Chloro sulfonic acid ethyl ester

CHLOROETHYLMETHANESULFONATE CHLOROETHYL METHANESULPHONATE CHLORO-METHANE SULFONATE d ETHYLE (TRENCH) METHANESULFONIC ACID CHLOROETHYL ESTER NSC-18016... 

Heterocyclic fluorophores based on the benzoxadiazole nucleous, namely 4-nitrobenz-2-oxa-l,3-diazole (NBD) 14 derivatives/analogs, have been widely used as derivatization reagents for analysis purposes. Examples include the amino- or thiol reactive 4-fluoro-7-nitrobenz-2-oxa-l,3-diazole (NBD-F) 15 and 4-chloro-7-nitrobenz-2-oxa-1,3-diazole (NBD-C1) 16 [45-50] and the thiol-reactive /V-((2-(iodoacetoxy)ethyl)-/V-methyl)amino-7-nitrobenz-2-oxa-1,3-dia-zole (IANBD ester) 17 [51] and 7-chlorobenz-2-oxa-l,3-diazole-4-sulfonate (SBD-C1) 18 [52], NBD-F and NBD-C1 derivatives can be excited at about 470 nm by using the relatively inexpensive and reliable argon ion lasers or newer diode pumped solid state (DPSS) lasers. NBD-F has been used as a labeling tag in various capillary electrophoresis (CE) experiments for amino acids [53-57] including the monitorization of in vivo dynamics of amino acids neurotransmitters [58]. 

One Sanofi synthesis of enantiomerically pure (-i-)-clopidogrel (2) utilized optically pure (R)-(2-chloro-phenyl)-hydroxy-acetic acid (20), a mandelic acid derivative, available from a chiral pool. After formation of methyl ester 21, tosylation of (/ )-21 using toluene sulfonyl chloride led to a-tolenesulfonate ester 22. Subsequently, the Sn2 displacement of 22 with thieno[3,2-c]pyridine (8) then constructed (-i-)-clopidogrel (2). Another Sanofi synthesis of enantiomerically pure (-i-)-clopidogrel (2) took advantage of resolution of racemic a-amino acid 23 to access (S)-23. The methyl ester 24 was prepared by treatment of (S)-23 with thionyl chloride and methanol. Subsequent Sn2 displacement of (2-thienyl)-ethyl para-toluene-sulfonate (25) assembled amine 26. 

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