Stereoselective Synthesis of Tetrasubstituted (Z)-Alkenes from Aryl Alkyl Ketones Utilizing the Horner-Wadsworth-Emmons Reaction.

Abstract

Tetrasubstituted (Z )-alkenes were readily prepared through the Horner-Wadsworth-Emmons reactions of methyl 2-[bis(2,2,2-trifluoroethyl)phosphono]propionate with aryl alkyl ketones by employing Sn(OSO 2 CF 3 ) 2 and N-ethylpiperidine.

An Efficient Procedure Based on a MW-Assisted Horner–Wadsworth-Emmons Reaction for the Synthesis of (Z)-3,3-Trisubstituted-a,b-unsaturated Esters

“…The first step of our work consisted in comparing conventional and microwave assisted synthesis of 3,3-trisubstituted-α,β-unsaturated methyl esters 1 . The procedure of Sano and co-workers was initially adopted employing bis(2,2,2-trifluoroethyl)(methoxycarbonylmethyl)-phosphonate ( 5 ) combined with stannous trifluoromethanesulfonate [(CF 3 SO 3 ) 2 Sn] and N -ethylpiperidine in anhydrous dichloro-methane (DCM) [ 5 ]. The experimental conditions required two reaction steps, low temperatures and long reaction times.…”

“…The ( E )- or ( Z )- geometrical selectivity of HWE olefination of aldehydes has been extensively studied under conventional conditions [ 3 ] and only recently under microwave irradiation [ 4 ]. Only a few papers on HWE olefination of ketones have been described under conventional conditions [ 5 ] and, to the best of our knowledge, the effect of microwave heating has never been studied.…”

The Wittig Reaction

“…The synthesis of tetrasubstituted alkenes using the HWE reaction generally proceeds with moderate selectivity [33,34]. …”

Visible-Light Photocatalytic E to Z Isomerization of Activated Olefins and Its Application for the Syntheses of Coumarins

“…The synthesis of alkene, especially alkene with specific geometry, had been the area of many efforts since the early era of organic chemistry, and is still the field of invention for modern organic synthesis. Over the decades, many methods have been established to obtain the thermodynamically more stable E-alkenes, however the reliable approaches to access the less stable Z-alkene are far less common [9][10][11][12]. For example, traditional Wittig reaction with unstable yield [13], alkyne hydrogenation, silicon-based stereospecific elimination and contemporary cross-coupling reaction [14], and cross-metathesis [15] are among a few methods which have so far enjoyed widespread applications, due to their simplicity, convenience, and relatively high geometrical control.…”