Olefination aldehydes

Electrolysis, Bu4N Br, H2O, CH3CN, NaHC03- This method is unsatisfactory for primary and secondary alcohols, aldehydes, olefins, or amines. 

ALDEHYDES FROM PRIMARY ALCOHOLS BY OXIDATION WITH CHROMIUM TRIOXIDE 1-HEPTANAL, 52, 5 ALDEHYDES FROM sym-TRITHIANE n-PENTADECANAL, 51, 39 Aldehydes, acetylenic, 54, 45 Aldehydes, aromatic, 54, 45 Aldehydes, benzyl, 54, 45 Aldehydes, olefinic, 54, 45... 

The resulting material contains 1.25 wt % Re. As it is not stable in the presence of H2O2, it could not be used for olefin epoxidation. Instead, it was tested for aldehyde olefination reactions [62] (Scheme 17). The catalytic activity is lower than that observed for the homogeneous process but is retained even after three catalytic runs. 

Numerous useful transition metal-catalyzed reactions of organic halides are now known. Practical syntheses of esters, acids, amides, aldehydes, olefins, ketones, and acetylenes have been described. In many instances the metal-catalyzed reactions are superior to more conventional, purely organic routes to the same compounds. 

Reaction conditions 5 imol [Rh(CO)2(acac)], P/Rh = 6, 30 bar CO/H2 (1 1), 100 °C for 1-decene and 1-hexadecane, 80 °C for styrene and n-butyl acrylate, hexane/toluene/perfluoromethylcyclohexane = 4/2/4 (mL), 15 h reaction time. The products were analysed by H NMR and the conversion and selectivity confirmed by GC. To aldehyde, olefin isomerisation accounts for the product balance. c Linear to branched aldehyde ratio, determined by HNMR. The branched product was a 1 1 mixture of enol and aldehyde, the linear aldehyde was < 1%. 

F. E. Kuhn, A. Scherbaum, and W. A. Flerrmann, Methyltrioxorhenium and Its Applications in Olefin Oxidation, Metathesis and Aldehyde Olefination, J. Organomet. Chem. 689, 4149-4164 (2004). 

Diels-Alder additions in water. It also catalyzes aldehyde olefination with N2C(C02Et)2 and PPhs as oxygen sink. Its catalyzed decomposition of N2C(C02Et)2 leads to carbene transfer reactions allowing for the formation of epoxides from aldehydes and ketones, aziridines from imines and cyclopropanation. 

Olefinations involving phosphonate anions continue to be used and developed. The effect of the cation, temperature and THF or DME as solvent on the stereoselectivity of aliphatic aldehyde olefination with trimethyl phosphonoacetate carbanion has been investigated.71 Low ( /Z) ratios are favoured by potassium cations, low temperature and THF as solvent. The... 

As alternatives to nucleophilic additions to C6 or C5 aldehydes, olefinations of the same compounds offer a repertoire of solutions to chain extensions or to the coupling of two carbohydrate building blocks. As shown in the above section, chain extensions at C6 are often followed by the introduction of new functional groups and thus new chiral centers. In this regard, olefins obtained via Wittig-type reactions are excellent starting compounds. 

SCHEME 13.51 Schreiber s synthesis of (—)-hikizimycin featuring a two-directional chain-elongation strategy involving an aldehyde olefination and face-selective dihydroxylations. 

During the reaction mainly dimers accumulate on e catalyst but we have also found aromates, ketones, aldehydes, olefines and alkanes in extraction and in temperature programmed desorption. 

Specialty chemicals are being produced from inexpensive aldehyde/olefin feedstocks, independently of natural products. 

Cyclization of aldehyde olefin 94 was also investigated, and was found to lead to a 1 1 mixture of bridged products 99 and 100 (Scheme 18). This transformation probably occurs through sulfonyl imine Lewis acid complexes cyclizing via conformations 95 and 96 to carbonium ions 98 and 97, respectively. Proton elimination from these intermediates would afford the observed epimeric sulfonamide alkenes. 

An unsuccessful attempt was made to apply this methodology to a total synthesis of the Ergot alkaloid lysergic acid (Scheme 19) [42]. Therefore, aldehyde olefin 107 was prepared and was exposed to the Kresze conditions with the... 

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