- Synthesis and reactivity of N -alkyl carbamoylimidazoles: Development of N -methyl carbamoylimidazole as a methyl isocyanate equivalent
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A high-yielding synthesis of N-methyl carbamoylimidazole from 1,1-carbonyldiimidazole (CDI) and MeNH3Cl is described. The product is a crystalline, readily storable, water-stable compound that reacts as a methyl isocyanate (MIC) substitute. Reaction of N-methyl carbamoylimidazole in the presence of a base such as triethylamine occurs with nucleophiles such as amines, protected and unprotected amino acids, thiols and alcohols. The product N-methylureas, carbamates and thiocarbamates are obtained in good to excellent yields, with reactions occurring in either organic solvents or water. The protocol for the synthesis of N-methyl carbamoylimidazole is both scalable and general, occurring in quantitative yield at scales ranging from 300 mg to 20 g. The success of this method relies upon the reaction of CDI with the ammonium salt rather than the free amine, resulting in a significant improvement in the yield of N-methyl carbamoylimidazole. The reaction presumably involves a proton transfer from MeNH3Cl to the CDI, which results in the release of MeNH2 with simultaneous activation of the CDI as its protonated form. Other primary ammonium hydrochloride salts, including protected α-amino acid salts, give excellent yields of the corresponding N-alkyl carbamoylimidazoles and serve as alkyl isocyanate surrogates. The resultant N-alkyl carbamoylimidazoles can be converted to ureas in high yields without the formation of intermediary isocyanates.
- Duspara, Petar A.,Islam, Md. Sadequl,Lough, Alan J.,Batey, Robert A.
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p. 10362 - 10368
(2013/01/15)
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- A convergent asymmetric synthesis of a growth hormone secretagogue
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Described herein is a convergent asymmetric synthesis of growth hormone secretagogue (GHS) suitable for large-scale preparations. Key features include: (1) an improved method for α-iodination of a lactam; (2) a novel synthesis of a disubstituted urea usin
- Zheng, Nan,Armstrong III, Joseph D.,Eng, Kan K.,Keller, Jennifer,Liu, Tom,Purick, Robert,Lynch, Joseph,Hartner, Frederick W.,Volante
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p. 3435 - 3446
(2007/10/03)
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- Biphenyl substituted dipeptide analogs promote release of growth hormone
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There are disclosed certain compounds identified as substituted dipeptide analogs which promote the release of growth hormone in humans and animals. This property can be utilized to promote the growth of food animals to render the production of edible meat products more efficient, and in humans, to increase the stature of those afflicted with a lack of a normal secretion of natural growth hormone. Growth promoting compositions containing such substituted dipeptide analogs as the active ingredient thereof are also disclosed.
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- A novel synthesis of disubstituted ureas using titanium(IV) isopropoxide and sodium borohydride
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This paper describes a high yield preparation of unsymmetrically disubstituted ureas by a titanium(IV) isopropoxide/sodium borohydride mediated reductive amidation of aromatic aldehydes with monosubstituted ureas.
- Armstrong III, Joseph D.,Wolfe, Chad N.,Keller, Jennifer L.,Lynch, Joseph,Bhupathy,Volante,De Vita, Robert J.
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p. 1531 - 1532
(2007/10/03)
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