111681-30-2Relevant academic research and scientific papers
Palladium-catalyzed cross-coupling reaction of azides with isocyanides
Zhang, Zhen,Li, Zongyang,Fu, Bin,Zhang, Zhenhua
supporting information, p. 16312 - 16315 (2015/11/16)
An efficient palladium-catalyzed cross-coupling reaction of azides with isocyanides is developed, providing a general synthetic route to unsymmetric carbodiimides with excellent yields. This method shows a broad substrate scope, including not only aryl azides, but also unactivated benzyl and alkyl azides. Furthermore, from readily available substrates, Pd-catalyzed coupling with a tandem amine insertion cascade to obtain unsymmetric trisubstituted guanidines has been achieved in a one-pot fashion.
Gold metal-catalyzed reactions of isocyanides with primary amines and oxygen: Analogies with reactions of isocyanides in transition metal complexes
Lazar, Mihaela,Angelici, Robert J.
, p. 10613 - 10620 (2007/10/03)
Despite its generally poor catalytic properties, bulk gold metal is observed to catalyze reactions of isocyanides (C≡N-R) with primary amines (H2N-R′) and O2 to give carbodiimides (R-N=C=N-R′) at room temperature and above. Detailed infrared reflection absorption spectroscopic (IRRAS) and kinetic studies show that the reaction occurs by initial η1-adsorption of the isocyanide on the Au surface, which activates the isocyanide to attack by the amine. This attack is the rate-determining step in the catalytic cycle and has characteristics very similar to those of amine reactions with coordinated isocyanides in transition metal complexes. However, the metallic Au surface provides a pathway involving O2 to give the carbodiimide product whereas homogeneous metal ion catalysts give formamidines [HC(=NR)(NHR′)].
The 2-Chloro-3-indenylmethyloxycarbonyl and Benzinden-3-ylmethyloxycarbonyl Base-Sensitive Amino-Protecting Groups. Application to an Inverse Merrifield Approach to Peptide Synthesis
Carpino, Louis A.,Cohen, Beri J.,Lin, Yao-Zhong,Stephens, Kenton E.,Triolo, Salvatore
, p. 251 - 259 (2007/10/02)
Two new base-labile amino-protecting groups, which are more sensitive than the FMOC function, are described: the 2-chloro-3-indenylmethyloxycarbonyl (CLIMOC) and benzinden-3-ylmethyloxycarbonyl (BIMOC) groups.The former was determined to be usable in solvents such as methylene dichloride but not in DMF, the latter in any common solvent including DMF.Key intermediate alcohols 10 and 16 were synthesized from 2-chloroindene (9) and benzindene (14).Treatment of indene with chlorine gave 8, which upon dehydrochlorination with DMF gave 9, which was then converted to 10 by standard procedure involving formylation and reduction.Benzindene was converted to its anion by means of n-butyllithium and the anion hydroxymethylated by gaseous formaldehyde.The alcohols were converted to the corresponding chloroformates and thence to succinimido ester 12 and azidoformate 18 for clean, selective protection of amino acids.Model CLIMOC- and BIMOC-amino acids were synthesized and demonstrated to be useful in carrying out a continous peptide synthesis via a two-polymer (polymeric reagents) approach.The protected amino acids were first loaded onto a phenolic polymer such as 21, and the resulting polymeric active esters were used to acylate an amino acid ester or peptide ester.The resulting protected peptide esters were deblocked via silica-based reagents 6 or 23.The acylation step was then repeated with the next amino acid, and the synthesis continued in the same way until completed.Tetrapeptide 26 and pentapeptide 27 were synthesized in this way via CLIMOC (CH2Cl2) and BIMOC (DMF) protection, respectively.These represent the first examples of clean, continous two-polymer syntheses carried out in a single solvent without the release of any low molecular weight byproducts into the solution. the fi
Preparation of Carbodiimides Using Phase-Transfer Catalysis
Jaszay, Zsuzsa M.,Petnehazy, Imre,Toeke, Laszlo,Szajani, Bela
, p. 520 - 523 (2007/10/02)
A new method is described for the preparation of carbodiimides by dehydration of ureas with arenesulfonyl chlorides under solid-liquid phase-transfer catalytic (PTC) conditions using solid potassium carbonate as a base and a lipophilic quaternary ammonium salt as a catalyst.The method is generally applicable for the synthesis of disubstituted carbodiimides, but is especially useful for unsymmetrically substituted carbodiimides.The basic carbodiimides prepared were identified in the form of the more stable, crystalline quaternary salts.
