Wittig‐Type Olefination of Alcohols Promoted by Nickel Nanoparticles: Synthesis of Polymethoxylated and Polyhydroxylated Stilbenes

Abstract

Nickel nanoparticles were found to promote the Wittig‐type olefination of primary alcohols with phosphorus ylides. The latter can be prepared from the corresponding phosphonium salts with nBuLi or in situ generated with lithium metal. The methodology is especially efficient for the synthesis of stilbenes and is applied in the absence of any additive as ahydrogen acceptor. A new approach to the synthesis of polymethoxylated and polyhydroxylated stilbenes, including resveratrol, DMU‐212 and analogues, is presented.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Tandem-, Domino- and One-Pot Reactions Involving Wittig- and Horner-Wadsworth-Emmons Olefination

“…One-pot oxidation-Wittig olefination reactions are also quite common [40,, especially when the carbonyl component is labile [89,97]. Often, the oxidant of choice is MnO 2 [40,[43][44][45][46][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96][97], although a number of reactions are known where transformations were carried with air oxygen using metals and metal oxides as catalysts [72][73][74][75][76][77][78]. As many Wittig-and HWE reactions tolerate metal catalysts, this allows the running of Wittig/HWE reactions in combination with metal catalyzed cross coupling reactions and olefinations such as Heck [114][115][116][117][118][119][120][121][122][123], Suzuki [111]…”

“…As oxidants, activated MnO 2 [43][44][45][46], barium permanganate [47,48], tetra-n-propylammonium perruthenate (TPAP)/N-methylmorpholine N-oxide (NMO) [49][50][51][52][53][54] and TPAP/N,N,N′,N′-tetramethylenediamine dioxide (TMEDAO 2 ) [55], o-iodoxybenzoic acid (IBX) [56][57][58], Dess-Martin periodinane [59][60][61], DMSO-oxalyl chloride (Swern conditions) [62][63][64], DMSO-SO 3 -pyridine (Parikh-Doering oxidation) [38,39] or DMSO-SO 3 -triethylamine [65], pyridinium chlorochromate (PCC) or PCC/celite [66][67][68][69] as well as pyridinium dichromate (PDC) [70] such as PDC encapsulated in sol gel [71] (27) [72], nanoparticulate ruthenium supported on highly porous aluminum oxyhydroxide [73] or on silica gel [74], and nickel nanoparticles [75,76] Tandem-, Domino-and One-Pot Reactions Involving Wittig-and Horner-Wadsworth-Emmons... http://dx.doi.org/10.5772/intechopen.70364using activated MnO 2 [79]. Over the years, this process has been used more often [40,[80][81][82]…”

Attempt to Synthesize 2,3,5,4′-Tetrahydroxystilbene Derived from 2,3,5,4′-Tetrahydroxystilbene-2-<i>O</i>-β-glucoside (THSG)

“…4-Methoxybenzyltriphenylphosphonium bromide was synthesized from 4-methoxybenzylalcohol by bromination, followed by reaction with triphenylphosphine. 27) The phosphonium salt was reacted with the aldehyde 3 in the presence of 15% NaOH as base and nBu 4 NI to give the desired 2,3,5,4′-tetramethoxystilbene as a mixture of E and Z isomers (Chart 4).…”

Ruthenium nanoparticle-intercalated montmorillonite clay for solvent-free alkene hydrogenation reaction

“…[27] To the best of our knowledge, this is the first solvent free Ru MMT catalyzed Wittig-type reaction of properly substituted benzyl alcohols and phosphorus ylides, in which there is no standard redox step was used and we synthesized dehydrobrittonin A with moderate yield and the process also displayed low diastereoselectivity, mainly in favor of the E diastereoisomer. [28] In our study, a maximum ca. 1:4 Z/E ratio of diastereomeric dehydrobrittonin A was obtained while Nickel nanoparticles offered the same reaction product with comparatively low diastereomeric Z/E ratio (46:54) (Scheme 1).…”