Organotin compounds reactions with carbonyls

Various organotin reagents react with acyl and aroyl halides under mild conditions without decarbonylation to give carbonyl compounds[390,39l]. Alkyl- or alkenyltin reagents react with acyl and aroyl chlorides to give ketones[548.733,734]. One example is the preparation of the a,/3-dnsaturated 7-keto esters 860 and 861, carried out under a CO atmosphere[735]. The reaction has been applied intramolecularly to the synthesis of the macrocyclic keto... 

By reaction with the appropropriate aryl halides can be prepared a variety of aryltin compounds that are not accessible from the reactions involving arylmagnesium halides and organotin halides (88,89) there is evidence that an aryne intermediate may be involved (90). However, for some purposes, such as the addition to carbonyl compounds, ox-iranes, and oxetanes, to give hydroxyalkyltin compounds, the Sn-Mg reagents may have advantages (see Section II,E) (91-93). 

The stannylenes from either source will insert into the Sn- Sn, Sn-R, or Sn-H bonds of organotin compounds, and react with alkyl halides, disulfides, or peroxides as shown in the reaction scheme below, but only the stannylenes that are generated photolytically will react with carbonyl compounds, and it appears that the stannylenes may exist in two forms, perhaps related as singlet and triplet, or a com-plexed and uncomplexed species. 

In 1979 the reaction of benzyl and aryl halides was reported with mechanistic discussions [8, 9]. The first palladium-catalyzed carbonylative coupling of organic halides with organotin compounds was reported by Tanaka in the same year (Scheme 4) [10,11]. 

Alkoxystannanes can also be prepared by the addition of an organotin hydride to a carbonyl compound (equation 14-5), and by the Sh2 reaction of alkoxyl radicals with organotin compounds carrying electronegative ligands (Section 11.4), for example equation 14-6, but these reactions have not been widely used for preparative purposes. 

We have also initiated MUssbauer spectroscopic studies of photochemical reactions of inorganic and organometallic compounds (iron chelate complexes, iron carbonyl and organotin compounds) isolated in low temperature matrices. Such systems provide a complimentary approach to solid-phase photochemistry since the reaction mechanisms may be simplified by isolating the reactant molecules in inert matrices (light transmission through the reactant is also facilitated by diluting tlie colored reactant with a transparent medium). Furthermore, we have a hope for the possible outcome of such studies — their application to syntheses of novel species which may be unstable at ordinary temperatures, unless trapped in inert matrices. 

Cyanohydrins. The organotin compound catalyzes the Mukaiyama aldol reaction, the derivatization of carbonyl compounds with MejSiCN, and other Lewis acid-catalyzed processes at -78°. It is prepared from diallyltin dibromide by reaction with pentafluorophenylmagnesium bromide followed by bromolysis. 

Dithioacetals, 1,3-dithianes or 13-dithiolanes are prepared by reaction of the corresponding carbonyl compound in the presence of an acid catalyst (cone. HQ, Lewis acids such as Znh, BFs EtaO, TMS-Cl, etc.) with a thiol or dithiol. Silica gel treated with thionyl chloride was found to be an effective as well as selective catalyst for thioacetalization of aldehydes. Thioacetalization can also be achieved using a (polystyryl)diphenylphosphine-4odine complex as a catalyst Conversion of aldehydes or acetals into 1,3-dithianes is achieved with the aid of organotin thioalkoxides and organotin triflates or with 2,2-di-methyl-2-sila-l,3-dithiane. Direct conversion of carboxylic acids to 1,3-dithianes can be carried out by reaction with 1,3,2-dithiabomenane-dimethyl sulfide and tin(II) chloride or 1,3,2-dithiaborolene with trichloromethyllithium followed by basic hydrolysis. 

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