Stannyl halides

Bis(stannyl halides) of suitable geometry can act as bidentate Lewis acids. The compounds XPh2Sn(CI I2) SnPh2X, n= 1, 2, or 3, all form 1 1 adducts 29 with halide ion, preferentially chelating F rather than CL or BL. 

Compound 211 and several related compounds are readily accessible by stereospecific deprotonation of the appropriate optically active carbamic esters with 5-BuLi/TMEDA ° . Much of the knowledge about the stereochemical course of substitution in benzyUithium derivatives was obtained from experiments with these compounds. Only the reaction with proton acids, aliphatic aldehydes, ketones or esters as electrophiles proceed with retention for alkyl, silyl and stannyl halides, acid chlorides. 

Lithium tetrakis[methyltelluro]aluminate, prepared from methanetellurol and lithium aluminum hydride, reacted with silyl, germyl, and stannyl halides at low temperatures to produce, for instance, methyl silyl tellurium derivatives1. 

Tin Derivatives A convenient and direct method for the preparation of metallated species in the azole series starts with lithiation, as in the case of rr-excessive systems. In thiazoles the initial lithiation is in the 2-position. Subseqnent qnenching with a stannyl halide will furnish a stannane snbstrate 100 to be used for Stille couplings with aryl or heteroaryl halides, in the present case with a bromide (Scheme 42). Stannylated oxazoles are similarly prepared and react in the same manner.The same applies to their benzannulated analogs 101. ... 

Thiophene undergoes metalation in the 2-position by reaction with -butylhthium. The resulting 2-lithiothiophene is susceptible to various electrophiUc reactions, for example, with alkyl, silyl, or stannyl halides ... 

The stannyl halides can be generated in situ by reactions of allylic halides with tin metal or with stannous halides. 

Reactions of tetrallylstannanes with aldehydes catalyzed by SnCU also appear to involve a stannyl halide intermediate. It can be demonstrated by NMR spectroscopy that there is a rapid-redistribution of the allyl group. ... 

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