetrahydroindeno[1,2-b]indol-10-ones 1–3 with sodium periodate to give isoindolo[2,1-a]-indole-6,11-diones 4–6 in good yield. Compounds 4–6 can be easily transformed into spiro[1H-isobenzofuran-1,2′-2H-indole]-3,3′-diones 8–10 , spiro[2H-indole-2,1′-1H-isoindole]-3,3′-diones 11–13 and isoindole[1,2-a:2′,1′-b]pyrimidine-5,15-diones 15, 16 in high yields. Analogous reactions were performed on 3-amino-5a, 10a-dihydroxybenzo[b]indeno[2,1-d]furan-10-one ( 17 ) to give a dibenzoxocintrione 18 , spiro-[benzofuran-2,1′-isobenzofuran]-3,3′-dione 19 and an isoindol-1-one 20 .     

Photocyclization reactions. Part 4 . Synthesis of naphtho[1,8-bc]-furans and cyclohepta[cd]benzofurans using photocyclization of Ethyl 2-(8-Oxo-5,6,7,8-tetrahydro-1-naphthyloxy)acetates and ethyl 2-(5-Oxo-6,7,8,9-tetrahydro-5H-benzocyclohepten-4-yloxy)acetates

Photocyclization reactions were carried out on ethyl 2-(8-oxo-5,6,7,8-tetrahydro-1-naphthyloxy)acetates 1a-e and ethyl 2-(5-oxo-6,7,8,9-tetrahydro-5H-benzocyclohepten-4-yloxy)acetates 2a-e in acetonitrile. Irradiation of 1a-e gave naphtho[1,8-bc]furanols 3a-e and naphtho[1,8-bc]furans 4a-e in 33–83% yields and ethyl acrylates 5b-d were produced in 3–25% yields during irradiation of 1b-d . On the other hand, 2a-e afforded cyclohepta[ad|benzofuranols 6a-e and cyclohepta[ad]benzofurans 7a-e in 44–87% yields. Ethyl acrylates 8b-d were also produced in 7–43% yields from irradiation of 2b-d . Substituent effects on photocyclization and reaction pathways are discussed.     

The synthesis and transformations of 2H-naphtho-[1,2-b]pyran-2-one derivatives. Naphtho[2′,1′:5,6]-pyrano[3,4-d][1,3]oxazines and naphtho[1′,2′:5,6]pyrano[3,4-d]-pyrimidines,derivatives of two new heterocyclic systems

1,4-Naphthoquinone ( 1 ) was transformed with alkyl 2-aminofumarates 2 into 2H-naphtho[1,2-b]pyran-2-ones 3 and 4 , which served as intermediates in the synthesis of 7, 8 and 13 , which are derivatives of two new heterocyclic systems: naphtho[2′,1′:5,6]pyrano[3,4-d][1,3]oxazine and naphtho[1′,2′:5,6]pyrano[3,4-d]pyrimidine.     

The synthesis of novel polycyclic heterocyclic ring systems via photocyclization. 10. Synthesis and structure determination of naphtho[1′,2′:4,5]thieno[3,2-a]-4,7-phenanthroline

Naphtho[1′,2′:4,5]thieno[3,2-a]-4,7-phenanthroline, a novel hexacyclic ring system has been synthesized in four steps. The ¹H and ¹³C nmr assignments have been made using two-dimensional nmr techniques. The tertiary helical structure was determined by X-ray crystallographic analysis.     

A convenient method for the synthesis of 1-R-1,2,3,4-tetrahydrobenzothieno-[2,3-<Emphasis Type=Italic>c</Emphasis>]pyridine derivatives

New 1-R-2-methyl-1,2,3,4-tetrahydrobenzothieno[2,3-c]pyridine derivatives have been obtained by cyclization of 2-(1-benzothiophen-3-yl)ethylamines with aromatic and heteroaromatic aldehydes in the presence of triisopropylchlorosilane.     

A convenient method for constructing novel tetrahydropyrido[4′,3′:4,5]thieno[2,3-d]-pyrimidinones-carbohydrate and amino acid conjugates via copper(I)-catalyzed alkyne-azide ‘Click Chemistry’

Novel conjugates of tetrahydropyridothienopyrimidones and carbohydrates or amino acids linked by 1,2,3-triazoles were synthesized. After establishing the tetrahydropyridothienopyrimidones ring system by ring closure, propargyl groups were introduced by N-alkylation. Cu-catalyzed cycloaddition of the propargyl products with azido group containing hexoses or amino acids gives the corresponding 1,2,3-triazoles in high yields. This methodology also allowed attaching two carbohydrate molecules to the tetrahydropyridothienopyrimidone core. Interesting dependence of the regioselectivity of the N-propargylation of the pyrimidone ring on the exocyclic substituent found adjacent to the pyrimidine-N-atom was observed. A remarkable case of a non-catalyzed intramolecular [3+2]-cycloaddition of an alkyne with an azide to a 1,2,3-triazole was observed, which occurred in the solid state at rt or below.     

Synthesis of some complex pyrano[2,3-b]- and pyrido[2,3-b]quinolines from simple acetanilides via intramolecular domino hetero Diels-Alder reactions of 1-oxa-1,3-butadienes in aqueous medium

Some complex pyrano[2,3-b]- and pyrido[2,3-b]quinolines were synthesized from simple acetanilides via intramolecular domino hetero Diels-Alder reactions of 1-oxa-1,3-butadienes using water as solvent.     

A facile method for the stereoselective preparation of (1E,3E)-4-substituted-1-amino-1,3-dienes via 1,4-elimination

The 1,4-elimination reaction of 1-amino-4-methoxy-(2Z)-alkenes is shown to proceed with high (1E,3E)-stereoselectivities to afford the corresponding 4-substituted-1-amino-1,3-dienes in good yield. The scope and stereochemical features of the synthetic method are described.     

Synthesis of 8,9-(1,3-benzodioxolo-5,6)-5-azatricyclo[8.2.1.0<Superscript>1,5</Superscript>]tridec-11-en-6-one. A convenient route to structural analogs of the alkaloid cephalotaxine

A synthetic route to 8,9-(1,3-benzodioxolo-5,6)-5-azatricyclo[8.2.1.0^1,5]tridec-11-en-6-one structurally isomeric to the pentacyclic cephalotaxine nucleus is suggested. The route is based on the sequence including diallylboration of 2-pyrrolidinone and intramolecular metathesis of the resulting 2,2-diallylpyrrolidine, giving rise to 1-azaspiro[4.4]non-7-ene. This product was N-acylated with 6-bromohomopiperonylic acid chloride and then subjected to intramolecular cyclization according to the Heck reaction. Dedicated to Academicians A. L. Buchachenko and N. S. Zefirov on the occasion of their 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2160–2163, September, 2005.     

Some cyclization reactions of 1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-one: preparation and computational analysis of non symmetrical zwitterionic biscyanines

Regioselective nucleophilic addition of bisnucleophiles 1,2-benzenediamine, 2-amino-benzenethiol, and N-phenyl-1,2-benzenediamine to 1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-one (1) at C6 followed by intramolecular cyclocondensation at the C7 carbonyl afforded highly coloured tetracenes 1,3-diphenyl-1,6-dihydro-[1,2,4]triazino[5,6-b]phenazin-4-ium 4-methylbenzenesulfonate (12), 1,3-diphenyl-1H-[1,2,4]triazino[6,5-b]phenothiazine (14) and 1,3,11-triphenyl-1,6-dihydro-[1,2,4]triazino[5,6-b]phenazin-11-ium 4-methylbenzenesulfonate (15), respectively. Neutralization of the latter with alkali gave the free base 1,3,11-triphenyl-1H-[1,2,4]triazino[5,6-b]phenazin-11-ium-6-ide (16). Furthermore, the benzotriazinone 1 reacts with dimethyl malonate to give 6-(methoxycarbonyl)-7-oxo-1,3-diphenyl-7H-benzofuro[5,6-e][1,2,4]triazin-1-ium-4-ide (17) in 74% yield, while with S(4)N(4) [5,6-c]-thiadiazolo-7-oxo-1,3-diphenyl-1,2,4-benzotriazine (22) was formed in 15% yield. The free bases 16 and 17 display negative solvatochromism, which supports charge separated ground states similar to those of zwitterionic biscyanines, and DFT calculations at the UB3LYP/6-31G(d) level afford ΔE(ST) values of -13.6 and -18.7 kcal mol(-1), respectively that strongly favour the singlet ground state. All ring systems described are new and fully characterized.     

New regio-selective method of combinatorial synthesis of substituted thiophenes,thieno[3,2-b]pyridines and other heterocycles via combination of ‘domino’-type reactions

We present a novel combinatorial multicomponent regio-selective approach towards the synthesis of thieno[3,2-b]pyridines and pyridine pyrans. The methodology is based on the ‘domino’-type reaction. The high regio-selectivity in this reaction is gained by the in situ generation of the mono-potassium salt of 2-cyano-1-mercaptoethenethiolate. We also demonstrate that the use of ethyl 2-cyanoacetate in this reaction as a CH-acid leads to the termination of the domino sequence at the Dieckmann condensation step and yields novel ethyl 3-(4-cyano-3-hydroxy-5-(alkylthio)thiophen-2-yl)-3-oxopropanoate.