Cyclization of unsaturated imines

The electrophilic cyclization of unsaturated imines derived from glyoxalate, catalyzed by ytterbium triflate, gives reduced furo[3,4- ]pyridines in variable yields, but with good stereoselectivity (Equation 16) <2002TL2339>. For the 5 6 ring system, the /ra t-isomer, 73, is the primary product formed. 

Photochemical cyclization of unsaturated imines of type 145a can give excellent yields of quinolines (Scheme 12) (93TL5321). 

Photochemical cyclization of unsaturated imines 124 gives quinolines 125 in excellent yields (Scheme 73) C1993TL5321, 1996JOC7195, CHEC-III(7.05.2.1.3)234>. 

Electrophilic cyclization of unsaturated imines was accomplished with bromine under mild conditions to give piperidines or pyrrolidines, depending on substitution pattern (94TL(35)1925>. 

---

See also in sourсe #XX -- [ , ]

---