Robert E. Mammarella

gem-chloro(trimethylsilyl)allyllithium: A novel ambident nucleophile

Abstract gem-Chloro(trimethylsilyl)allyllithium, Li(Me3SiCClCHCH2), was prepared by the transmetalation reaction between Ph3PbCH2CHC(Cl)SiMe3 and n-butyllithium in THF at −90°C. The terminus at which new bond formation occurs in reactions of this ambident nucleophile appears to be determined by electronic and steric factors. Reactions of this reagent with trimethylchlorosilane, trimethyltin chloride, iodomethane, aqueous HCl, aldehydes (n-C6H13CHO, PhCHO) and ketones (CF3C(O)CH3, PhC(O)CH3, cyclohexanone) were carried out.

New functional allylic lithium reagents: gem-dialkoxyallyllithium reagents: a useful route to β-silyl- and β-stannylpropionate esters

Abstract The reaction of sec-butyllithium with acrolein dialkyl acetals in THF or in THF/Et 2 O/pentane at -95°C results in formation of gem -dialkoxyallyllithium reagents, Li[CH 2 CHC(OR) 2 ]. These react with organosilicon and organotin chlorides to give ketene acetals, R 3 SiCH 2 CHC(OR) 2 and R 3 SnCH 2 CHC(OR) 2 . The acid hydrolysis of these products produces β-substituted propionic acid esters, R 3 SiCH 2 CH 2 CO 2 R and R 3 SnCH 2 CH 2 CO 2 R. Reactions of these lithium reagents with allyl bromide gave esters of 5-hexonoic acid, CH 2 CH(CH 2 ) 3 CO 2 R (R = Me, Et).

The preparation of substituted allyllithium reagents from allyltin compounds by transmetalation

Abstract The reaction of substituted allyltrimethyltin compounds with methyl-lithium in tetrahydrofuran gave substituted allyllithium reagents. Reactions of the latter with trimethylchlorosilane, iodomethane (or benzyl bromide) and carbonyl compounds were examined.

Halomethyl—metal compounds : LXXIV. Organolead compounds as precursors for halo- carbenes

Abstract The following organolead compounds were prepared and investigated as potential divalent carbon transfer agents: Ph3PbCCl3, Ph3PbCBr3, Ph3PbCCl2Ph, Ph3PbCHCl2 and Ph3PbCHClF. Of these the CCl3, CBr3 and CHCl2 compounds were found to be useful carbene sources at higher (120–150°) temperature. The reaction of triphenylleadlithium with 3,3,3-trichloropropene gave hexaphenyldilead and Ph3PbCH2CHCC2, rather than the expected Ph3PbCCl2CHCH2.

The reaction of 3,3-dichloroallyltrimethylsilane with n-butyllithium

Abstract n-Butyllithium reacts with 3,3-dichloroallyltrimethylsilane to metalate the vinyl proton. Under the reaction conditions the Me3SiCH2C(Li)CCl2 formed undergoes β-elimination of LiCl to give ClCCCH2SiMe3 whose subsequent reaction with n-butyllithium produces LiCCCH2SiMe3. Addition of trimethylchlorosilane gives Me3SiCCCH2SiMe3. When two molar equivalents of n-butyllithium are used, further metalation of LiCCCH2SiMe3 gives LiCCCH(Li)SiMe3. The action of N-bromosuccinimide on Me3SiCH2CHCCl2 resulted in formation of Me3SiCHCHCCl2Br.

THE PREPARATION OF ALLYLIC DERIVATIVES OF TIN BY WITTIG REACTIONS OF β‐(TRIMETHYLSTANNYL)ETHYLIDENETRIPHENYLPHOSPHORANE

Das uberraschenderweise bei Zimmertemperatur stabile, aber nicht in reiner Form isolierbare Phosphoniumsalz (IV) last sich bei niederen Temperaturen zum Ylid (V) umsetzen, das ebenso wie (IX) mit Aldehyden oder Ketonen zu den Allylstannanen (VI), (VII) oder (X) umgesetzt werden kann.