Organotin Enolate

In a separate report, preparation of the lithium enolate of 31 in the presence of indium trichloride and benzaldehyde provided a 77% yield of 32 with complete trans selectivity however, sequential addition of indium trichloride and benzaldehyde provided Barbier-type products. Organotin enolates have also been used in a Darzens-type... 

Organotin Enolates in Organic Synthesis. A Review," Shibata. L Baba, A. Org, Prep. Proceed. Int, 1994, 26, 123... 

The keto/enol ratio in organotin enolates is dependent on the enol structure and on the environmental conditions, a good ligand for the tin shifting the equilibrium toward the enolate, and increasing its reactivity (Equation (142)).392... 

Tin enolates are one of the most versatile reagents for carbon-carbon bond formation. They are used either in ionic or radical reaction manner. Organotin enolates exist as equilibrium mixtures of keto and/or enol forms, and their ratio largely depends on their substituents and conditions (Equation (66)).220 In general, an enol form has high nucleo-philicity in ionic system and thus only the enol form is often shown in a reaction scheme. 

Organotin enolates (vinyloxystannanes) (14-18), containing an Sn-0 bond, are in metal-lotropic equilibrium with the corresponding Sn-C bonded a-stannylcarbonyl compounds (14-19), providing a further example of the equivalent behaviour of hydrogen (prototropy) and metals (metallotropy) (Section 3.1.1.7). 

Without any catalyst, organotin enolates react with allylic halides to afford the monoallylation products (eq (122)) [117]. Alkenyl halides, aryl halides, and allylic acetates can be used for the alkylation of tin enolates when the reactions are catalyzed... 

Five reviews have appeared entitled A mechanistic investigation of gelation. The sol-gel polymerization of precursors to bridged polysilsequioxanes , which contains Si NMR data, Derivatives of hydroxamic acids , which contains Si NMR data, A primer on the aqueous chemistry of silicon , which contains Si NMR data, Organotin(IV) complexes of amino acids and peptides , which contains Sn NMR data, and Novel reaction system using highly coordinated organotin enolates . ... 

The Mukaiyama aldol reaction is a favorable method for the synthesis of P-hydroxy carbonyl compounds in terms of environmental friendliness because the process uses less toxic silyl enolates compared to organotin enolates [52]. Yamagishi and CO workers have examined a BI NAPAg( I)-catalyzed asymmetric Mukaiyama aldol reaction with trimethylsilyl enolates and have found that the reaction is accelerated by BINAP-AgPFe in DMF containing a small amount of water to give the aldol adduct with high enantioselectivity (Scheme 18.14) [53]. 

A 3-fold excess of ethyl iodide added to the startg. organotin enolate, and heated 60 hrs. at 120° in an inert atmosphere with exclusion of moisture 2-ethyl-2-methylcyclohexanone. Y 76%. F. e. s. Y. Odic and M. Pereyre, J. Organometal. Chem. 55, 273 (1973). 

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