Tributyltin cyanide

Strecker reactions provide one of the most efficient methods for the synthesis of a-amino nitriles, which are useful intermediates in the synthesis of amino acids and nitrogen-containing heterocycles. Although classical Strecker reactions have some limitations, use of trimethylsilyl cyanide (TMSCN) as a cyano anion source provides promising and safer routes to these compounds.133-351 Consequently, we focused our attention on tributyltin cyanide (Bu3SnCN), because Bu3SnCN is stable in water and is also a potential cyano anion source. Indeed, the Strecker-type reactions of aldehydes, amines, and Bu3SnCN proceeded smoothly in water (Eq. 9).1361 It should be noted that no surfactants are required in this reaction. Furthermore, Complete recovery of the toxic tin compounds is also possible in the form of bis(tributyltin) oxide after the reaction is over. Since conversion of bis(tributyltin) oxide to tributyltin cyanide is known in the literature, this procedure provides a solution to the problem associated with toxicity of tin compounds. 

S. Kobayashi, T. Busujima, S. Nagayama, Scandium Triflate-Catalyzed Strecker-Type Readions of Aldehydes, Amines, and Tributyltin Cyanide in Both Organic and Aqueous Solutions. Achievement of Com-plde Recovery of the Tin Compounds toward Environmentally Friendly Chemical Processes Chem. Commun 1998, 981-982. 

A clean, Strecker-type synthesis of a-aminonitriles has been developed amine, aldehyde, tributyltin cyanide, and scandium(III) triflate (as catalyst) are mixed together at room temperature. Yields for a range of aliphatic and aromatic aldehydes are typically ca 90%, the solvent can be organic or aqueous, the 10% catalyst loading is recoverable and reusable, and the tin reagent is similarly recyclable. 

The 8-0-trifluoromethanesulfonate substituent on the aromatic B-ring of the duocarmycin derivative DU-86 78 can be replaced in acceptable yields using either palladium(0)-catalyzed reduction or cyanation with tributyltin cyanide (Equation 16) <1996BMC1379>. 

R. Herranz, J. Castro-Picliel, and T. Garcia-Ldpez, Tributyltin cyanide, a novel reagent for the stereoselective preparation of 3-amino-2-hydroxy acids via cyanohydrin intermediates, Synthesis p. 703 (1989). 

Kobayashi and co-workers employed the chiral zirconium binuclear catalyst 22 in the asymmetric Strecker-type synthesis of a-aminonitriles 23 from aldimines 21 with tributyltin cyanide (Scheme 8) [13]. Aldimines 21 were in turn derived from aliphatic, aromatic, and... 

Dechlorination of 4-chloro-6-methylthieno[2,3-d]pyrimidine 164 with zinc in ethanol and acetic acid at 80°C gave compound 165. The latter was subjected to the Reissert reaction using two equivalents each of tributyltin cyanide and acyl chloride in dichloromethane at room temperature. With benzoyl chloride the mono-Reissert adduct 166 was obtained, whereas with acetyl chloride the di-Reissert product 167 (86JHC545). 

With tributyltin cyanide in the presence of benzoyl chloride or acetyl chloride, 6-methylthieno[2,3-d]pyrimidine gave the mono- or di-Reissert aducts 81 and 82, respectively (86JHC545). 

The enantioselective total synthesis of (-)-hemiasterlin, a marine tripeptide with cytotoxic and antimitotic activity, was achieved by E. Vedejs and co-workers. The asymmetric Strecker reaction was used to construct the key tetramethyltryptophan subunit. The aldehyde substrate was first converted to the corresponding chiral imine with (R)-2-phenylglycinol under scandium triflate catalysis. The addition of tributyltin cyanide resulted in the formation of a-amino nitriles as an 8 1 mixture of diastereomers. Subsequently the cyano group was converted to a primary amide, and the chiral auxiliary was removed under catalytic hydrogenation conditions. 

Palladium-catalyzed coaddition of vinyl or aryl halides and cyanides is achieved stereose-lectively (cis-exo) when potassium or sodium cyanide in the presence of palladium(II) acetate and triphenylphosphane in tetrahydrofuran or dimethylformamide is used3173. Palladium-catalyzed addition with copper cyanide, which gives excellent yields in a stoichiometric version15, leads to only small yields of the adduct31, while addition of tributyltin cyanide fails7. 

A recent report9 described the use of scandium triflate in conjunction with tributyltin cyanide, a more water stable cyanide source compared to TMSCN. These reaction conditions could be carried out in both organic and aqueous solutions. It was observed that rare earth triflates are stable Lewis acids in water. Thus, a variety of aldehydes 1 and amine 12 were converted to a-aminonitriles 13 in excellent yield. The spent reagent could be completely recovered and, along with the scandium reagent, recycled for subsequent use. 

The feasibility of a radical attack on the carbon atom of isonitriles was then claimed by Saegusa [4], who studied the reaction of tributyltin hydride with alkyl isonitriles. Formation of alkane and tributyltin cyanide, together with the need for a... 

Tributyltin hydride has been applied to the selective reduction of acid chlorides and 1,3-dithiolanes/ and to the conversion of carboxylic acids and isocyanides " to alkanes. Acyl cyanides are obtained from the treatment of acid chlorides with tributyltin cyanide/ and cyclic ketones are converted into nitro-olefins via the corresponding trimethylvinyltin compound. ... 

The Strecker-type reaction of benzaldehyde, aniline, and tributyltin cyanide was performed on polymer-immobilized scandium triflate [70]. The reaction proceeded cleanly in water (Equation (8.52)) to afford the corresponding a-amino nitrile derivative in high yield. 

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