82808-07-9

Upstream product

• 3886-69-9 (R)-1-phenyl-ethyl-amine 
• 66892-34-0 6-fluoro-4-chromanone 

Downstream Products

• 82799-09-5 (R)-2,3-dihydro-6-fluoro-3'-<(R)-1-phenylethyl>spiro<4H-1-benzopyran-4,4'-imidazolidine>-2',5'-dione 
• 82799-11-9 (R)-6-fluoro-2,3-dihydro-5'-imino-3'-<(R)-1-phenylethyl>spiro<4H-1-benzopyran-4,4'-imidazolidin>-2'-one hemisulfate 
• 82799-08-4 (R)-4-cyano-2,3-dihydro-6-fluoro-4-<(R)-(1-phenylethyl)amino>-4H-1-benzopyran 

Relevant academic research and scientific papers

Synthesis of Optically Active Spirohydantoins by Asymmetric Induction. Hydantoin Formation from Amino Nitriles and Chlorosulfonyl Isocyanate

Conversion of 6-chloro- or 6-fluoro-2,3-dihydro-4H-1-benzopyran-4-one with optically active (S)-α-methylbenzylamine in the presence of TiCl4 to the ketimine followed by treatment in EtOH with HCN gas gives excellent yields of crystalline, enantiomerically pure (4S)-4-cyano-2,3-dihydro-6-chloro(or 6-fluoro)-4--4H-1-benzopyran.These sterically hindered amino nitriles react smoothly with chlorosulfonyl isocyanate to give, after hydrolysis, the hydantoins (4S)-2,3-dihydro-6-chloro(or 6-fluoro)-3'-spiro-2',5'-dione.The α-methylbenzyl groups can be removed by aqueous HBr/acetic acid to give the unprotected spirohydantoins.