Lipidic alkyl halides

The fungicidal properties of dithiocarbamates, like thiram, are probably associated with their ability to chelate with essential trace metals such as copper and zinc. Additionally, the 1 1 metal chelates are themselves fungicidal with the ability to penetrate lipid barriers in the fungal cell, and are probably the ultimate toxicants in these fungicides.3 Alkyl esters of dithiocarbamic acids are readily prepared by treatment of sodium dithiocarbamate (4) with the appropriate alkyl halide (Scheme 20). 

Treatment of 5,6-0-isopropylidene-L-ascorbic acid with alkyl halides and NaHCOs in DMSO gave alkylation only at 0-3 the products were then hydrolysed to give 3-0-alkyl-ascorbic acids as free radical scavengers.78 The crown ether type of derivatives (68) of isopropylidene-L-ascorbic acid could be made by interaction with the appropriate ditosylate and K2CO3 in DMF the reaction was unsuccessful in the case of (68, n=2).79 The mechanism by which 3-0-dodecylcarboxymethyl-ascorbic acid inhibits lipid peroxidation. 

For a wide variety of (13 0), (15 0), (17 0) and higher alkyl substituted phenolic lipids a universally applicable method of preparation has been reaction of an OH-protected phenolic aldehyde with an even carbon number n-alkylmagnesium halide, followed by reduction (or dehydration and reduction) and removal of the protective group. This technique has been used with 3-methoxybenzaldehyde, 3,5-dimethoxybenzaldehyde or their isomers and further substituted versions. 

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