Reverse Kocheshkov reaction – Redistribution reactions between RSn(OCH2CH2NMe2)2Cl (R = Alk, Ar) and PhSnCl3: Experimental and DFT study

A series of organotin compounds bearing two intramolecular N → Sn coordination bonds RSn(OCH2CH2NMe2)2Cl (R = Me (4), n-Bu (5), Mes (6)) were synthesized in good yields. These compounds as well as 2 (R = Ph) react with PhSnCl3 to give redistribution products RPhSnCl2 and (Me2NCH2CH2O)2SnCl2 (3). The direction of redistribution reactions is reverse to Kocheshkov reaction. DFT calculations have shown that the driving force of the reactions is formation of intramolecular N → Sn coordination bonds in (RO)2SnCl2 (3), the Lewis acid stronger than RSn(OR)2Cl (2, 4–6). The mechanism of the redistribution reaction between 2 and PhSnCl3 consists of two steps: (1) initial exchange of OCH2CH2NMe2 and Cl to give PhSn(OCH2CH2NMe2)Cl2 (7) followed by (2). Ph and OCH2CH2NMe2 exchange.

The presence of OCH2CH2NMe2 groups significantly increase the mobility of R substituents in RSn(OCH2CH2NMe2)2Cl (R = Alk, Ar). These compounds react with PhSnCl3 to give a reverse Kocheshkov reaction products (Me2NCH2CH2O)2SnCl2 and RPhSnCl2. Tin species bearing coordinating groups collect electronegative substituents and release electropositive ones.Figure optionsDownload as PowerPoint slide