General and Highly Efficient Synthesis of 2-Alkylideneazetidines and β-Lactams via Copper-Catalyzed Intramolecular N-Vinylation
摘要:
[GRAPHICS]N-Tosyl-3-halo-3-butenylamines underwent efficient Ullmann-type coupling with the catalysis of Cul/N/N'-dimethylethylenediamine to afford 2-alkylideneazetidines, which could be readily converted to the corresponding, beta-lactams by oxidation with O-3.
The present invention provides a process for producing a propargylcarbinol compound of formula (I): ##STR1## where R.sup.1 and R.sup.2 are as defined herein. The process comprises reacting a haloallycarbinol compound of formula (II) with a base. The present invention also relates to a process for producing the haloallylcarbinol compound. The above propargylcarbinol compound is useful as an intermediate for agrochemicals, pharmaceuticals, perfumes, resin monomers, and the like.
to produce unisolable allylchromium species which add efficiently to aldehydes or ketones with high degree of stereo- and chemoselectivity. Particularly, high threo selectivity is observed in the reaction of aldehydes and 1-bromo-2-butene and is ascribed to a chair-like six-membered transition state. Simple reduction of allylic and benzylic halides produces biallyls and bibenzyls, while gem-dibromocyclopropanes
Indium-Trichloride Mediated Synthesis of 4,4-Dichlorotetrahydropyrans
作者:Jun Yang、Chao-Jun Li
DOI:10.1055/s-1999-2707
日期:1999.6
The cross-coupling of aldehydes with chloro homoallyl alcohols mediated by indium trichloride generated (cis) 2,6-disubstituted-4,4-(gem)-dichlorotetrahydropyrans smoothly with high diastereoselectivity.
A new variation of Prins cyclization to directly and stereoselectively synthesize cis-2,6-disubstituted tetrahydropyran-4-ones from 3-chlorohomoallylic alcohols and aldehydes catalyzed by perrhenic acid is reported. The reaction is generally compatible with a range of aliphatic and aromatic aldehydes and 24 examples of tetrahydropyran-4-one products have been prepared in moderate to good yields. This