Haloacetyl

A series of meta- and para-bis (2-thiazolyI) benzenes and of meta- and para-bis(4-thiazolyl)benzenes of general formula 35 and 36 was prepared in higher yields (60-90%) from the appropriate bis-(haloacetyl)benzenes with a suitable thioamide (Scheme 18a and Table JI-8) (573, 574),... 

Bis (meta or para haloacetyl) benzenes (C1CH2C0)2C6H4 condensed with thiourea yield the corresponding meta or para bis(4-thiazolyl-2-amino)phenylene (573, 574), analogous to 36 with R=NH2-By refluxing in alcohol solution m- or p-2-thiazolylphenacyl bromide (37) with thiourea, compound 111, in which R = H, Ph, P-CIC6H4, and p-OjNC H, was obtained (569). 

Haloacetyl groups have also a synthetic potential. Thus, pesticidal (alkylthio)-vinyl esters of phosphorus acid derivatives have been prepared by the introduction and subsequent displacement of two chlorine atoms in the acetyl moiety attached to the furazan ring (Scheme 69) [73GEP(0)2144393]. 

A three-stage procedure is more versatile and gives higher yields. In this method (Method B), the 2-aminobenzophenone is treated with an a-haloacetyl halide and the resulting haloacetamide 5 converted into an aminoacetamide 6 by reaction with ammonia. Cyclization to the benzo-diazepinone 7 occurrs readily. In some cases the intermediates 5 and 6 are not isolated selected examples are given.193 94... 

Table 7.6 Exhaustion and fixation of haloacetyl-substituted disazo dyes on silk [119]...

Reaction of ot-haloacetyl bromides with amides in the presence of strong acids... 

Haloacetyl Method The haloacetyl method uses supports that contain lodoacetyl or bromoacetyl groups for the immobilization of ligands through sulfhydryl residues. These supports are usually prepared via the reaction of an amine-containing material with iodoacetic or bromoacetic acid in the presence of ethyldimethylaminopropyl carbodii-mide (EDC) at pH 4 to 5. EDC reacts with the carboxylic acid in iodo- or bromoacetic acid... 

Numerous researchers have employed thiols as weak bases in the thioalkylation reaction to ligate unprotected peptides with a haloacetyl group to form thioethers at pH 7 8.5[90 91 131-133 or thioesters at acidic to basic conditions. 108"110 Of these two reactions, thioether formation is often the choice because thioesters suffer from instability in aqueous basic conditions. Haloacetyl derivatives, either as carboxylic acids or active esters, can be attached to either the N-terminal or side-chain amines during the stepwise solid-phase synthesis of either the peptide or the core and are stable to either HF or TFA cleavage conditions. Capping an amino group with a chloroacetyl group is compatible with Fmoc chemistry when used at a terminal step. 

A further indication supporting the haloacetyl structure 63 of the C2H2OX+ ions generated by 56, 57 and 58 is the observation that under El their labeled analogues XCH2COOCD3 exclusively lose OCD3 without H/D exchange. Finally, comparison of the... 

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