Alkylation trans

Rhodium forms a-bonded alkyl, trans- Rhl(CNCR])fiU ] [45151-89-1] [Rhl2(P(C2H2)3)2CH3] [47829-28-7]- aryl, [Rh(P(CH3)3)3C2H2]... 

Treatment of the piperidine 74, obtainable from an aminonitrile such as 73, under N-methylation conditions leads to the dimethylamino derivative 75. The carbobenzoxy protecting group is then removed by catalytic hydrogenation. Reaction of the resulting secondary amine 76 with cyclohexene oxide leads to the alkylated trans aminoalcohol. There is thus obtained the anti-arrhythmic agent transcainide (77) [18]. 

Baker s yeast catalyzed the regioselective cycloaddition of stable aromatic nitrile oxides ArCNO [Ar = 2,6-C12C6H3, 2,4,6-Me3C6H2, 2,4,6-(MeO)3C6H2] to ethyl cinnamate, ethyl 3-(p-tolyl)acrylate, and tert-butyl cinnamates (218). Reactions of dichloro- and trimethoxybenzonitrile oxides with all three esters proceeded regio- and stereoselectively to form exclusively alkyl tran.v -3,5-diary 1 -... 

The unusual superacidic properties of trichlorogermane are clearly manifested in its reactions with aromatic compounds. Here, the hydrogermylation of the aromatic nucleus is the basic pathway of the reaction between trichlorogermane and aromatic compounds. In many cases the reaction is accompanied by processes of protodegermylation, alkylation, trans-cis isomerization of the trichlorogermyl derivatives of cyclohexane and formation of some organic salts with GeCl3 counterion. 

This is the sort of selectivity evident in the next example, which looks more complicated but is really just addition of an arylcopper reagent followed by alkylation (trans to the bulky Ar group) with an iodoester. 

This synthesis involves some stereochemistry. Biotin carries the alkyl chain next to sulfur on the more hindered endo face of the molecule, and any successful synthesis has to address this particular problem. Here, the chemists decided to use the fact that alkylations of cyclic sulfoxides result in tram stereochemistry between the new alkyl group and the sulfoxide oxygen atom. As expected, oxidation of the sulfide proceeded faster from the exo face, giving an 8 1 ratio of exoiendo sulfoxides. Alkylation trans to the exo oxygen gave the desired (endo) product. 

The reaction was proposed to include an intramolecular nucleophilic attack of the oxygen atom present in the 2-hydroxyalkyl fragment at the Pt - bound carbon. The reaction involves an isomerization of a less reactive dpms complex 21 to a more reactive isomeric 22 with the alkyl trans- to the sulfonate. 

Insertion of olefins into the Pt—H bond of square-planar hydrides /ra 5-[(Pt(H)-(X)(L)a] was originally assumed to involve olefin co-ordination to give a five-coordinate intermediate which underwent migratory rearrangement to the alkyl trans-[Pt(R)(X)(L)a]. Recent MO calculations of the insertion reaction between ethylene and [Pt(H)(Cl)(PH3)a] suggest that collapse of the five-co-ordinate intermediate is... 

PRILESHAJEVA, N., and A. Terenin Free radicals in the photo-dissociation of gaseous methyl alkyls. Trans. Faraday Soc. 31, 1483 (1935). 

A reaction has been developed for the conversion of a 3-unsaturated ketones into 3-alkyl trans-1,2-diols. Previously it had been shown that addition of MejCuLi to cyclohex-2-enone followed by acid workup gives 3-methyl-cyclohexanone in high yidd. If, after Me2CuLi addition and separation from the black copper-containing precipitate, the reaction mixture is treated with borane, followed by oxidation with alkaline HjOj, a 55% yield of two diols (108) and (109) in a ratio of 87 13 is obtained. Likewise, isophorone (110) was converted into (111) after a two-day hydroboration step in 53% yield. 

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