A highly efficient [8 + 2] cycloaddition reaction of azaheptafulvenes with α-chloro aliphatic aldehydes enabled by N-heterocyclic carbene catalysis is presented, delivering cis-cycloheptatriene-fused γ-lactams with good yields, moderate to good diastereoselectivies, and excellent enantioselectivies. This higher order cycloaddition reaction can be readily expanded to the gram scale, and the products
Highly diastereoselective synthesis of substituted epichlorohydrins and regioselective preparation of allyl alcohols using chloro or iodomethyllithium
作者:JoséM. Concellón、Luján Llavona、Pablo L. Bernad
DOI:10.1016/0040-4020(95)90943-q
日期:1995.5
Substituted epichlorohydrins 3 or 6 are obtained from α-bromo or α-chlorocarbonyl compounds (1 or 4) and chloro or iodomethyllithium, respectively. Starting from α-bromocarbonyl compounds 1 or acyclic α-chloro ketones the reaction takes place with total diastereoselectivity. Treatment of epichlorohydrins 3 or 6 with lithium iodide affords the same substituted allyl alcohols 7 in a regioselective manner
Synthesis of <i>trans</i>-2-Substituted Cyclopropylamines from α-Chloroaldehydes
作者:Michael S. West、L. Reginald Mills、Tyler R. McDonald、Jessica B. Lee、Deeba Ensan、Sophie A. L. Rousseaux
DOI:10.1021/acs.orglett.9b03172
日期:2019.10.18
report the synthesis of trans-2-substituted cyclopropylamines in high diastereoselectivity from readily available α-chloroaldehydes. The reaction proceeds via trapping of an electrophilic zinc homoenolate with an amine followed by ring closure to generate the cyclopropylamine. We have also observed that cyclopropylamine cis/trans-isomerization occurs in the presence of zinchalidesalts and that this
examples have been reported in the area of asymmetric vicinal dihalogenation of alkenes for accessing dihalogenated products; in this report, an alternative generation method of contiguous halide-bearing stereocenters α,β,γ,δ relative to carbonyl group in excellent enantioselectivity is proposed by utilizing a Song’s oligoEG catalyst-catalyzed asymmetric β-elimination. According to this methodology