Novel ap­proach for for­ma­tion of car­bon ni­tro­gen bonds

Chemical Industry Digest - - Science Pages -

Re­searchers at Rice Uni­ver­sity, Hous­ton, have de­vised a non cat­alytic ap­proach to the for­ma­tion of car­bon-ni­tro­gen bonds. Their method, which re­lies on an umpol­ung (po­lar­ity-re­ver­sal) reagent, prom­ises an op­er­a­tionally sim­ple, scal­able and en­vi­ron­men­tal friendly al­ter­na­tive to cur­rent tran­si­tion­metal-cat­alyzed cross-cou­pling routes for pro­duc­ing amines, they believe.

The method can di­rectly pro­duce sym­met­ri­cal and un­sym­met­ri­cal di­aryl-, ary­lalkyl- and di­alky­lamines. The de­vel­op­ment of a prac­ti­cal sin­gle and dou­ble umpol­ung of ni­tro­gen pro­vides un­prece­dented flex­i­bil­ity for com­ing up with ef­fi­cient syn­the­sis routes, the re- searchers believe.

“Over­all, this new N-umpol­ung ap­proach opens up chem­i­cal routes that were pre­vi­ously only avail­able by the use of ex­pen­sive tran­si­tion me­tals and lig­ands. One huge ad­van­tage here is that no lengthy op­ti­miza­tion is re­quired when a par­tic­u­lar C–N bond is to be made. Even aryl-ni­tro­gen bonds can be pre­pared at or be­low am­bi­ent tem­per­a­tures. The N-umpol­ung reagent is in­ex­pen­sive, the aryl- as well as alkyl Grig­nards are com­mer­cially avail­able or can be read­ily pre­pared,” noted Lás­zló Kürti, an as­so­ci­ate pro­fes­sor of chem­istry at Rice. The find­ings are pub­lished in the Jour­nal of the Amer­i­can Chem­i­cal So­ci­ety (JACS).

“We believe that the de­gree of N-elec­trophilic­ity can be fur­ther mod­u­lated by chang­ing the struc­ture of the N-umpol­ung reagent. There­fore, we are ac­tively mak­ing new and more pow­er­ful N-umpol­ung reagents and eval­u­at­ing these in a va­ri­ety of car­bon-ni­tro­gen bond-form­ing trans­for­ma­tions. In sum­mary, our N-elec­trophilic imines in­deed will likely be very use­ful sub­strates and valu­able N-sources in many mech­a­nis­ti­cally dif­fer­ent trans­for­ma­tions,” says Kurti.

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