H. Tavakol and S. Zakery, Diastreoselective addition to SAMP hydrazones  12^th Iranian seminar of Organic Chemistry, Ahwaz jundi shapour university of medical science, Ahwaz, Iran, 7-9 March 2006

Abstract

The addition of nucleophiles to a carbon-nitrogen double bond (such as imines, hydrazones, and oximes) has become an extremely useful process for the synthesis of a variety of amines, a-amino acids, a-aminophosphonates and other compounds of interest.¹ Typically organosilane reagents can be utilized to achieve this carbon-carbon bond forming reaction.² Three factors which often diminish the versatility of these reactions are poor electrophilicity carbon-nitrogen double versus carbonyl group, enolization of substrates with a-hydrogen and the formation of reductive coupling products.³ In many cases, these problems can be overcome by using more activated imine derivatives (iminium salts, acylimines, sulfonimines, nitrones, hydrazones and oximes) or less basic reagents. Also, because of importance of chiral compounds in nature and human body, the synthesis of this compound is very important in organic synthesis and one of the most methods for preparation of these compounds is diastreoselective synthesis. In these reactions, we use an auxiliary compound to prepare the favorite isomer more than other isomers. This named asymmetric induction.

Recently, we have demonstrated the synthetic utility of lithium perchlorate/ diethyl ether (LPDE) solution in the preparation of several nitrogen-containing compounds in addition of nucleophiles to C=N double bond^4,5. Then we have focused our attention on the use of SAMP-Hydrazoners as an auxiliary in diastreoselective addition of Trimethylsilylcyanide to C=N bond of prepared hydrazones (from SAMP and various aldehydes) for preparation of chiral α-Cyanohydrazines that we can convert them simply to corresponding chiral a-amino acids. In Scheme 1, we wish to report a mild, simple and efficient conversion of aldehydes to chiral α-Cyanohydrazines via SAMP-hydrazones in LPDE solution. In this reaction SAMP-hydrazones, formed in situ by the mixture of aliphatic aldehyde and SAMP, is submitted to a nucleophilic attack of trimethylsilyl cyanide (Scheme 1), in when we used aliphatic aldehydes, the desired products were obtained in high yields with good diastreomeric ratio.