Direct synthesis of heteroarylethynes via palladiumcatalyzed coupling of heteroaryl halides with ethynylzinc halides. Its application to an efficient synthesis of a thiophenelactone from chamaemelum nobile
A variety of terminal alkynes containing a heteroaryl group can be directly and selectively synthesized by the Pd-catalyzed coupling of heteroaryl iodides or bromides with ethynylzinc halides. Various compounds of this class containing furan, thiophene, and pyridine have been prepared, and the procedure has been applied to an efficient and selective synthesis of a thiophenelactone from Chamaemelum nobile L.
Negishi, Ei-Ichi,Xu, Caiding,Tan, Ze,Kotora, Martin
p. 209 - 214
(2007/10/03)
An improved procedure for the preparation of aryl- and hetarylacetylenes
A number of relatively volatile acetylenes RC ≡ CH (R = aryl or hetaryl) have been prepared with high yields by heating a mixture of the corresponding alcohols RC ≡ CC(CH3)2OH and paraffin oil with small amounts of powdered potassium hydroxide in vacuum. The alcohols were obtained by Pd/Cu-catalyzed cross coupling of aryl or hetaryl halides RX (X = Br, in one case I) with the commercially available HC ≡ CC(CH3)2OH.
Mal'Kina,Brandsma,Vasilevsky,Trofimov
p. 589 - 590
(2007/10/03)
Unusually sluggish copper(I)catalyzed oxidative dimerization of 2-ethynyl-1-methylpyrrole
Reaction of 2-ethynyl-1-methylpyrrole with oxygen in the presence of catalytic amounts of copper(I)chloride proceeds only upon addition of 1,8-diazabicycloundec-7-ene (DBU).
Vasilevsky, S. F.,Verkruijsse, H. D.,Brandsma, L.
p. 529 - 530
(2007/10/02)
UNE NOUVELLE PREPARATION DU FLUOROACETYLENE - SA REACTION AVEC LES ORGANOMETALLIQUES. SYNTHESE D'ALCINES ET D'ENYNES DIVERS
FC*CH has been prepared from 1,1-difluoroethylene at low temperature.Its reaction with various organometallics opens a way to acetylenes bearing tertiary alkyl-, vinyl-, aryl- or heteroaryl groups directly α to the unsaturation.
Sauvetre, R.,Normant, J.F.
p. 4325 - 4328
(2007/10/02)
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