Silanes Trimethylsilyldiazomethane

The scope of the multi-residue method is extended permanently by testing and then including further active substances that can be determined by GC. Acidic analytes (such as phenoxyacetic acids or RCOOH metabolites) are included into the homogeneous partitioning by acidifying the raw extracts to a pH below the pKs value of the carboxylic acids. To include these analytes in the GC determination scheme they have to be derivatized with diazomethane, diazoethane, trimethylsilyldiazomethane, acidic esterification or benzylation, or by silanizing the COOH moiety. 

An example of an iron-catalyzed C-C bond formation reaction was reported in 2001 [89]. Treatment of propargyl sulfides 87 with trimethylsilyldiazomethane in the presence of 5 mol% FeCl2(dppb) gave substituted homoallenylsilanes 88 in good to moderate yields (Scheme 3.43). The silanes 88d and 88e, which bear two centers of chirality, were obtained as 1 1 mixtures of diastereomers. Slight diastereoselectivity (2 1) was seen for the formation 88f, which is an axially chiral allene with a sterogenic center. 

The concentration of trimethylsilyldiazo-methane in hexane can be determined by adding 91mg (0.5mmol) of dibenzyl (see [103-29-7], Aromatic compounds) in 1ml of the hexane solution containing it, and measuring the H NMR. The concentration of the azo-silane (x mmol/ml) is calculated from the formula x = 2a b, where a is the integral value (mm) of the methine proton (5 2.58) of trimethylsilyldiazomethane, and b is the integral value (mm) of the methylene protons (5 2.99) of dibenzyl. [Shioiri Aoyama Org Synth Coll Vol Vin 612 1993, Mori et al. Chem Pharm Bull Jpn 30 3380 1982],... 

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