Stannyl carboxylates

We can also find examples of fragmentation of cation radicals in photochemical reactions (see section a-Keto Radicals from a-Stannyl Carboxylates ). Here, one example is presented illustrating the cleavage of cation radical CR13 of dimethyl(trimethylsilyl-methyl)amine (13) in a photochemical reaction described by Mariano and co-workers (Scheme 8). ... 

Acyltins. Acyltins, which are sensitive toward oxygen giving stannyl carboxylate, can be coupled with acid chlorides to yield a-diketones.f A CO atmosphere suppresses decarbonylation which is the major side process. 

The reaction of bis-silyl- or stannylcarbodiimides 41 with carboxylic acid halides or anhydrides,affords carbonylcarbodiimides 42 having one silyl or stannyl substituent. 

Stannyl- (and -silyl-) carboxylic acids undergo oxidative decarboxylation with LTA under mild conditions to provide the corresponding alkenes. This represents an improvement on the well-known alkene-forming decarboxylation of acids with LTA, which requires thermtd or photochemical conditions, for example. The directing metal effect leads to improved yields and regioselectivity. However, stereo-specific alkene formation did not occur and this could imply free radical involvement or transmetallation (Pb for Sn) (stereochemistry ) followed by cation formation, see for example Scheme 27. 

J2J2j6 -Stannyl Hydrazones, Oximes and Carboxylic Acids... 

The method of Liebeskind <1996JA2748> was adapted for the coupling of 6-iodopterins 203 with the stannylated l,3-dithiol-2-one 204 in the presence of copper thiophene-2-carboxylate to produce pteridine derivatives 205 and 206 containing the l,3-dithiol-2-one unit (Equation 10) <1998T9559, 2001J(P1)3239>. 

The acyltrialkylstannanes are readily hydrolysed to the parent aldehydes, and are oxidised in the air to give the corresponding carboxylates, R3SnOCOR 63 in a radical chain reaction which presumably is similar to that of the autoxidation of an aldehyde, and involves as a key step the Sh2 reaction of an acylperoxyl radical at tin rather that at hydrogen (equation 6-26). The trialkylstannyl peroxyester which is formed then reacts with the parent stannyl ketone to give the trialkyltin carboxylate. 

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