Primary amines urethane derivatives

The synthons of oxiranes have also been used in this respect. For example, the reaction of C02 with a-bromoacylophenones in the presence of aliphatic primary amines, in methanol, afforded 3-alkyl-4-hydroxyoxazolidin-2-one derivatives under mild conditions [83a]. However, neither oc-bromoacetophenone nor a-chloroacetophenone afforded any carbamate product, and no urethanes were obtained with aromatic or aliphatic secondary amines. The proposed mechanism involved, as the first step, the formation of a 3-alkyl-2-methoxy-2-phenyloxirane intermediate, which reacted with alkylammonium carbamate to give the oxazo-lidone product (Scheme 6.16). This synthetic protocol was successfully applied to the synthesis of bis(oxazolidin-2-one) derivatives by reactions of 2-methoxy-3,3-dimethyl-2-phenyloxirane or a-bromoisobutyrophenone with C02 and aliphatic a,G)-diamines [83b],... 

That product (17) is then converted to the activated A -hydoxysuccinimide derivative 18 as in the case of the monocyclic furan. Reaction with the primary amine 10 used to prepare amprenavir then leads to the urethane (19). Reduction of the nitro group then affords darunavir" (20). 

The phenylselenenyl chloride induced intramolecular ring closure of ro-aminoalkenes can be utilized in the synthesis of nitrogen heterocycles. Olefinic primary amines do not cyclize readily in this reaction, while urethane derivatives and secondary amines cyclize according to the following scheme55 56. 

A simple method for the preparation of primary amines from aliphatic halides involves the treatment of the halide with KOCN in alcohol to give the urethane which is hydrolyzed to the amine. In general the yields are high. A novel conversion in which tetrakis(dimethylamino) titanium converts carboxylic acids and their common derivatives in orthoamides and ketene N,N-acetals in good yields is described. ... 

Thus, as outlined in Scheme 4.4.9, a chloroformate-functionalised polystyrene resin 284 was treated individually with a wide range of anthranilic acid derivatives 285 in the presence of Hunig s base to give the urethane-linked system 286. Structurally diverse primary amines were readily coupled to the free carboxylic acid of 286 using standard PyBOP conditions to give anthranilamides 287. Thermal treatment of 287 caused the amide nitrogen to cyclise onto the... 

Isocyanates and isothiocyanates react with primary amines to give urea and thiourea derivatives respectively. However, isocyanates react quite readily with water and alcohols to give urethanes. For this reason they are generally replaced by the less reactive isothiocyanates. However, a-naphthylisocyanate was recommended for the determination of lipids with a hydroxyl function [214] and may also find application in amino acid analysis. 

Chemical. A large number of chitin and chitosan derivatives have been synthesized through modification of the primary (C-6) and secondary (C-3) hydroxyl groups present on each repeat imit, including amine (C-2) functionality existing on deacetylated imits (31). Reactions typical of hydroxyl and amine groups (such as acylations with acid chlorides and anhydrides) including urethane and urea formation respectively, are feasible with isocyanates. The primary amine can be quatemized by alkyl iodides or converted to an imine with a variety of aldehydes and ketones that can subsequently be reduced to an N-alkylated derivative. Chitin and chitosan are reactive with a variety of alkyl chlorides after treatment with concentrated NaOH. Important derivatives such as carboxymethylated chitin and chitosan are commonly produced in this manner with the addition of sodium chloroacetate. 

Aromatic nitro groups Aromatic rings N-oxides Alkyl hydrazines Alkyl aldehydes N-methyl derivatives Monoalkenes p-Haloethyl mustards N-Chloroamines Alkyl N-nitrosoamines Alkyl esters of either phosphoric or sulfonic adds Aromatic mono- and dialkylamino groups Aromatic azo groups (because of possible reduction to aromatic amines) Aromatic and aliphatic aziridinyl derivatives Aromatic and aliphatic substituted primary alkyl halides Aromatic amines (including their N-hydroxy derivatives and the derived esters Propriolactones and propriosultones Derivatives of urethane (carbamates) Aliphatic and aromatic epoxides... 

Scheme 4.4). Other reagents useful for terminal guanidinylation of primary and secondary amines have been reported, in which 5-methylisothiourea [15], protected guanidine [16], pyrazole-l-carboxamidine [17] and benzotriazole-1-carboxamidine derivatives [18] are explored. A solid support-linked guanidinylating reagent, consisted of a urethane-protected... 

The synthesis of benzyloxycarbonyl (31) derivatives by the amino-lysis of various active esters of benzyl carbonate has been reported The use of JV-hydroxypiperidyl methoxybenzyl carbonate and JV-hydroxypiperidyl f-butyl carbonate for the synthesis of -methoxy-benzyloxycarbonyl and f-butyloxycarbonyl (45) derivatives, respectively, has been described The benzhydryloxycarbonyl group (35) could be removed by the action of boron trifluoride in glacial acetic acid . The use of easily cleaved, optically active, protecting groups of the urethane type for the resolution of racemic primary and secondary amines was reported . 

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