Intramolecular, reductive cyclization of beta-ketoisothiocyanates promoted by using samarium diiodide.
A novel samarium diiodide (SmI2) promoted intramolecular cyclization of beta-ketoisothiocyanate, derived from alpha,beta-unsaturated esters and ammonium thiocyanate led to alpha-hydroxythiolactams and/or thiolactams in high yields. Treatment of beta-ketoisothiocyanate with two equivalents of SmI2 gave a mixture of alpha-hydroxythiolactam and thiolactam. Four equivalents of SmI2 afforded only thiolactam in high yields. The intramolecular cyclization took place with high to complete stereoselectivity. A mechanism to explain this transformation is proposed.
Cho
Min Seok
MS
Department of Chemistry, Center for Molecular Design and Synthesis, Korea Advanced Institute of Science and Technology, Daejon, 305-701, Korea.
Lee
In Sang
IS
Kang
Sung Ho
SH
Kim
Yong Hae
YH
D003500:Cyclization; D007454:Iodides / Q000737:chemistry*; D017879:Isothiocyanates / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D007769:Lactams / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D012493:Samarium / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
D007454:Iodides; D017879:Isothiocyanates; D007659:Ketones; D007769:Lactams; D012493:Samarium; C409809:samarium diiodide