Benzopyran compounds possess diverse pharmacological properties such as β-blockade, anticonvulsant and antimicrobial.[1,2] Our interest has been focused on the synthesis of 1-[6-Fluoro-2S]-3H,4H-dihydro-2H-2-chromenyl]-(1R)-1,2-ethanediol (6) and 1-[6-fluoro-(2R)-3H,4H-dihydro-2H-2-chromenyl]-(1R)-1,2-ethanediol (7) which are particularly convenient precursor to (S,R,R,R)-NE (8). 8 containing four asymmetrical carbon atoms was reported to be the most active isomer.[3] Chandrasekhar[4] has reported on the synthesis of 8. The key step to synthesize this compound is to obtain the chiral chromanone 6 and 7. 6 was accomplished in 8 steps by the Clasien rearrangement and a one-pot Sharpless asymmetric epoxidation, but the compound 7 was accomplished in 10 steps. Johannes[5] used Zr-catalytic kinetic resolution of allylic ethers and Mo-catalyzed chromene formation to synthesize 8 in 14 steps. However both of the methods request many synthetic steps and expensive reagents.……
The design of readily accessible nicotinamide adenine dinucleotide hydride (NADH) model compounds combining hi...
ZHAO,Jia WANG, Nai-Xing YU,An-Guang ZHANG, Jun-Ping YANG, Yun-Xu WANG, Wu-Wei SHENG, Rui-Long (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100101)
Lithium aluminium amide [LiAI（NHR）4] 5 obtained by treating the primary amine 4 with LiAlH4 could promote the ring opening of epoxide 2 and led to high regioselective product of racemic bis[2-（6-fluoro-2-chromanyl）-2-hydroxyethyl]amine methanesulfonic acid salt 7.
