203798-72-5

Upstream product

• 65-85-0 benzoic acid 
• 203798-70-3 (S)-3-(3,4-Bis-benzyloxy-phenyl)-2-hydroxy-propionic acid methyl ester 
• 100-44-7 benzyl chloride 
• 136749-45-6 (+)-(S)-methyl 3-(3,4-dihydroxyphenyl)-2-hydroxypropanoate 

Downstream Products

• 203798-85-0 (E)-3-(3,4-Bis-benzyloxy-phenyl)-acrylic acid (R)-2-(3,4-bis-benzyloxy-phenyl)-1-methoxycarbonyl-ethyl ester 
• 99353-00-1 rosmarinic acid methyl ester 
• 203798-74-7 (R)-methyl 3-(3,4-bis(benzyloxy)phenyl)-2-hydroxypropanoate 

Relevant academic research and scientific papers

Synthesis of enantiomeric (+)- and (-)-rosmarinic acid methylesters

Starting from L-tyrosine (L-1), the phenyl lactic acid ester (-)-4 was prepared by reported procedures. (-)-4 could then be converted to the benzyl ether (-)-5. From (-)-5, the corresponding optical antipode (+)-5 is available via (+)-6 by Mitsunobu reaction. The enantiomeric excess of 5 was determined by NMR spectroscopy from camphanic acid esters (+)- and (-)-8, respectively. The phenyl lactic acid esters (+)- and (-)-5 were acylated by caffeoyl chloride (9) to yield the O-protected enantiomeric rosmarinic acid esters (+)- and (-)-10. Deprotection of 10 by BCl3 afforded the title compounds (+)- and (-)-11 in fair yields.