Tetsuo Nozoe

The formation of azulene derivatives from 2H-cyclohepta[b]furan-2-one derivatives

Abstract 3-Ethoxycarbonyl- and 3-acetyl-2H-cyclohepta[b]furan-2-ones react easily with malonitrile. cyanoacetamide, ethyl cyanoacetate and diethyl malonate, in the presence of sodium ethoxide or t-butyl-amine, giving the corresponding 1,2,3-trisubstituted azulene derivatives, respectively. The structures of these azulene derivatives are determined on the basis of chemical evidence, and spectral data. Considering the structural correlation between the starting 2H-cyclohepta[b]furan-2-ones and the azulene derivatives obtained, a reasonable reaction course, involving the heptafulvene-type and dihydroazulene-type intermediates, is presented for the formation of azulene derivatives from 2H-cyclohepta[b]furan-2-ones.

A convenient, one-pot azulene synthesis from cyclohepta[b]furan-2-ones and vinyl ether and its analogues. II: Acetals as reagent

Title synthesis by the reaction of cyclohepta[b]-furan-2-ones with acetals of several aldehydes and ketones on heating at 160-190 o C in neat or aprotic solvent

Mass spectrometry in structural and stereochemical problems—XXXVII. : Tropone and tropolone derivatives☆☆☆★

Abstract The general observation is made that on electron impact the molecular ions of tropone derivatives eliminate carbon monoxide as a neutral molecule and the resultant ions behave as benzene derivatives. Exceptions from this rule can be explained in terms of the presence of specific structural features.

A convenient, one-pot synthesis of azulenes having versatile functional groups by the reaction of 2H-cyclohepta[b]furan-2-ones with furan derivatives

2-Acylmethyl- and 2-methoxycarbonylmethylazulene derivatives having versatile functional groups in the side chain, are synthesized in one-pot by the reaction of 2H-cyclohepta [b] furan-2-ones with furans on heating at 160-190 ° C in aprotic solvent

The reaction of 2-arylsulfonyloxytropones and active methylene compounds: The formation of 8-hydroxy-2H-cyclohepta[b]furan-2-one and 2-amino-8H-cyclohepta[b]furan-8-one derivatives

Abstract Reaction of 2-arylsulfonyloxytropones (IV) and active methylene compounds, diethyl malonate, ethyl acetoacetate, ethyl cyanoacetate, malononitrile or cyanoacetamide, in the presence of NaOEt give 8-hydroxy-2H-cyclohepta[b]furan-2-one derivatives (V) and/or 2-amino-8H-cyclohepta[b]furan-8-one derivatives (VII), in addition to azulene derivatives (1) or 2H-cyclohepta(b]furan-2-one derivatives (II), known to be obtained by the reaction of 2-chlorotropones or 2-methoxytropones with active methylene compounds. Relative yields of products are influenced markedly by conditions, e.g. base type or molar ratios. The formation of V and VII is characteristic of 2-arylsulfonyloxytropones, not being observed with 2-chlorotropones or 2-methoxytropones. A reaction course involving elimination of the arylsulfonyl group as arenesulfinate ion is presented.

Electronic structure and kinetic behavior of 4-(cycloheptatrienylidene)cyclohexa-2,5-dienone (or [6.7]Quinaren-9-one) and its derivatives)

Abstract The conjugative interaction between the two terminal groups in title quinarenone 2 and its chloro- and methoxy-derivatives were evaluated, proving that the diatropicity of the seven-membered ring is a little larger in 2 than in tropone. Some of these quinarenones are also found to exist in equilibrium with their oligomers and show unexpectedly low barriers of rotation about the intercyclic bond.

Cyclohepta[b][1,4]benzoxazine and its related compounds. Some novel aspects in heterocyclic chemistry

Chemitry of cyclohepta [b] [1,4] benzoxazines and their related S- and O-analogues as well as of the related compounds without annulated benzene ring is reviewed

Cyclic cross-conjugated hydrocarbons having inserted p-quinoid ring—I : Diphenyl-p-tropylphenylmethyl cation formed on an attempted preparation of 1-cycloheptatrienylidene-4-diphenylmethylidene-2,5-cyclohexadiene

Abstract In connection with the synthetic studies of the cross-conjugated system 2 , p -(diphenylhydroxymethyl)phenyltropolidene ( 13 )* was prepared. On treatment with CF 3 COOH, 13 transformed to an aryltropylium ion ( 15 ) via an unstable blue colored compound. Based on NMR spectroscopy and some chemical properties the structure of the pigment is assumed to be diphenyl- p -tropylphenylmethyl cation ( 16 ) rather than the primarily anticipated cross-conjugated hydrocarbon 9,9-diphenyl[1.6.7]quinarene ( 6 ).

Structure and absolute configuration of α-kessyl alcohol and kessyl glycol

Abstract The structures and absolute configuration of α-kessyl alcohol (I) and kessyl glycol (II), sesquiterpenic constituents of Japanese valerian roots, have been established on the basis of chemical and spectroscopic data.

Experimental and Theoretical Analyses of Azulene Synthesis from Tropones and Active Methylene Compounds: Reaction of 2-Methoxytropone and Malononitrile

A representative azulene formation from an active troponoid precursor (2-methoxytropone) and an active methylene compound (malononitrile) has been analyzed both experimentally and theoretically. (2)H-Tracer experiments using 2-methoxy[3,5,7-(2)H(3)]tropone (2-d(3)) and malononitrile anion give 2-amino-1,3-dicyano[4,6,8-(2)H(3)]azulene (1-d(3)) in quantitative yield. New and stable (2)H-incorporated reaction intermediates have been isolated, and main intermediates have been detected by careful low-temperature NMR measurements. The detection has been guided by mechanistic considerations and B3LYP/6-31(+)G(d) calculations. The facile and quantitative one-pot formation of azulene 1 has been found to consist of a number of consecutive elementary processes: (a) The troponoid substrate, 2-methoxytropone (2), is subject to a nucleophilic substitution by the attack of malononitrile anion (HC(CN)(2)(-)) to form a Meisenheimer-type complex 3, which is rapidly converted to 2-troponylmalononitrile anion (5). (b) The anion 5 is converted to an isolable intermediate, 2-imino-2H-cyclohepta[b]furan-3-carbonitrile (6), by the first ring closure in the reaction. (c) A nucleophilic addition of the second HC(CN)(2)(-) toward the imine 6 at the C-8a position produces the second Meisenheimer-type adduct 7. (d) The second ring closure leads to 1-carbamoyl-1,3-dicyano-2-imino-2,3-dihydroazulene (11). A base attacks the imine 11, which results in generation of a conjugate base 12 of the final product, azulene 1.