A mild and efficient methodology concerning I2/TBHP-mediated intermolecular iodoamination of ynamides with amines for the synthesis of [small alpha]-amino-[small beta],[small beta]-diiodo-enamides was developed. This reaction provides the first intermolecular iodoamination of terminal alkynes...
An attractive and novel methodology involving Pd/Cu-catalyzed tandem head-to-tail dimerization/cycloisomerization of terminal ynamides for the synthesis of 3,5-disubstituted oxazolones was developed. Under Pd(PPh3)2Cl2/CuI cooperative catalyzed reaction conditions, it provided efficient access to 5-vinyloxazolones with exceptional functional group tolerance and good chemoselectivity. The control experiments
A Pd-catalyzed, one-pot, two-step synthesis of 2-amidoindoles from ynamides and o-lodoanilines Is reported. A key highlight of this sequence is that after the Sonogashira reaction, intramolecular cyclization to the indole occurs spontaneously without activation of the alkyne.
Ruthenium-Catalyzed Synthesis of 5-Amino-1,2,3-triazole-4-carboxylates for Triazole-Based Scaffolds: Beyond the Dimroth Rearrangement
作者:Serena Ferrini、Jay Zumbar Chandanshive、Stefano Lena、Mauro Comes Franchini、Giuseppe Giannini、Andrea Tafi、Maurizio Taddei
DOI:10.1021/jo502577e
日期:2015.3.6
The 5-amino-1,2,3-triazole-4-carboxylic acid is a suitable molecule for the preparation of collections of peptidomimetics or biologically active compounds based on the triazole scaffold. However, its chemistry may be influenced by the possibility of undergoing the Dimroth rearrangement. To overcome this problem, a protocol based on the ruthenium-catalyzed cycloaddition of N-Boc ynamides with azides has been developed to give a protected version of this triazole amino acid. When aryl or alkyl azides are reacted with N-Boc-aminopropiolates or arylynamides, the cycloaddition occurs with complete regiocontrol, while N-Boc-alkyl ynamides yield a mixture of regioisomers. The prepared amino acids were employed for the preparation of triazole-containing dipeptides having the structural motives typical of turn inducers. In addition, triazoles active as HSP90 inhibitors (as compound 41, IC50 = 29 nM) were synthesized.
Irregularities in the Effect of Potassium Phosphate in Ynamide Synthesis
The yields of ynamides using Hsung's second generation protocol depend substantially on the quality of K3PO4. of K3PO4 from different suppliers were investigated by various techniques, revealing that the use Of pure and anhydrous K3PO4 provides higher ynamide yields in comparison to samples contaminated with hydrates (K3PO4 center dot 1.5H(2)O and K3PO4 center dot 7H(2)O). With high quality K3PO4, a number of ynamides were synthesized in yields of 52-91%. In addition. we report that ynamides can undergo regioselective hydroamination with carbamates.