Robert F. Schmitz

Lithiated 2-alkynyl-1,3-dioxanes as fully oxygenated acyl-anion equivalents: synthesis of 1-alkynyl ketones

Abstract 2-Lithio-2-(trimethylsilylethynyl)-1,3-dioxane 3 is prepared from 2-(trimethylsilylethynyl)-1,3-dioxane with n-BuLi. Alkylation of 3 produces propargylic ketals 2 exclusively. Reaction with group IV-B chlorotrimethylimetalanes gives both propargylic products 2 and allenes 6 depending on the solvent used. Desilylation of 2 as well as hydrolysis to the alkynyl ketones 1 can be carried out under mild conditions. The first 1-alkynyl stannyl ketone has been prepared in this way. Formation of 2-lithio-2-(3,3-dimethyl-1-butynyl)-1,3-dioxane 10 requires t-BuLi. With various electrophiles 10 yields propargylic products and/or allenes in ratios depending on the solvent used.

REACTIONS OF THE BUTYLLITHIUMS WITH TERTIARY OLIGOETHYLENEPOLYAMINES

Abstract Complexes of t-BuLi monomer with 1,4,7-trimethyl-1,4,7-triazacyclononane (TMTAN, 3-CH 3 ) and tris(N,N-dimethyl-2-aminoethyl)amine ( 4-CH 3 ) were identified by 13 C-NMR. Rapid elimination of LiN(CH 2 CH 2 NMe 2 ) 2 takes place from the free CH 2 CH 2 NMe 2 group of t-BuLi· 4-CH 3 . BuLi complexes of hexamethyltriethylenetetramine ( 5-CH 3 ) and octamethylpentaethylenehexamine ( 6 ) behave similarly, as does 4-CH 2 Li . Complexes of BuLi oligomers are lithiated at free N-CH 3 .

Mixed tetramers of sec-butyllithium and 3-methoxypropyllithium ; degree of intracluster etheration and reactivity of sec-butyllithium towards ethylene

Abstract In benzene, neither sec -butyllithium ( 1 ) nor 3-methoxypropyllithium ( 2 ) react with ethylene, while in solutions containing 1 plus 2 3-methylpenty- llithium ( 3 ) is produced by ethylenation of 1 . Clusters 1 n 2 4−n (n: 0 – 4) are indicated by NMR and 1 2 2 2 is deduced to be the most reactive species. At [ 2 ]:[ 1 ] = 2, the reaction order in 1 is 0.74, signifying reversible formation of a pre-reaction complex 1 2 2 2 ·ethylene.

n-π Interactions in homoallylic methyl ethers a photoelectron spectroscopic study

Abstract The He I photoelectron spectra of several monocyclic and bicyclic methoxy compounds have been interpreted in terms of inductive effects and n-π interactions between the π cc molecular orbital and the oxygen lone pair orbital n o . The n-π interactions appear to be small, and are mainly through bond.

Synthesis of silyl, germyl, and stannyl alk-1-ynyl ketones from 2-lithio-2-(trimethylsilylethynyl)-1,3-dioxan

The ketones R–CC–CO–MMe3(M = Si, Ge, Sn; R = SiMe3, But) have been prepared from 1,3-dioxan-2-yl acyl anion equivalents.