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ATRP Synthesis of poly(4-bromostyrene)-b …

With theoptimized conditions determined, we next turned our attentionto the scope of the dehydrogenative borylation reaction (Scheme ). The reaction with the parent styrene furnished 3b in 77% yield. While the electron-rich p-methoxystyrene was a suitable substrate for the reaction (3a, 86% yield), p-(dimethylamino)styreneproduced the corresponding BN stilbene 3c in moderate56% yield. Steric influences on styrene do not appear to affect theyield of BN stilbene products as both p- and o-tolylstyrene are suitable substrates (3d and 3e). Electron-withdrawing substituents are tolerated (3f, 3g, and 3h). Finally, p-bromostyrene couples with 1 to generate aBN stilbene that can be potentially further functionalized throughcross-coupling (3i).

-β-bromostyrene reacts with terminal alkynes with retention of the steric ..

The preparation of l-bromo-2-phenylethylene consists in stereospecific bromination of (E)-cinnamic acid, followed by decarboxylative elimination of the resulting bromoacid; the latter reaction leads to (Z)-p-bromostyrene as practically the only product when it is run in butanone, whereas in water the major product is the E isomer.

Wu, T.; Cai, Y.; Zhao, X.; Ngai, C

A correlation of the glass transition temperatures of the cotelomers with those of pure polybromostyrene and polybutadiene is discussed.

A new palladium(II) complex based on ,-dimethylethanolamine, (-4-1′)-bis[,-dimethylaminoethoxy-k,]palladium(II) which coordinates with two moles of AcOH, has been synthesized. The structure of the complex has been established by X-ray diffraction analysis. Using this complex as a catalyst, a series of conjugated enynes were successfully synthesized by Sonogashira cross-coupling reaction in the absence of co-catalyst CuX and any ligand at room temperature during 20 hours affording the corresponding products in moderate to excellent yields. The optimized catalytic systems are tolerant in the presence of a broad variety of functional groups in the substrates. The catalytic system was found to be ineffective for vinyl chloride. Moreover, it was found that ()-β-bromostyrene reacts with terminal alkynes with retention of the steric configuration and the transformation of most of the -isomer did not occur in this reaction.

A new palladium(II) complex based on ,-dimethylethanolamine, (-4-1′)-bis[,-dimethylaminoethoxy-k,]palladium(II) which coordinates with two moles of AcOH, has been synthesized. The structure of the complex has been established by X-ray diffraction analysis. Using this complex as a catalyst, a series of conjugated enynes were successfully synthesized by Sonogashira cross-coupling reaction in the absence of co-catalyst CuX and any ligand at room temperature during 20 hours affording the corresponding products in moderate to excellent yields. The optimized catalytic systems are tolerant in the presence of a broad variety of functional groups in the substrates. The catalytic system was found to be ineffective for vinyl chloride. Moreover, it was found that ()-β-bromostyrene reacts with terminal alkynes with retention of the steric configuration and the transformation of most of the -isomer did not occur in this reaction.

K.; Chu, B.; Hsiao, B.; Hadjiargyrou, M.; Grubbs, R

A correlation of the glass transition temperatures of the cotelomers with those of pure polybromostyrene and polybutadiene is discussed.

Thefirst example of catalytic B–H activation of azaborinesleading to a new family of stilbene derivatives through dehydrogenativeborylation is reported. Ten 1,2-azaborine-based BN isosteres of stilbeneshave been synthesized using this method, including a BN isostere ofa biologically active stilbene. It is demonstrated that BN/CC isosterismin the context of stilbenes can lead to significant changes in theobserved photophysical properties such as higher quantum yield anda larger Stokes shift. Direct comparative analysis of BN stilbene 3g and its carbonaceous counterpart 6g is consistentwith a stronger charge-transfer character of the excited state exhibitedby 3g in which the 1,2-azaborine heterocycle serves asa better electron donor than the corresponding arene.

A retrosynthetic analysis revealed that B–H activationof1,2-azaborines coupled with C–H activation of styrenes throughdehydrogenative borylation could furnish the desired 1,2-azaborine-basedBN stilbene compounds (Scheme ). The use ofstyrenes as direct coupling partners appears particularly attractivedue to their ready commercial availability. However, despite some recent progress in the late-stage functionalizationof 1,2-azaborines, no systematic studyof the B–H activation chemistry of azaborines has been performed. We reported previously that the B–H bondin 1,2-azaborines is relatively nonhydridic. Indeed, no reaction is observed between our model N-benzyl-B-H-1,2-azaborine 1 and p-methoxystyrene 2 in the absence of promoterseven at elevated temperatures (up to 110 °C). We thus surveyeda number of commercially available catalysts known to promote B–Hactivation and dehydrogenative borylations to facilitate the formation of BN stilbene 3a.

10/08/2008 · Does anyone know how to synthesize ibuprofen from benzene
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