Lewis Acid-Catalyzed Asymmetric Selenocyanation of β-Ketoesters with N-Selenocyanatosaccharin

Abstract

The first electrophilic asymmetric selenocyanation has been achieved in the presence of Ni(OTf) 2 and (R,R)-DBFOX/Ph using N-selenocyanatosaccharin as the new selenocyanation reagent. Thus, a series of α-selenocyanato-βketo esters were synthesized with high yields (up to 99%) and good ee values (up to 92% ee). The readily preparation of the reagent and high enantioselectivity make this methodology much practical for the synthesis of chiral selenocyanates.

Organic Selenocyanates: Rapid Advancements and Applicationsin the Field of Organic Chemistry

“…Using tert‐butyl hypochlorite to treat saccharin, and AgSeCN to react the resulting N‐chlorosaccharin, this reagent was accomplished in two steps on a gram scale (68% overall yield). For the first time, this reagent was employed for asymmetric selenocyanation of β‐keto carbonyl compounds 44 with Lewis acid catalysis in order to achieve chiral α‐selenocyanato‐β‐keto esters 46 [23] . The reaction proceeds at −78 °C temperature in dichloromethane (CH 2 Cl 2 ) and gives selenocyanated products ( 46 a – 46 m ) with good to excellent yields (59‐99%) with moderate to good enantioselectivities (up to 92%) and a long reaction time for both electron‐accepting or ‐releasing substituents on the phenyl ring of the tetralone derivatives ( 46 a – 46 c ).…”

Design and Use of Electrophilic Thiocyanating and Selenocyanating Reagents: An Interesting Trend for the Construction of SCN‐ and SeCN‐Containing Compounds

“…Very recently, Chen's group developed a methodology for the asymmetric selenocyanation of β‐ketoesters by means of Lewis acid catalysis (Scheme 27). [34] To reach that goal, a new electrophilic reagent XII derived from saccharin was synthesized in two steps in an overall 68 % yield. In the presence of the selenocyanatosaccharin XII , a nickel‐catalyzed selenocyanation of various β‐ketoesters was achieved in high yields (up to 99 % yield) and a good control of the enantioselectivity (up to 92 % ee ).…”

Straightforward Synthesis of 3-Selenocyanato-Substituted Chromones through Electrophilic Selenocyanation of Enaminones under Grinding Conditions

“…15 More recently, Chen and co-workers reported the asymmetric selenocyanation of -keto esters with newly developed N-selenocyanatosaccharin. 16 Since then, the development of novel electrophilic selenocyanating reagents to access selenocyanates have been rare. We envisioned that a new selenocyanating reagent, namely N-selenocyanatophthalimide (PhthSeCN) could be prepared by a procedure similar to that used for BI-SeCN and used to yield selenocyanates by the selenocyanation of 2-hydroxyphenyl enaminones under grinding conditions.…”