A-Aminostannane

Imidoylstannanes, R13SnCR2=NR3, can be prepared from the reaction of stannyllithium compounds with the corresponding imidoyl chlorides (C1CR2=NR3 R2 and R3 = aryl),163 or, more generally, from the reaction of an acylstannane with an amine.164 The imidoylstannane can then be reduced to an a-aminostannane (Equation (49)).165... 

Furtheimore, it was first shown nearly 20 years ago that a-lithioamines could be produced by the transmetalation of a-aminostannanes. Thus, the thermodynamic stability of a-amino anions is reasonably good, even if the kinetic acidity of the conjugate acids is low. Although some authors have suggested that a-amino carbanions constitute a reversal of normal reactivity, we suggest that this notion is inappropriate and should be discontinued. 

Ye J, Bhatt RK, Falck JR (1994) Stereospecific palladium/copper cocatalyzed crosscoupling of a-alkoxy- and a-aminostannanes with acyl chlorides. J Am Chem Soc 116 1-5... 

Guram, A. S., Buchwald, S. L. Palladium-Catalyzed Aromatic Aminations with in situ Generated Aminostannanes. J. Am. Chem. See. 1994, 116,7901-7902. 

The acidity of the cyclopentadienes makes the cyclopentadienyltin compounds readily accessible97 either through the reaction of other cyclopentadienylmetal derivatives with tin(IV) halides (equation 9-44),99 or by acidolysis of an aminostannane with a cyclopentadiene (equation 9-45).100 101 Ferrocenylstannanes can also be obtained from ferrocenylmercury compounds and organotin sulfides (equation 9-54).102... 

The principal compounds with an SnN covalent bond are the aminostannanes containing the structure Sn-NR2 and the amidostannanes and sulfonamidostannanes containing the structures SnNRC(0)R or SnNRS(0)2R, respectively. A few compounds containing a tin-nitrogen double bond, Sn=NR, have also been identified. 

The aminostannanes are usually prepared by transmetallation between an organotin compound such as a halide and an aminometallic compound by transamination of a stannylamine by addition of a tin reagent to a multiple bond to nitrogen, or by an ene reaction (equations 16-1-16-4). The Sn-N bond which is formed is very reactive towards moisture and carbon dioxide, and the reactions must be carried out in an inert atmosphere. 

Hydrolysis occurs very readily to give the organotin hydroxides or oxides, and the stannylamines must be prepared, stored and handled under dry, CC -free, conditions. The organotin derivatives of pyrrole are less sensitive, and their hydrolysis is reversible.3 Alcoholysis of the aminostannanes provides a clean route under mild conditions to the... 

An aminostannane intermediate is involved in the homolytic reduction of an azide to the corresponding amine,33 and in the conversion of a-azido-P-ketoesters into amides and lactams (equations 16-41 and 16-42).34... 

Amidostannanes containing the groups Sn-NC(=0)R or Sn-NS(0)2R are easier to prepare and to handle than are the aminostannanes. The acidity of the proton on nitrogen in the parent amide is now sufficient for reaction to occur with organotin hydroxides, oxides, and alkoxides (and aminotin compounds), and, once formed, the amidostannanes are less sensitive to moisture. A variety of amidostannanes is also available from the addition of Sn-0 and Sn-N bonded compounds to nitrogen heterocumulenes. 

Acidolysis of an aminostannane with a phosphine or arsine provides a clean route to the stannyl-phosphines and -arsines (Section 16.1.3.1), and, under more forcing conditions, the phosphines can be prepared from bis(tributyltin) oxide.73... 

Kosugi and co-workers reported that palladium complexes with P(o-tolyl)3 as ligand would catalyze the formation of arylamines from aryl halides and aminostannanes (Eq. A subsequent fuU paper demonstrated the scope and limitations of this... 

The first demonstration of palladium catalysis in an aryl amination reaction was reported in 1983 by Kosugi and co-workers. In this reaction, an aminostannane is coupled to an aryl halide in a transformation analogous to a Stille cross-coupling. 

In 1994, Buchwald and co-workers improved this original procedure by developing a method for in situ generation of the aminostannane. Simultaneously, Hartwig and co-workers obtained an X-ray crystal structure of a catalytically active Sn-Pd complex, furthering our understanding of the... 

Labadie et synthesized a munber of organotin polymers and reported their resist properties. These products included homopolymers of stannylalkyl methacrylates that crosslinked upon e-beam exposme. It is interesting that copolymers containing methyl methacrylate units degraded on e-beam exposure. Polymers containing tin in the backbone were prepared by condensation of aminostannanes with a,03-diynes followed by crosslinking upon e-beam exposure. A 15 wt % tin content was required to obtain etch rate selectivities of > 15 1 relative to the corresponding non-tin polymer. 

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