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

Abstract

A metal- and oxidant-free method for preparing 3-selenocyanato-substituted chromones from 2-hydroxyphenyl enaminones by using a newly developed electrophilic selenocyanating reagent is reported­. A series of 3-selenocyanato- or 3-thiocyanato-substituted chromones, as well as 3-selenocyanato- or 3-thiocyanato-substituted quinolinones was obtained in good to excellent yields under grinding reaction conditions. The generality and utility of this approach were demonstrated by a scale-up reaction and transformations of one of the products.

“Green Is the Color”: An Update on Ecofriendly Aspects of Organoselenium Chemistry

“…More recently, Xiao, Ren and co-workers reported a grinding-mediated electrophilic cyclization of 2-substituted enaminones 83 in the presence of N -selenocyanophthalimide 84 as a selenocyanating reagent to afford 3-selenocianato-substituted chromones 85 [ 100 ]. The reactions were conducted in an agate mortar in the absence of solvent, and after grinding for just 20 min at room temperature, the desired products 85 were obtained in moderate to excellent yields, presenting a good substrate tolerance.…”

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

“…When 1‐acetyl‐2‐naphthol enaminone ( 58 l ) and 3,5‐dichloro‐2‐hydroxyphenyl enaminone ( 58 m ) were reacted under these reaction conditions, the resulting selenocyanates ( 60 l and 60 m ) were achieved in good yields (Scheme 31a). The selenocyanation was also accomplished well on various N ‐protected 2‐aminophenyl enaminones ( 61 a – 61 d ) with different substituents with the newly produced selenocyanatophthalimide reagent ( 59 ), producing the corresponding selenocyanated quinolinones ( 62 a – 62 d ) in good to moderate yields (Scheme 31b) [28] . The author suggested that the imine intermediate 58 A be provided through an electrophilic selenocyanation process using selenocyanating agent 59 .…”

“…Huang and coworkers used a newly produced electrophilic selenocyanato‐phthalimide reagent 59 to create an effective method for the synthesis of 3‐selenocyanato‐substituted chromones 60 and quinolinones 62 from various enaminone derivatives ( 58 or 61 ) in good to high yields under grinding conditions [28] . The reaction exhibited remarkable functional group adaptability regardless of the nature (electron accepting or ‐releasing groups) as well as at any position of the substituents on the aromatic part of the 2‐hydroxyphenyl enaminone derivatives ( 58 a – 58 k ).…”

“…Subsequently, dimethylamine is removed from 58 B to obtain the expected selenocyanate product 60 (Scheme 32). [28] …”

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

“…Very recently,X iao, Ren, Huang, and co-workers reported the synthesis of the electrophilic selenocyanate source XIII [35] from N-chlorophthalimide and silver selenocyanate in 87 %y ield (Scheme 28). [36] The selenocyanatophthalimide reagent XIII was then appliedt ot he selenocyanation of enaminone derivatives 85 or 87,w hich after cyclization led to the corresponding 3-selenocyanato-substituted chromones 86 and quinolinones 88.…”