Tributyltin hydride-mediated radical cyclisation of aldehydes and unsaturated ketones: the synthesis of hydroxy tetrahydrofurans, chromanols and related compounds
作者:David Bebbington、Jon Bentley、Paul A Nilsson、Andrew F Parsons
DOI:10.1016/s0040-4039(00)01586-0
日期:2000.11
The tributyltin hydride-mediated cyclisation of unsaturated ethers bearing an aldehyde or α,β-unsaturated ketone group is reported. Cyclisation proceeds viaaddition of the tributyltin radical to the carbonyl double bond and the resultant O-stannyl ketyl can add intramolecularly to electron-rich double bonds to form hydroxy tetrahydrofurans, chromanols or related compounds.
Rh-catalyzed asymmetric transfer hydrogenation. This transformation allowed the reduction of both the C═C and C═O bonds and the formation of two stereocenters in high yields with excellent levels of diastereo- and enantioselectivities (up to >99:1 dr, up to >99% ee) in a single step through a dynamic kinetic resolution process using a low catalyst loading and HCO2H/DABCO as the hydrogen source.
通过Rh催化的不对称转移氢化反应,可以直接从(E)-3-亚苄基-苯并二氢吡喃酮中获得对映异构体富集的顺式-3-苄基-苯并二氢苯并二氢苯并二氢吡喃酚。这种转变可以降低C═C和C═O键,并以高收率形成两个立构中心,且非对映和对映选择性极好(高达> 99:1 dr,高达> 99%ee)。通过动态动力学拆分过程的一个步骤,即使用低催化剂负载量和HCO 2 H / DABCO作为氢源。
Tributyltin hydride-mediated radical cyclisation of carbonyls to form functionalised oxygen and nitrogen heterocycles
作者:Jon Bentley、Paul A. Nilsson、Andrew F. Parsons
DOI:10.1039/b202077g
日期:2002.6.7
The tributyltin hydride-mediated cyclisation of unsaturated ethers and aminesbearing an aldehyde or α,β-unsaturated ketone group is reported. Cyclisation proceeds via reversible addition of the tributyltin radical to the carbonyl double bond to form an intermediate O-stannyl ketyl. This nucleophilic radical can add intramolecularly to electron-rich double bonds to form substituted 5- or 6-membered
A general and highly efficient method for asymmetric sequential hydrogenation of α,β-unsaturated ketones has been developed by using an iridium/f-Ampha complex as the catalyst, furnishing corresponding chiral alcohols with two contiguous stereocenters in high yields with excellent diastereo- and enantioselectivities (up to 99% yield, >20 : 1 dr and >99% ee). Control experiments indicated that the CC
通过使用铱/f-Ampha 配合物作为催化剂,开发了一种通用且高效的 α,β-不饱和酮的不对称顺序氢化方法,以高收率提供具有两个连续立体中心的相应手性醇,并具有优异的非对映和对映选择性(高达 99% 的产率,>20 : 1 dr 和 >99% ee)。对照实验表明,烯酮的 C C 和 C O 键依次氢化,最终的立体选择性由酮的动态动力学拆分决定。此外,DFT 计算表明,外球途径参与了 C C 和 C的减少。O 烯酮键。该方法的合成效用通过克级反应和极低催化剂负载量 (S/C = 20 000) 和获得抗哮喘药物 CP-199,330 的关键手性中间体的简明合成路线得到证明。
Reductions par les hydrures et hydroboration etude de la stereoselectivite de nouvelles voies d'acces aux 3-arylmethyl-4-chromanols (Homoisoflavanols)
作者:Michel Gomis、B. Serge Kirkiacharian
DOI:10.1016/s0040-4020(01)89754-4
日期:1990.1
The reduction of 3-arylmethyl-4-chromanones by sodium borohydride, lithium tri-tert-butoxyaluminum hydride and hydroboration followed by oxydation of 3-benzyl-4-hydroxy-coumarines lead to mixtures of Cis and Trans diastereoisomers of 3-arylmethyl-4-chromanols (homoisoflavanols). The reduction of 3-arylmethyl-4-chroma- nones by diborane or bis-tert-butylthioethane diborane (BTED) is stereoselective