Donatella Furlani

Hydrated σ-bonded organometallic cations in organic synthesis: I. Allyl-, crotyl-, 1-methylallyl-, cyclohex-2-enyl-, and cinnamyl-stannation of carbonyl compounds in water

Homoallylic alcohols can be prepared in water by allyl-, crotyl-, 1-methylallyl-, cyclohex-2-enyl-, or cinnamyl-stannation of such carbonyl compounds as aldehydes, dialdehydes, and ketones, as well as acetals. The procedure is based on: Bu2RSnCl + R′COR″ + 12H2O → R(HO)CR′R″ + 12(Bu2SnCl)2O ↓ where R = allyl, crotyl, 1-methylallyl, cyclohex-2-enyl, or cinnamyl group, R′ = H or alkyl group, R″ ≠ R′ = alkyl group. In most cases, the reaction products are obtained rapidly in high yields (80–100%). Hydrated organometallic cations Bu2RSn+(aq) are partly involved. These results, together with those already published on 2-propynyl- and allenyl-stannation, indicate the value of this procedure.

Allylstannation: IX. The preparation of 4-chloro-2,6-dialkyl-, 4-bromo-2,6-dialkyl-, (E/Z)-4-chloro-2,6-dialkyl-3-methyl-and (E/Z)-4-bromo-2,6-dialkyl-3-methyl-tetrahydropyrans by condensation of aldehydes with di- and tri-halides of allyltin

Abstract The reaction recently discovered leading to tetrahydropyrans (THP): has been more extensively investigated by using various allyltin systems, alternate incremental additions of two aldehydes, and scrambling organotin reagents. Unsymmetric halotetrahydropyrans containing various R groups can be readily prepared in this way. The thermal breakdown of the 1 2 -dichloro adducts, namely ( E/Z )1-alkyl-1-butyldichlorostannoxy, 1-alkyl-3-pentyl ethers and the ( threo/erythro )-1-alkyl-1-butyldichlorostannoxy, 1-alkyl-2-methyl-3-butenyl ethers, is a stereospecific reaction which affords ( E/Z )-halotetrahydropyrans, where the isomerism is at the CHClCH(CH 3 ) bond.

Organotins as etherfication catalysts. 11. catalytic conversion of alcohols to open-chain and cyclic ethers by organotin trichlorides

Abstract 1,5-Heptadien-4-ol and various 1,4- and 1,5-glycols are catalytically converted to open-chain and cyclic ethers respectively in the presence of butyltin trichloride. The dehydration of alcohols is mediated by formation of organoalkoxytin dihalides BuSn(OR)Cl 2 A mechanism for the formation of these ethers is proposed. The catalytic activity of other organotins together with SnCl 4 has been examined for the conversion of 1,5-pentanediol to THP; the scale of the catalytic efficiency is: MeSnCl 3 ⩾PhSnCl 3 SnCl 4 BuSnCl 3 Me 2 SnCl 2 Bu 2 SnCl 2 ≫ [Bu 2 SnCl] 2 O.

The crystal structure of triphenylallyltin

Abstract The crystal structure of (C 6 H 5 ) 3 SnCH 2 CHCH 2 has been determined. The asymmetric unit consists of two molecules of triphenylallyltin having virtually the same conformation. Their geometrical parameters exclude p π - d π bonding between the metal and the allyl double bond, and seem to be in a better agreement with a σ-π conjugation effect.

Crystal and molecular structures of dicyclohexyltin dichloride and dibromide

Abstract The crystal structures of (C 6 H 11 ) 2 SnCl 2 ( A ) and (C 6 H 11 ) 2 SnBr 2 ( B ) have been determined. The compounds are isomorphous, and the molecules have nearly the same geometry. In both cases the coordination can be regarded as tetrahedral on the basis of the geometrical parameters. The data are critically analysed with that published for analogous compounds.

Hydrated σ-bonded organometallic cations in organic synthesis

Homoallylic alcohols can be prepared in water by allyl-, crotyl-, 1-methylallyl-, cyclohex-2-enyl-, or cinnamyl-stannation of such carbonyl compounds as aldehydes, dialdehydes, and ketones, as well as acetals. The procedure is based on: Bu2RSnCl + R′COR″ + 12H2O → R(HO)CR′R″ + 12(Bu2SnCl)2O ↓ where R = allyl, crotyl, 1-methylallyl, cyclohex-2-enyl, or cinnamyl group, R′ = H or alkyl group, R″ ≠ R′ = alkyl group. In most cases, the reaction products are obtained rapidly in high yields (80–100%). Hydrated organometallic cations Bu2RSn+(aq) are partly involved. These results, together with those already published on 2-propynyl- and allenyl-stannation, indicate the value of this procedure.

HYDRATED SIGMA-BONDED ORGANOMETALLIC CATIONS IN ORGANIC-SYNTHESIS .1. ALLYL-STANNATION, CROTYL-STANNATION, 1-METHYLALLYL-STANNATION, CYCLOHEX-2-ENYL-STANNATION, AND CINNAMYL-STANNATION OF CARBONYL-COMPOUNDS IN WATER

Homoallylic alcohols can be prepared in water by allyl-, crotyl-, 1-methylallyl-, cyclohex-2-enyl-, or cinnamyl-stannation of such carbonyl compounds as aldehydes, dialdehydes, and ketones, as well as acetals. The procedure is based on: Bu2RSnCl + R′COR″ + 12H2O → R(HO)CR′R″ + 12(Bu2SnCl)2O ↓ where R = allyl, crotyl, 1-methylallyl, cyclohex-2-enyl, or cinnamyl group, R′ = H or alkyl group, R″ ≠ R′ = alkyl group. In most cases, the reaction products are obtained rapidly in high yields (80–100%). Hydrated organometallic cations Bu2RSn+(aq) are partly involved. These results, together with those already published on 2-propynyl- and allenyl-stannation, indicate the value of this procedure.

Gas-liquid chromatography, thin-layer chromatography and carbon-13 nuclear magnetic resonance spectrometry in the analysis of diastereomeric mixtures of RCH(OH)CH(CH3)CHCH2 alcohols

Abstract Gas-liquid chromatography, thin-layer chromatography and 13 C NMR spectrometry have been employed to identify and analyse diastereomeric mixtures of the β-methylalcohols RCH(OH)-CH(CH 3 )-CHCH 2 where R = CH 3 , C 2 H 5 , n -C 3 H 7 , n -C 4 H 9 , n -C 5 H 11 , iso -C 3 H 7 , sec. -C 4 H 9 , tert. -C 4 H 9 . The existence of a relationship between the analytical data and diastereomeric configuration of the alcohols is pointed out for all the three methods adopted.