Tris rhodium chloride esters

A mixture of the a/J-unsaturated ester (14mmol), t-butyldimethylsilane (18 mmol) and tris(triphenylphosphine)rhodium(i) chloride (0.56 mmol) was placed in a pre-heated (100°C) oil bath, and the course of reaction monitored by i.r. spectroscopy. On completion (ca. 30 min) the product was isolated by direct distillation (60-88%). 

Several syntheses are available to the 13,14-dihydroprostaglandins, some of which are metabolites of the E and F series. The first of these routes [143, 144] started from the formyl derivative (LVII) of the enol ether of cyclo-pentan-l,3-dione which on reaction with ethyl 6-bromosorbate and tri-phenylphosphine followed by selective catalytic reduction afforded the ester (LVIII). A second formylation followed by elaboration with n-hexanoyl-methylenetriphenylphosphonium chloride 1 to the ketone (LIX) which on reduction of the exocyclic double bond and acid-catalysed solvolysis in benzyl alcohol afforded the benzyl ether (LX) and its isomeric enol ether. Reduction with lithium tri-t-butoxyaluminium hydride to the corresponding 15-hydroxy-compound and palladium-charcoal catalysed hydrogenolysis followed by prolonged catalytic hydrogenation with rhodium-charcoal led to ( )-dihydro-PGEi ethyl ester. 

The hydrogenation of various a/3-unsaturated acids in the presence of rhodium-phosphine complex catalysts whose ligands are chiral at both phosphorus and carbon gives saturated carboxylic acids with enantiomeric excesses up to 70%. The addition of carbon tetrachloride, catalysed by copper(ll) chloride, to (—)-men thy 1 acrylic and methacrylic esters, followed by hydrolysis, results in /3-tri-chloromethyl derivatives (6) having ca. 50% enantiomeric enrichment at the a-position. ... 

In addition to the methods described above, prenol (51) can be prepared from methyl-butynol (43) by rearrangement to prenal (52) using a titanium alkoxide/copper chloride catalyst [69, 70] followed by selective hydrogenation using a ruthenium rhodium tris( 7-sulfonatoyl)phosphine trisodium salt (TPPTS) catalyst [71, 72]. However, it is more usual to prepare the prenyl esters by nucleophilic substitution of a carboxylate anion on prenyl chloride [503-60-6] (56) which, in turn, is available through hydrochlorination of isoprene [78-79-5] (1). This hydrochlorination often employs copper ions as catalysts. These processes are shown in Fig. 8.14. 

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