Sinpei Kozima

Formation of organotin-nitrogen bonds IV. N-trialkyltin derivatives of 4-mono- or 4,5-disubstituted 1,2,3-triazoles, 3-phenyl-1,2,4-triazole, 3-phenylpyrazole and 4-phenylimidazole☆

Abstract N -(Trialkylstannyl)-4-mono- or 4,5-disubtituted 1,2,3-triazoles have been prepared by the 1,3-cycloaddition of tri-n-butyltin azide to alkynes and by the condensation of 1,2,3-triazoles with bis(tri-n-butyltin) oxide or trimethyltin hydroxide. The trialkyltin group has been shown to be attached to the 2-nitrogen of the 1,2,3-triazole ring. N -Tri-n-butyltin derivatives of 3-phenylpyrazole, 4-phenylimidazole and 3-phenyl-1,2,4-triazole have been prepared by the condensation of bis(tri-n-butyltin)oxide with the corresponding azoles, the tri-n-butyltin group becoming attached to the 1-nitrogen atom of the latter.

Reaction of diphenyltin with alkyl halides nuclear magnetic resonance spectra of methyltin and ethyltin compounds

Abstract Treatment of diphenyltin, (Ph 2 Sn) m , with alkyl halide, RX, afforded Ph 2 RSnX, Ph 3 SnX, PhRSnX 2 , PhR 2 SnX and Ph 2 SnX 2 . The mode of formation of these compounds was studied. The NMR spectra of the mixed tetra-substituted methyl and ethyltin compounds were studied systematically. Shielding constants for chemical shifts, and empirical parameters for coupling constants of the respective substituents were determined.

TRIFLATE ION-PROMOTED ADDITION REACTIONS OF ALLYLSILANE TO QUINOLINES AND ISOQUINOLINES ACYLATED BY CHLOROFORMATE ESTERS

Abstract Reaction of allyltrimethylsilane with a variety of quinolines acylated by chloroformate esters can be promoted by a catalytic amount of a triflate ion to afford 2-allyl-1,2-dihydroquinolines in good to high yields. A similar reaction with isoquinolines afforded benzoisoquinuclidine derivatives by consumption of 2 eq of allyltrimethylsilane.

Facile addition reactions of allylsilanes to quinolines and isoquinolines activated by chloroformate ester and a catalytic amount of triflate ion

Abstract Addition reactions of allylsilanes to quinolines acylated by chloroformate esters are promoted by a catalytic amount of triflate ion to give 2-allyl-1,2-dihydroquinoline derivatives in good yields. A variety of functional groups on quinoline ring are tolerated in the reaction. The similar reactions of allylsilanes with isoquinolines afford cyclized benzoisoquinuclidine derivatives in good yields, along with 1-allyl-1,2-dihydroisoquinoline derivatives, depending on the reaction conditions. In addition, 2-substituted allylic silanes can be utilized in the present addition reactions to afford the 2-substituted and 1-substituted 1,2-dihydro-quinolines and -isoquinolines, respectively.

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.

Formation of organotin-nitrogen bonds : VII. Structural studies of 2-(trialkylstannyl)-4,5-bis(alkoxycarbonyl)-1,2,3-triazoles by 13C-NMR spectroscopy

Abstract The structure of N-(trialkylstannyl)-4,5-bis(alkoxycarbonyl)-1,2,3-triazoles has been studied by 13C-NMR spectroscopy. The trialkylstannyl group has been found to be attached to the 2-nitrogen atom of the 1,2,3-triazole ring.

Diorganostannylenes : III. Formation of dimethylstannylene from 1,1-dimethyl-2,3,4,5-tetraphenyl-1-stannacyclopentadiene and acetylenes

Abstract Dimethylstannylene, (CH 3 ) 2 Sn:, was formed transiently in the reaction of 1,1-dimethyl-2,3,4,5-tetraphenyl-1-stannacyclopentadiene (stannole) with dimethyl acetylenedicarboxylate or phenylacetylene. When this reaction was carried out in the presence of n-butyl bromide, dimethylstannylene inserted into the CBr bond of n-butyl bromide to give n-butyldimethyltin bromide in 12% yield, but most of the dimethylstannylene was captured by dimethyl acetylenedicarboxylate to give a complex. The complex was also produced in the photolytic reaction of the dimethyltin polymer, [(CH 3 ) 2 Sn] m , with dimethyl acetylenedicarboxylate. With phenylacetylene, dimethylstannylene did not give a similar complex, but polymerized to give the dimethyltin polymer.

The reaction of optically active (1-methyl-2,2-diphenylcyclopropyl)trimethyltin with bromine or iodine

Abstract Reaction of an optically active (1-methyl-2,2-diphenylcyclopropyl)trimethyltin (I) with bromine (or iodine) afforded 1-bromo-(or iodo)-1-methyl-2,2-diphenylcyclopropane (II) with a small degree of retention of configuration. This is best interpreted in terms of radical mechanism for the cleavage of the cyclopropyl carbontin bond in (I) by bromine or iodine.

An efficient asymmetric synthesis of allo- and pseudo-7,8-dimethoxyberbane systems through tin-mediated three component coupling

Abstract Three component coupling reactions of chiral 3-substituted 6,7-dimethoxy-3,4-dihydroisoquinoline with allylic tin reagents and unsaturated acid chlorides followed by intramolecular Diels-Alder reactions afford allo- and pseudo-7,8-dimethoxyberbane systems in high diastereomeric excess.

Direct Synthesis of Organotin Compounds V. Di- and trialkyltin chlorides and bromides

Abstract Di- and trialkyltin chlorides were prepared in good yields by the direct reaction of alkyl chloride with metallic tin when organic ammonium halides or a mixture of organic base and iodine-compound was used as the catalysts. Distribution of di- and trialkyltin chlorides varied with the kind and the amount of organic base, and reaction conditions. In the presence of a large amount of organic base, pure trialkyltin chloride was obtained. For the direct synthesis of alkyltin bromides, iodine source was not necessary.