Homologation methylene

On oxidation, the above foimal is com-eitcd to the methylene ether-estei of 5-nitrosalicvlic aeid. Homologous methylene ethers or formats are abro obtained A ith numerous nitrophenols, includuig o-nitro-p-cre.sol and 4-nitio-2-naphthoP . 

In fact, this procedure can be used for any aliphatic series such as alcohols, amines, etc. Consequently, before dealing with a specific homologous series, the validity of using the methylene group as the reference group needs to be established. The source of retention data that will be used to demonstrate this procedure is that published by Martire and his group [5-10] at Georgetown University and are included in the thesis of many of his students. The stationary phases used were all n-alkanes and there was extensive data available from the stationary phase n-octadecane. The specific data included the specific retention volumes of the different solutes at 0°C (V r(To)) thus, (V r(T)) was calculated for any temperature (Ti) as follows. 

A valuable extension of the diazomethane reaction for the preparation of A-homosteroids was discovered by Johnson, Neeman and Birkeland " who found that a,j5-unsaturated ketones are homologated by reaction with diazomethane in the presence of either fluoroboric acid or boron trifluoride. The main product is formed by the insertion of a methylene group between the carbonyl group and the unsaturated a-carbon to give a / ,y-unsaturated ketone. 

D. 1-Methoxy Group as a Eormaldehyde Synthon Methylene Homologation. 115... 

Wilkinson s catalyst 117,345,777 Wittig condensation 73 Wittig homologation 503 Wittig methylenation 649 Wittig reaction 17, 68 f., 86 f.,... 

The reduction of the surface tension between water and heptane brought about by homologous alkanesulfonates and by some disulfonates is demonstrated in Fig. 25 [39]. On comparing Figs. 24 and 25 it is obvious that the adsorption energy of a methylene group at the water-oil interface is greater than at the water-air interface. 

Chloro-2-[l,4-dimethyl(thiosemicarbazido)]quinoxaline 4-oxide (250) with dimethyl acetylenedicarboxylate gave 6-chloro-2-[A-(5-methoxycarbonyl-methylene-3-methyl-4-oxo-2-thioxoimidazolidin-l-yl)-A-methylammo]quinoxa-line 4-oxide (251) (EtOH, reflux, 5 h 54%) a homolog likewise." ... 

Homologs of yS-peptides with one additional methylene group inserted into the backbone of each residue, namely y-peptides (Fig. 2.33), also form well-defined... 

The effect of different backbones on ero.sion rates was demonstrated in a study of the homologous poly[ (p-carboxyphenoxy)alkane] series. As the number of methylene groups in the backbone increased from 1 to 6, thus decreasing the reactivity of the anhydride linkage and rendering the polymer more hydrophobic, the erosion rates underwent a decrease of three orders of magnitude (4). 

The reaction of olefins with dihalogenomethanes to form homologs with one additional carbon atom has been included in the list (no. 37) of reactions in Table I because CH2X2 should form a carbenoid methylene-nickel bond able to give a metallacycle with the olefin, followed by hydrogen transfer. 

In view of the activity of 13, but the lack of activity for the alpha-ethyl homolog of DOM, the two isomeric ring-methylated derivatives Structures 16a and 16b were recently prepared (114). Neither isomer showed significant activity, either as an agonist in the rat fundus preparation or in a mouse assay, when compared with 13. It would appear that little bulk can be tolerated near the alpha-carbon, other than a methyl or methylene. 

Lengthening of the side chain of DMT by a single methylene group produces N,N-dimethylhomotryptamine (DMHT 76, R = H, n = 3), which produced hyperthermia when administered to rabbits (7,232) but was found to be inactive in man (235). Intravenous administration of 5 and 10 mg and intramuscular injection of 20 to 70 mg DMHT was without psychologic effect in 10 human subjects (235). Additional studies on DMHT homologs (i.e., 76, n = 4-10) did not show any interesting activity (7,232). 

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