An easy one-pot synthesis of group 14 C-metallated 2 (or 3)-furan- and thiophenecarbaldehydes
The group 14 C-metallated 2(or 3)-furan- and thiophenecarbaldehydes 4-19 have been regioselectively prepared by a one-pot procedure from the corresponding furan- and thiophenecarbaldehydes using lithium N-methylpiperazide/butyllithium or sec-butyllithium/chlorotrialkylsilanes (germanes, tin)/water as sequence of reagents.
Gold catalysis contra platinum catalysis in hydroarylation contra phenol synthesis
Three silylated γ-alkynylfurans were prepared and subjected to both gold and platinum catalysts. The TMS- and the TBDMS-substituted furans reacted. With AuCl3 and the binuclear [(Ph3PAu)2Cl][BF4] catalyst a hydroarylation of the alkyne was observed. Na[AuCl4] gave phenols as the product, but these were formed only after in situ desilylation of the starting material by the gold catalyst and thus the wrong isomer dominated. Only with PtCl2(MeCN)2 phenols with a silyl group were formed. The TBDPS-substituted furan failed to react. Two alkynylsilanes were synthesized, but they also failed to react.
Hashmi, A. Stephen K.,Kurpejovi?, Elzen,Frey, Wolfgang,Bats, Jan W.
p. 5879 - 5885
(2008/02/02)
ENANTIOSELECTIVE SYNTHESIS OF FURYLALCOHOLS BY CATALYTIC ASYMMETRIC ADDITION OF DIETHYLZINC TO FURANALDEHYDES
Optically active 2-furylcarbinols with up to 97percent enantiometric excess were prepared by highly ?-face selective addition of diethylzinc to furan aldehydes catalyzed by aminoalcohol ligands 3 to 6.
Oeveren, Arjan van,Menge, Wiro,Feringa, Ben L.
p. 6427 - 6430
(2007/10/02)
HETEROORGANIC FURAN DERIVATIVES. 61. TRIMETHYL(5-METHYL-2-FURYL)SILANE AND TRIMETHYL(5-METHYL-2-FURYL)GERMANE
The transformations of trimethyl(5-methyl-2-furyl)silane and trimethyl(5-methyl-2-furyl)germane were studied upon vapor-phase oxidation by atmospheric oxygen on a V-Mo-Ag-O catalyst.Under these conditions, trimethyl(5-formyl-2-furyl)silane and trimethyl(5-formyl-2-furyl)germane are formed albeit in only 5-7percent yield.This low yield is a consequence of the thermal instability of the starting compounds and the aldehydes formed.The oxidation of 2-methyl-5-tert-butylfuran was studied under comparable conditions.The corresponding aldehyde was obtained in 30percent yield.A scheme was proposed for the catalytic oxidation of 5-substituted 2-methylfurans.
Lukevits, E.,Ignatovich, L. M.,Iovel', I. G.,Gol'dberg, Yu. Sh.,Shimanskaya, M. V.
p. 15 - 17
(2007/10/02)
CHEMOSELECTIVE PROTECTION OF HETEROAROMATIC ALDEHYDES AS IMIDAZOLIDINE DERIVATIVES. PREPARATION OF 5-SUBSTITUTED FURAN- AND TIOPHENE-2-CARBOXALDEHYDES VIA METALLO-IMIDAZOLIDINE INTERMEDIATES
Furan-, tiophene- and N-methylpyrrole-2-carboxaldehydes may be transformed into the corresponding N,N'-dimethylimidazolidines in a reaction not requiring acid catalysis.The resulting furan and tiophene (but not N-methylpyrrole) derivatives may be metallated in high yields and the carboxaldehyde functionality regenerated under very mild conditions.Treatment of the aldehydoketone 2-acetyl-5-formylthiophene with N,N'-dimethylethylenediamine gives only the product of reaction at the aldehyde function thus establishing this methodology as a potentially valuable method for the protection of an aldehyde in the presence of a ketone.
Carpenter, Andrew J,,Chadwick, Derek J.
p. 3803 - 3812
(2007/10/02)
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