P. E. Van Rijn

An efficient method for the conversion of 2-alkynyl ethers into allenic ethers and some α-substituted derivatives

Summary Reaction of 2-alkynyl ethers RC=CCH 2 OR′ with butyllithium and potassium t-butoxide in THF, followed by addition of HMPT, gives the α-metal-lated allenic ethers RCH=C=C(M)OR′ (M is probably K). Subsequent addition of water, alkyl halide, or trimethylchlorosilane affords the allenic ethers RCH=C=CHOR′ and their derivatives RCH=C=C(R″)OR′ or RCH=C=C(SiMe 3 )-OR′, respectively.

Preparation of 1-dialkylamino-1,2,3-trienes, a novel type of cumulenes

Abstract Solutions of α-lithiated cumulenic amines are produced upon treatment of l-dialkylamino-4-methoxy-4-methyl-2-pentynes with two equivalents of butyllithium. Subsequent protonation with t-butyl alcohol gives the corresponding cumulenic amines, while treatment with trimethylchlorosilane gives the α-trimethylsilylated derivatives.

Synthesis and characterization of some ω-dimethylamino-1-alkynylzing compounds

Abstract Ethyl (ω-dimethylamino-1 -alkynyl)zinc compounds and bis (ω-dimethylamino-l-alkynyl)zinc compounds were prepared by metalation of the dimethyl amino alkynes HCC(CH 2 ) n ,NMe 2 ( n = 1–4) with diethylzinc and diphenylzinc. All compounds show oligomeric or polymeric association in benzene, the degree of association being dependent on the value of n . The presence of coordinating dimethylamino groups and/or bridging alkynyl groups was established by IR and NMR spectroscopy. Plausible structures for all compounds, based on spectroscopic and molecular weight data, are presented.

1-Alkynylzinc compounds derived from 1-dimethylamino-3-butyne

Abstract Ethyl(4-dimethylamino-1-butynyl)zinc was prepared by metalation of 1-dimethylamino-3-butyne with diethylzinc in benzene. Bis(4-dimethylamino-1-butynyl)zinc was synthesized similarly from diphenylzinc and two equivalents of the acetylenic amine. Both compounds are trimeric in benzene; structures are proposed on the basis of the spectroscopic evidence.