2-alkylchromans, as well as an azachroman derivative. The asymmetric version of this approach via a Noyori-catalyzed ketone reduction and subsequent cyclization is likewise highlighted. A convergent three-step method for the synthesis of 2-substituted chromans is described. These results have been accomplished via the Heck coupling of readily accessible allylic alcohols and 2-iodophenols, followed by reduction and
(C−O) bond in alkyl ethers could simplify chemical syntheses through the elaboration of these robust, readily available precursors. Here we report that dibromoboranes react with alkyl ethers in the presence of a nickel catalyst and zinc reductant to insert boron into the C−O bond. Subsequent reactivity can effect oxygen-to-nitrogen substitution or one-carbon homologation of cyclic ethers and more broadly
The reaction of primary alkyl or vinyl phenylethers (1) as well as 2,3-dihydrobenzofuran (3) with an excess of lithium powder and a catalytic amount of DTBB (5 %) in THF at room temperature leads to the corresponding organolithium intermediates, which by treatment with different electrophiles [H2O, D2O, Me3SiCl, ButCHO, PhCHO, Me2CO, Et2CO, (CH2)4CO, PCH2)5CO, PhCOMe] and final hydrolysis affords
One-Pot Synthesis of O-Heterocycles or Aryl Ketones Using an InCl<sub>3</sub>/Et<sub>3</sub>SiH System by Switching the Solvent
作者:Wenqiang Jia、Qiumu Xi、Tianqi Liu、Minjian Yang、Yonghui Chen、Dali Yin、Xiaojian Wang
DOI:10.1021/acs.joc.9b00140
日期:2019.5.3
An efficient one-pot synthesis of O-heterocycles or aryl ketones has been achieved using Et3SiH in the presence of InCl3 via a sequential ionic hydrogenation reaction by switching the solvent. This methodology can be used to construct C–O bonds and to prepare conjugate reduction products, including chromans, tetrahydrofurans, tetrahydropyrans, dihydroisobenzofurans, dihydrochalcones, and 1,4-diones
An efficient synthesis of flavans from salicylaldehyde and acetophenone derivatives
作者:Ofentse Mazimba、Ishmael B. Masesane、Runner R. Majinda
DOI:10.1016/j.tetlet.2011.09.147
日期:2011.12
An efficient total synthesis of flavans from the reactions of salicylaldehyde and acetophenonederivatives is reported. The synthesis involves preparation of chalcones through an aldol reaction followed by reduction of both the double bond and the ketone using NaBH4 and an acetic acid mediated cyclization. Methoxy groups on the aromatic rings did not affect significantly the yields of the procedure