Mituyosi Kawanisi

On the regioselectivity of the reaction of N-methoxycarbonylpyridinium chloride with Grignard reagents: highly regioselective synthesis of 2-substituted N-methoxycarbonyl-1,2-dihydropyridines.

Abstract Whereas alkyl Grignard reagents undergo 1,2- and 1,4-additions to N-methoxycarbonylpyridinium chloride in a variable ratio, alkenyl and alkynyl Grignard reagents do the exclusive 1,2-addition to afford 2-substituted N-methoxycarbonyl-1,2-dihydropyridines in fair to excellent yields.

Photochemical reaction of benzopyridines with alkanoic acids : Novel reductive alkylation of acridine, quinoline and isoquinoline under decarboxylation

Abstract Photoreaction of acridine with aliphatic carboxylic acids results in decarboxylation and formation of 9-alkylacridans. Irradiation of δ-(9-acridyl)valeric arid or e-(9-acridyl)caproic acid yields spiro compounds, 9,9-tetramethylene- and 9,9-pentamethyleneacridan, respectively. Extention of the reaction to quinoline as a substrate gives rise to 2- and 4-alkylquinolines and 4-alkyl-1,2,3,4-tetrahydroquinolines. Similar treatment of isoquinoline gives 1-alkylisoquinolines. The mechanistic implication of the photoalkylation is discussed in terms of the acid-base equilibrium between carboxylic acid and the photoexrited nitrogen heterocycle.

Highly regio- and chemo-selective γ-addition of benzylic group to N-alkoxycarbonylpyridiniuin salts by means of organotin reagent

Abstract Benzyltin reagents undergo highly regio- and chemo-selective γ-addition to a variety of N -acylpyridinium salts to give4-benzyl-1,4-dihydropyridines exclusively in good yields.

Photochemical rearrangement of arenesulphonanilides to p-aminodiarylsulphones

Abstract Irradiation of arenesulphonanilides in an alcoholic solution induced the Fries-type rearrangement yielding p -amino-substituted diarylsulphones and arylamines. The absence of crossed rearrangement was observed upon photolysis of an equimolar mixture of p -toluenesulphonanilide and o -benzenesulphonotoluidide.

Photochemical reactions of trans-anethole

Abstract A novel dimer of trans-anethole has been obtained photochemically. The dimerization proceeds with strict stereospecificity and the structure of the dimer has been ascertained as 1,cis-2-di-p-anisyl-trans-3,trans-4-dimethylcyclobutane. The dimer was transformed into the corresponding diphenol, diacetate and 1,cis-2-dimethyl-trans-3,trans-4-diphenylcyclobutane. The hydrocarbon was independently obtained from β-truxinic acid by reduction. Some dimethyldiphenylcyclobutane isomers have been prepared analogously from cinnamic acid dimers and the NMR spectra have been compared. Anethole reacts photochemically with benzaldehyde and benzophenone to afford the corresponding oxetanes, some of which decompose spontaneously into stilbenes and acetaldehyde. The anethole dimer was not obtained in the presence of such carbonyl compounds, while isomerization to cis-anethole proceeds smoothly. Salicylaldehyde gives another type of 1:1-adduct, which has been shown to be 4-p-anisyl-2-hydroxy-3-methylchroman. An analogous hemiacetal was obtained by the reaction of salicylaldehyde and 1,1-diphenylethylene. Mechanistic implications of anethole photochemistry have been discussed.

Synthesis of 2-(1-Hydroxyalkyl)acrylonitriles by the Cocatalysis of a Base and an Acid

Abstract Titled compounds are synthesized in good yields from acrylonitrile and saturated aliphatic aldehydes by the cocatalysis of tributylphophine and triethylaluminium.

Diels-Alder reaction of methyl coumalate with 1,3-dienes

Abstract Reaction of methyl coumalate ( 1b ) with 1,3-butadienes at 100° afforded the tetrahydrocoumarins ( 6 ) and the 4-methoxycarbonyltricyclo[3.2.1.0 2,7 ]octenes ( 7 ). The similar reaction of 1b with cyclohexadiene gave exclusively tetrahydronaphthalene-2-carboxylate. With cyclopentadiene, 1b afforded a product ( 10 ) resulting from the addition reaction in which cyclopentadiene acted as a dienophile. The reaction giving 6 is the first example of the reaction of a 2-pyrone as a dienophile.

Photochemical reactions of allylphenoxide anions

Abstract Photochemical behaviour of sodium allylphenoxides 1a–3a was compared with that of corresponding neutral allylphenols 1b–3b, and a striking difference was found in reactivity as well as in course of the reaction. Remarkably higher photoreactivity of allylphenoxide anions, especially that of o-allylphenoxide 1a, is ascribed to the efficiency of electron transfer. The characteristic reaction products derived only from the anions were as follows: (a) intramolecular cyclization products, indanols 9, from 2a, (b) rearranged reduction products 10 from both 2a and 3a, and (c) degradative methanol-adduct 11 from 3a. Methanol-adducts 7 and photo-reduction products 6 were formed in either case. In addition cyclization products with the participation of O atom, 4 and 5, were obtained from 1a and 1b. Occurrence of the di-π-methane rearrangement was restricted to the reaction of neutral species 1b–3b. A mechanism based on electron transfer in the excited state is suggested for the course of the photoreaction.

Mechanistic studies on decomposition of trialkylstannyllithiums

The fast decomposition of trialkylstannyllithiums, R3SnLi (R = Me, Et and Bu), in the presence of hexaalkydistannanes, R3SnSnR3, was observed, and its mechanism was investigated kinetically. Partial dissociation of R3SnLi into a (RLi)(R2Sn:)¯ complex in a solvent cage is suggested to occur in the initial step. The RLi in the complex can be trapped instantaneously by R3SnSnR3 to afford R4Sn and R3SnLi, and the counterpart R2Sn: by R3SnLi giving R3SnR2SnLi. The decomposition of R3SnLi followed first- order kinetics within 3.5 h, corresponding well to the rate of disappearance of R3SnSnR3 and of appearance of R4Sn. The partial dissociation rate con- stant (k1) of Me3SnLi into the complex was determined as 2.0 X 10−3 min−1. The values of k1 are about 100 times those of rate constants (k′) for decom- position of R3SnLi in the absence of R3SnSnR3. Reformation of R3SnLi from the (RLi)(R2Sn:)¯ complex is highly significant.

Photochemistry of certain non-enolizable β-diketones

Abstract Photochemical rearrangement of 2,2,5,5-tetramethyl-1,3-cyclohexanedione (I) yields predominantly and enol δ-lactone V with an exocylic olefinic bond. A small amount of its more stable isomer VIII is also produced. Similar treatment of 2,2-dimethyl-1,3-cyclohexanedione (II) exclusively affords an exocylic enol δ-lactone VI. These enol lactones V and VI are reconverted photochemically into the respective diketones I and II in low yields, while VIII gives fragmentation products. Photolysis of an open-chain diketone, 3,3-dimethyl-2,4-pentanedione (XVI), gives the isomeric enol ester XXI along with biacetyl and 1,4-diketone XX, whereas photolysis of 2-acetyl-2-methylcyclohexanone (XXII) involves the so-called Type II reaction leading to a ring-cleavage product XXVI. The mechanistic implications of the photochemistry of I, V and VIII have been discussed.