allowed to warm to room temperature and allowed to react for additional 4 h the reaction mixture was stripped of solvent in vacuo at 85 u00b0 c over 4 h to obtain a tacky solid 28 g the solid was dissolved in 140 ml of anhydrous thf and 20 g of cdi and a catalytic quantity of dmap were added and allowed to react at a reflux for 6 h until a large amount of white solid precipitated the white solid was cooled and filtered to yield 18 g of dried title compound 1 h nmr dmso d 6 u03b4 11 10 s 1h 8 26 s 2h 5 03 dd 1h j 3 hz j 3 hz 2 87 2 82 m 1h 2 66 2 55 m 2h 2 07 2 04 m 1h ms m z 263 m u2212 1 1 54 g thieno 3 4 c furan 1 3 dione was dissolved in 20 ml of anhydrous thf and 12 8 g of 3 aminopiperidine 2 6 dione was added the reaction mixture was allowed to react at room temperature for 4 h then 2 g of cdi and a catalytic quantity of dmap were added and the reaction mixture was allowed to reflux for 6 h until a large amount of white.