Alicia D. Ayala

Organotin hydride additions to E- And Z-trisubstituted ethylenes synthesis of some new functionally substituted organotin compounds

Abstract The syntheses of some new functionally substituted organotin compounds are reported. The results indicate that the additions of tri-n-butyltin and tri-phenyltin hydrides to trisubstituted ethylenes (where one substituent is either a carbomethoxy or a nitrile group) proceed smoothly to give high yields of organotin adducts and that the reactions are stereoselective. Evidence concerning the reversibility of the free radical forming step is presented.

Organotin compounds: X. Organotin hydride addition to methyl cyclohexene-1-carboxylate and methyl indene-3-carboxylate

Abstract Free radical hydrostannation of methyl cyclohexene-1-carboxylate (I) and methyl indene-3-carboxylate (III) with trialkyltin hydrides, R 3 SnH (R  Me, n-Bu, Ph) gives the energetically unfavourable cis products, 2-trialkylstannyl cyclohexanecarboxylate (II) and 2-trialkylstannyl indane-1-carboxylate (IV) in high yields, via a trans addition of the tin hydrides. The hydride abstractions by the intermediate trialkylstannylcyclohexanyl (VIII) and trialkylstannylindanyl (IX) intermediate radicals take place stereospecifically, and exclusively from the less hindered ring side. The structures of the isomers II and IV were established by (a) their transformation into the corresponding chlorodialkylstannyl derivatives V and VI, which were shown spectroscopically to have cis stereochemistries by intramolecular complexation of the ester group, and (b) their NMR data. Full 1 H, 13 C, and 119 Sn NMR data are given.

Organotin compounds. IX: Reactions between trialkylstannyl-substituted esters and trimethylsilyl halides: exchange vs. hydrolysis

Abstract A study of the reactions between β- and ω-trialkylstannyl-substituted saturated methyl carboxylates (R  Me, n-Bu, Ph) and trimethylsilyl halides (X  Cl, Br, I) is reported. The results indicate that methyl β-(trialkylstannyl)propanoates react with trimethylsilyl halides to give alkyl/halide exchange products; no ester cleavage is observed even using organotin ester/silicon halide ratios of 1 4 . The reactions carried out with ω-trialkylstannyl-substituted esters show that the failure of methyl β-(trialkylstannyl)propanoates to give transesterification products is connected with the intramolecular coordination that exists in the methyl β-(halodialkylstannyl)propanoates, alkyl/halide exchange products, which prevents the coordination between the CO of the ester and the silicon halide. The results obtained also indicate that the alkyl/halide exchange reactions are much faster than the transesterification reactions. Evidence concerning the possibility that these halodealkylation reactions at tin might be a general property of tetralkyltin compounds is presented.

Organotin compounds: XI. Organotin hydride additions to various methyl dihydronaphthalenecar☐ylates

Abstract Free radical hydrostannation of methyl 3,4-dihydronaphthalene-1-car☐ylate (I), methyl 3,4-dihydronaphthalene-2-car☐ylate (III), and methyl 1,4-dihydronaphthalene-2-car☐ylate (V) with triorganotin hydrides, R 3 SnH (R = Me, n-Bu, Ph) gives the energetically unfavourable cis products, 2-triorganostannyl-1,2,3,4-tetrahydronaphthalene-1-car☐ylate (II), 1-triorganostannyl-1,2,3,4-tetrahydronaphthalene-2-car☐ylate (IV), and 3-triorganostannyl-1,2,3,4-tetrahydronaphthalene-2-car☐ylate (VI) in high yields, via a trans addition of the tin hydrides. The hydride abstractions by the intermediate 2-, 1-, 3-triorganostannyl-1,2,3,4-tetrahydronapththyl radicals (XI, XII and XIII respectively) take place stereospecifically and exclusively from the less-hindered ring side. The structures of the isomers II, IV, and VI, were established by (a) their transformation into the corresponding chlorodiorganostannyl derivatives VIII, IX, and X, which were shown spectroscopically to have cis stereochemistries by intramolecular complexation of the ester group, and (b) their NMR data. Full 1 H, 13 C, and 119 Sn NMR data are given.

Triphenylstannyl anions and related moieties as leaving groups in elimination reactions

Reactions of strong bases with β-triphenylstannyl substituted propionitriles give high yields of alkenes under mild conditions through, probably, an E1cB mechanism; under the same reaction conditions, β-trialkylstannyl substituted propionitriles give substantially lower yields of elimination products.