Protective butoxycarbonyl

The protecting group Y of the amine is generally an alkoxycarbonyl derivative since their nucleophilicity is low. Benzyloxy- or tert-butoxycarbonyl derivatives usually do not undergo azlactone formation. 

A related N terminal protecting group is tert butoxycarbonyl abbreviated Boc... 

Hydrogen bromide may be used to remove either the benzyloxycarbonyl or tert butoxycarbonyl protecting group The benzyloxycarbonyl protect mg group may also be removed by catalytic hydrogenolysis... 

In order to exploit the reactions of the C-lithio derivatives of iV-unsubstituted pyrroles and indoles, protecting groups such as t-butoxycarbonyl, benzenesulfonyl and dimethyl-amino have been used 81JOC157). This is illustrated by the scheme for preparing C-acylated pyrroles (211) (8UOC3760). 

A related N-tenninal-protecting group is ferr-butoxycarbonyl, abbreviated Boc ... 

In 2000, an efficient three-step procedure for the synthesis of 5-substituted 3-isoxazolols (without formation of undesired 5-isoxazolone byproduct) was published. The method uses an activated carboxylic acid derivative to acylate Meldrum s acid, which is treated with A,0-bis(ten-butoxycarbonyl)hydroxylamine to provide the N,0-di-Boc-protected P-keto hydroxamic acids 14. Cyclization to the corresponding 5-substituted 3-isoxazolols 15 occurs upon treatment with hydrochloric acid in 76-99% yield. 

Ester group of l-(ethoxycarbonylmethyl)-7-aryl-5-oxo-1,2,3,5-tetrahydro-pyrido[l,2,3-i/e]quinoxaline-6-carboxamides was hydrolyzed and the 1-carboxymethyl moiety was converted to an aminocarbonylmethyl group with 1-methylpiperazine (01MIP12). Bromo atom of l-(2-bromoacetyl) derivatives was substituted by different amines. An amino group in the side chain attached to the position 1 of 7-aryl-5-oxo-l,2,3,5-tetrahydropyr-ido[l,2,3-i/e]quinoxaline-6-carboxamides was acylated, and terc-butoxycarbonyl protecting group of amino group was eliminated. 

In SPPS, there are two main protecting groups commonly used for Ai -protection [3] ferf-butoxycarbonyl (Boc) [7] and 9-fluorenylmethoxycarbonyl (Fmoc) [8] (Fig. 2). 

The protecting reaction of the enamino pyrrolidinone with t-butoxycarbonyl anhydride was carried out by mixing 4-(N-/-butoxycarbonyl)-4-aminomethylene-pyirolidin-3-one (Boc-AMP) with 1.2 molar equivalents of t-butoxycarbonyl anhydride (/-BoczO) to make l-(N-f-butoxycarbonyl)-4-(N-t-butoxycarbonyl)-ammomethylene-pyrrolidin-3-one (B0C2-AMP). Several types of reactors, including batch reactors, a continuous stirred tank reactor (CSTR),... 

The t-butoxycarbonyl (rBoc) group is another valuable amino-protecting group. The removal in this case is done with an acid such as trifluoroacetic acid or /Moluenesulfonic acid.218 r-Butoxycarbonyl groups are introduced by reaction of amines with f-butoxypyrocarbonate or a mixed carbonate-imidate ester known as BOC-ON. 219... 

The synthesis of these inhibitors is not always straightforward because some hydro-xybenzyl derivatives that have very good leaving groups (like their aminobenzyl analogues) are unstable. Hence, more stable precursors are often used, such as phenyl ethers30-32 or silyl ethers.33-35 Other functional groups present in the molecule must be sometimes protected (/V-terf-butoxycarbonylation of amides for example).36,37... 

Examples are given in Table 4—1 for the synthesis of amides of AT-protected amino acids by means of imidazolides and triazolides (where Z and Boc represent the protecting groups benzyloxycarbonyl and terf-butoxycarbonyl) ... 

This method is used, for example, for the mild introduction of protecting groups like benzyloxycarbonyl (Z), tert-butoxycarbonyl (Boc) and p-nitrophenylethoxycarbonyl (npeoc). 

The alkoxycarbonyl protecting groups can also be introduced into amines by, triazolides (Table 4—7). With A-tert-butoxycarbonyl-1,2,4-triazole the tert-butoxy-carbonyl protecting group (Boc) is transferred readily onto amino functions of primary amines, trimethylbenzyl ammonium salts of amino acids, or peptides.[ 1965 Alternatively, the Boc group can be transferred with terf-butylphenylcarbonate in the presence of 1,2,4-triazole. In this latter approach the triazolide is presumably formed as an intermediate. ... 

Treatment of the Boc-protected 4-aminoimidazole (75) (prepared via compound (71 R1 = Me, R2 = C02Et) by condensation with t-butoxycarbonyl fluoride in the presence of triethylamine) with trifluoro-... 

The most common method for the preparation of 1,2,3-benzothiadiazoles is the diazotization of 2-aminobenzenethiol. This method was discussed and exemplified in CHEC-II(1996). The method has been extended in recent years to include heterocyclic derivatives. The 2-aminothiophene 79 can be converted into the thienothiadiazole 82 on treatment with sodium nitrite in HC1 but in poor yield (16%). The bis(BOC)-protected derivative 80 or the mono(BOC)-protected derivative 81 when reacted under similar conditions afford product 82 in much higher yields (BOC = /-butoxycarbonyl Scheme 9). The increase in yield is explained in terms of hard and soft electrophilic character. The intermediate in the BOC-protected examples has a soft character allowing attack by sulfur to proceed more easily <1999JHC761>. 

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