Stannane, tributyl-2-propenyl

Benzyloxyacetaldehyde Acetaldehyde, (phenylmethoxy)- (9) (60656-87-3) Allyltributylstannane Stannane, allyltributyl- (8) Stannane, tributyl-2-propenyl- (9) (24850-33-7)... 

Allyl bromide 1-Propene, 3-bromo- (106-95-6), 76, 60, 221 L-ALLYLGLYCINE 4-PENTENOIC ACID, 2-AMINO-, (R)- (54594-06-8), 76, 57 Allylic alcohols, enantioselective cyclopropanation, 76, 97 Allylmagnesium bromide Magnesium, bromo-2-propenyl- (1730-25-2), 76, 221 Allylmagnesium bromide (ethereal complex solution), 76, 221 Allylmagnesium bromide (THF complex solution), 76, 222 Allyltributylstannane Stannane, tributyl-2-propenyl- (24850-33-7), 75,12... 

SYNS 2-METHYK2-PROPENOIC ACID METHYL ESTER, POLYMER with TRIBUTYL((2-METHYL-1 -0X0-2-PROPENYL)OXY)STANNANE TRIBUTYL(METH-ACRYLOYLOXY)-STANNANE POLYMER with METHYL METHACRYLATE (SCI)... 

SYNS TRIBUTYL(METHACRYLOYLOXY)STANNANE TRIBUTYL((2-METHYL-l-OXO-2-PROPENYL)OXY)-STANNANE TRIBUTYLSTANNYL METHACRYLATE TRIBUTYLTIN METHACRYLATE... 

R1 = H R2 = CH3 tributyI(l-methyI-2-propenyI)stannane%, yield 74% Tributyl(l-methyl-2-propenyl)stannane Typical Procedure33 ... 

Both allylstannane transmetalation and thermolysis of homoallyl stannoxanes have been used to prepare 2-butenyltin halides as (E)j(Z) mixtures44-45. The reaction between 2-butenyl-(tributyl)stannane and dibutyltin dichloride initially provides dibutyl(l-methyl-2-propenyl)tin chloride as the kinetic product by an SE2 process, but this isomerizes under the reaction conditions to give a mixture containing the (Z)- and (E)-2-butenyl isomers46. 

Excellent chelation control was observed using tributyl(2-propenyl)stannane and a-benzyloxy-cyclohexaneacetaldehyde with magnesium bromide or titanium(IV) chloride, whereas useful Cram selectivity was observed for boron trifluoride-diethyl ether complex induced reactions of the corresponding ferr-butyldimethylsilyl ether89. 

The boron trifluoride-diethyl ether complex induced reaction of 2-butenyl(tributyl)-stannane and 3-(/er/-butyldimethylsilyloxy)-2-methylpropanal gave predominantly the nonchelation-controlled yyn-product93, whereas with the analogous 3-benzyloxyaldehyde, 2-propenyl-tin trichloride, generated in situ from tributyl(2-propenyl)stannanc and tin(IV) chloride, gave the chelation-controlled product93. 

The best procedure reported to date for the asymmetric allylation of aldehydes using tributyl(2-propenyl)stannane involves the catalyzed addition with the BINOL-TiCl2 complex as catalyst. Good yields and ee s were obtained for both aromatic and aliphatic aldehydes using 20 mol% of the catalyst127. 

Tributyl(l-ethoxy-2-propenyl)stannane (2) was first prepared from tributyl[chloro(ethoxy)-methyl]stannane and vinylmagnesium bromide, and found to be unstable with respect to 1,3-migration of the tributyltin substituent101. Tributyl(l-ethoxy-3-methyl-2-butenyl)stannane (1) was found to be more stable, and has since been prepared directly from (tributyl)(diethoxy-methyl)stannane and 2-methylpropenylaluminum dichloride generated in situ102. 

Stannylation of lithiated allyl ethers gives (Z)-3-alkoxyallylstannanes (1)115,116, whereas mixtures of (Z)- and ( )-tributyl(3-methoxy-2-propenyl)stannanes (2) were obtained from free-radical addition of tributyltin hydride to l-methoxy-l,2-propadienel16. 

S)-tributyl[t-alkyl-3-(methoxymethoxy)-2-propenyl stannane yield 80% 90-95% ee... 

Representative procedure for the synthesis of (Z)-a-selenenylvinylstannanes [34] A mixture of Cp2Zr(H)Cl (1.1 mmol) and (3-methoxy-l-propynyl)tributylstannane (1.0 mmol) in THF (5 mL) was stirred at room temperature for 20 min. A solution of PhSeBr (1.0 mmol) in THF (4 mL) (prepared in situ) was then injected into the resulting solution and the mixture was stirred at room temperature for 30 min. It was then diluted with light petroleum and stirred for a further 5 min., after which the supernatant was filtered through a short plug of silica gel. After evaporation of the solvent from the filtrate, the residue was purified by preparative TLC on silica gel to yield (lZ)-tributyl-[3-methoxy-l-(phenylse-leno) -1 -propenyl] stannane (60 %). 

Die reduktive Denitrierung von / -Nitro-a-(2-propinyloxy)- bzw. / -Nitro-a-(2-propenyl-oxy)-Verbindungen mit Tributyl-stannan fiihrt fiber radikalische Alkyl- bzw. Cycloalkyl-Zwischcnstufen zu Tetrahydrofuran-Derivaten2 ... 

In a similar reaction, chiral oxazolidine amides are used as chiral auxiliaries92. The amide-substituted radical, generated via the addition of cyclohexyl radicals to the corresponding alkene, undergoes addition to tributyl(2-propenyl)stannane with significant diastereoselectivity. The monoadduct is formed in a ratio of 96 4 and for the diadduct only one major diastereomer is... 

Phenylmenthyl esters are also suitable chiral groups for inducing stereoselectivity in radical addition reactions, as shown in the allylation of phenylmenthyloxycarbonyl-substituted xanthates. The photoinitiated reaction of the radical precursor with tributyl(2-propenyl)stannane at — 78 =C affords only one diastereomer4. The absolute configuration of (— )-8-phenylmenthyl 2-methyl-2-phenyl-4-pentenoate (5) is not known. 

In the C -C bond formation of more complex cyclic systems, such as the steroid derivative ethyl 3/J-(/tTt-butyldimethylsiIyloxy)-20-phenylseleno-5-pregnen-21-oate, 1.2-induction is also effective 10. Reaction with tributyl(2-propenyl)stannane yields the diastcrcomeric steroids in a ratio of 90 10. 

The reaction of ethyl l-iodo-l-(4-methylphenylsulfinyl)propanoate with tributyl(2-propenyl)stannane is highly stereoselective12. Only a trace amount of a second diastereomeris formed. 

Tabic 1. Allylation of 6-Bromopenicillanic Acid Derivatives with Tributyl(2-propenyl)stannane... 

Cyclopentyl radicals flanked with /1-substituents on both sides are formed in reactions of 3-alkyl-2-phenylselenocyclopentanones36. After photochemical initiation, the cyclopentyl radical is formed through abstraction of the phenylseleno group. Addition to tributyl(2-propenyl)stannane occurs preferentially trans to the / -alkyl substituent and consecutive elimination of the stannyl radical gives the final allylation product. It has also been reported37 that addition of the /1-methyl cyclopentyl radical to 2-propenenitrile occurs with d.r. (transjeis) 92 8, hence it seems likely that the carbonyl group adjacent to the radical center reduces the selectivity. 

No addition occurs any longer when the 3-butenyl chain is replaced by the homologous 3-pentenyl group.However, the nonterminal double bond effectively participates in an intramolecular S 2 -process (Scheme 1-104) that converts tributyl[(2-hexyl-5-methoxy-5-methyl-3-hexenyl)oxymethyl]stannane through the lithiated species into 2-hexyl-5-(2-methyl-l-propenyl)tetrahydrofiuan (143 87%, cis /trans 91 9). 

Hanamoto T, Hakoshima Y, Egashira M. Tributyl(3,3,3-tri-fluoro-l-propenyl)stannane as an efficient reagent for the... 

---