- Synthesis of cyclic guanidines via Pd-catalyzed alkene carboamination
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A new approach to the synthesis of substituted 5-membered cyclic guanidines is described. Palladium-catalyzed alkene carboamination reactions between acyclic N-allyl guanidines and aryl or alkenyl halides provide these products in good yield. This method
- Zavesky, Blane P.,Babij, Nicholas R.,Fritz, Jonathan A.,Wolfe, John P.
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- A New synthetic protocol for the preparation of carbodiimides using a hypervalent iodine(III) reagent
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A new, simple, and efficient preparation of symmetrical and unsymmetrical carbodiimides from the corresponding thioureas via dehydrosulfurization using a hypervalent iodine(III) reagent is described. The oxidation afforded carbodiimides in excellent yields and high selectivity. A possible mechanism for the transformation is proposed. Georg Thieme Verlag Stuttgart New York.
- Zhu, Chenjie,Xu, Dan,Wei, Yunyang
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- Manganese-catalyzed cleavage of a carbon-carbon single bond between carbonyl carbon and α-carbon atoms of ketones
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Singled out: Treatment of ketones with carbodiimides in the presence of a catalytic amount of either [{HMn(CO)4}3] or [Mn 2(CO)10] gave amides in good to excellent yields. In this reaction, the carbon-carbon single bond of a ketone is cleaved efficiently. The reaction also proceeded by using isocyanates instead of carbodiimides. Copyright
- Kuninobu, Yoichiro,Uesugi, Tadamasa,Kawata, Atsushi,Takai, Kazuhiko
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- A facile method for the preparation of carbodiimides from thioureas and (Boc)2O
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A concise method for the preparation of carbodiimides from thioureas using di-tert-butyl dicarbonate [(Boc)2O] as the dehydrosulfurizative reagent has been developed. Using DMAP as the catalyst, a variety of symmetric and asymmetric 1,3-diaryl thioureas were converted into the corresponding carbodiimides efficiently in a short time.
- Wu, He,Sun, Yan-Fang,Zhang, Chen,Miao, Chun-Bao,Yang, Hai-Tao
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supporting information
p. 739 - 742
(2018/01/27)
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- Pushing back the limits of hydrosilylation: Unprecedented catalytic reduction of organic ureas to formamidines
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Pushing back the limits: A novel catalytic transformation has been designed to prepare formamidine derivatives by reduction of substituted ureas with hydrosilanes. Simple iron catalysts based on commercially available iron salts and phosphine ligands prov
- Pouessel, Jacky,Jacquet, Olivier,Cantat, Thibault
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p. 3552 - 3556
(2014/01/06)
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- Regioselective multicomponent sequential synthesis of hydantoins
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The development of new practical and green methods for the synthesis of small heterocycles is an attractive area of research due to the well-known potential of heterocyclic small molecule scaffolds in the drug discovery process. Herein we report a one-pot, three-component sequential procedure for the synthesis of diversely 1,3,5- and 1,3,5,5-substituted hydantoins, in high yields and very mild conditions, using readily accessible starting materials such as azides, iso(thio)cyanates and substituted α-halo-acetic carboxylic acids. This methodology is especially convenient for the synthesis of spiro-hydantoins, which are particularly interesting bioactive compounds in medicinal chemistry. The Royal Society of Chemistry 2012.
- Olimpieri, Francesca,Bellucci, Maria Cristina,Marcelli, Tommaso,Volonterio, Alessandro
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p. 9538 - 9555
(2013/01/16)
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- O-Iodoxybenzoic acid mediated oxidative desulfurization of 1,3-disubstituted thioureas to carbodiimides
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An efficient and mild oxidative desulfurization procedure using o-iodoxybenzoic acid has been developed for the synthesis of carbodiimides starting from easily synthesizable 1,3-disubstituted thioureas.
- Chaudhari, Pramod S.,Dangate, Prasad S.,Akamanchi, Krishnacharya G.
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supporting information; experimental part
p. 3065 - 3067
(2011/02/25)
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- A greener synthetic protocol for the preparation of carbodiimide
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A new and facile preparation of symmetrical and unsymmetrical 1,3-diaryl and aryl-alkyl carbodiimides via a dehydrosulfurisation of their corresponding thioureas is described. Herein, the classical method of oxidative desulfurisation of thiourea to carbodiimide involving toxic heavy metal oxides (HgO) has been replaced with an easily available, cost-effective and environmentally benign reagent, iodine. Simple reaction conditions, easy purification of the products and high yields are important attributes of the present methodology and perhaps the best alternative from a green chemistry perspective. The only limitation to this method however, is in the preparation of 1,3-dialkyl substituted carbodiimide.
- Ali, Abdur Rezzak,Ghosh, Harisadhan,Patel, Bhisma K.
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experimental part
p. 1019 - 1021
(2010/04/02)
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- Copper(II) acetate/oxygen-mediated nucleophilic addition and intramolecular C-H activation/C-N or C-C bond formation: One-pot synthesis of benzimidazoles or quinazolines
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Diarylcarbodiimides or benzylphenylcarbodiimides are converted to 1,2-disubstituted benzimidazoles or 1,2-disustituted quinazolines via addition/intramolecular C-H bond activation/C-N or C-C bond forming reaction using copper(II) acetate/oxygen [Cu(OAc)2/O2] as the oxidant at 100°C in one-pot cascade procedure. Copyright
- He, Hua-Feng,Wang, Zhi-Jing,Bao, Weiliang
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supporting information; experimental part
p. 2905 - 2912
(2010/12/29)
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- Catalytic conversion of isocyanates to carbodiimides by cyclopentadienyl manganese tricarbonyl and cyclopentadienyl iron dicarbonyl dimer
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Isocyanates are catalytically converted to the corresponding carbodiimides in the presence of low valent transition metal complexes. The best conversions and yields were accomplished using [(C5R5)Fe(CO)2]2 (R = H or Me) or MeCpMn(CO)3 as catalysts.
- Rahman, A.K. Fazlur,Nicholas, Kenneth M.
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p. 6002 - 6004
(2008/02/10)
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- Heterocumulene metathesis by iridium guanidinate and ureylene complexes: Catalysis involving reversible insertion to form six-membered metallacycles
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The four-membered metallacycles Cp*Ir((NAr)2C=Z) have been prepared for Z = NAr and Z = O. These complexes undergo facile exchange with free heterocumulenes. This exchange process can be employed to effect the rapid, catalytic metathesis of aryl carbodiimides at room temperature and the metathesis of aryl carbodiimides with aryl isocyanates at slightly elevated temperature. The exchange process appears to proceed via a novel associative mechanism involving ring expansion to form a six-membered metallacycle rather than cycloreversion to give an imido complex. Observation of key intermediates and the results of crossover experiments support this hypothesis. Copyright
- Holland, Andrew W.,Bergman, Robert G.
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p. 9010 - 9011
(2007/10/03)
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- Preparation and intramolecular cyclization of bis(carbodiimides). Synthesis and X-ray structure of 1,3-diazetidine-2,4-diimine derivatives
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Aza-Wittig reactions of bis(iminophosphorane) 1 derived from 2,2'- diazidobiphenyl with aromatic isocyanates provided dibenzo[d,f]-1,3- diazetidino[1,2-a]diazepine derivatives 2 in moderate yields. Similar results can be achieved from the reaction of 2,2-bis(isothiocyanato)biphenyl 4 with aryliminophosphoranes. Treatment of bis(isothiocyanate) 4 with arylamines and further dehydrosulfurization of the resulting bis(thioureas) leads to the seven-membered ring guanidines 8. N-2(2'-Azido)biphenyl-N'-arylcarbodiimides 13 react with 1 equiv of triphenylphosphane to give zwitterionic compounds 15, which undergo either hydrolytic cleavage to afford the guanidines 8 or react with 1 equiv of aromatic isocyanates to provide 2. Cross-experiments suggest that the conversion 15 ← 2 takes place through a nonisolable bis(carbodiimide) that undergoes an intramolecular [2 + 2] cycloaddition at the final step. The reaction of bis(iminophosphorane) 1 with an excess of carbon dioxide leads to a mixture of the tricyclic 1,3-diazetidine derivative 6 and the 14-membered cyclic bis(carbodiimide) 23, which decomposes by thermal treatment. Compound 6 can also be obtained along with the seven- membered cyclic urea derivatives 24 from the reaction of bis(iminophosphorane) 1 with the carbon dioxide source Boc2O/DMAP system. A comprehensive mechanistic scheme for the aza-Wittig reactions studied is conveniently presented. The molecular and crystal structures of 1-(4- methoxyphenyl)-2-(4-methoxyphenyl)iminodibenzo[d,f]-1,3-diazetidino[1,2- a]diazepine (2c) and [a,c]bis[dibenzo[d,f][1,3]diazepino]-1,3-diazetidine (6) have been determined by X-ray analysis.
- Alajarin,Molina,Sanchez-Andrada,Foces-Foces
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p. 1121 - 1130
(2007/10/03)
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