Tandem azidination– and hydroazidination–Huisgen [3 + 2] cycloadditions of ynamides. Synthesis of chiral amide-substituted triazoles
作者:Xuejun Zhang、Richard P. Hsung、Lingfeng You
DOI:10.1039/b606680a
日期:——
Tandem azidination- and hydroazidination-Huisgen [3 + 2] cycloadditions of ynamides are described here. These processes are regioselective and chemoselective, leading to the synthesis of chiral amide-substituted triazoles.
Copper Sulfate-Pentahydrate-1,10-Phenanthroline Catalyzed Amidations of Alkynyl Bromides. Synthesis of Heteroaromatic Amine Substituted Ynamides
作者:Yanshi Zhang、Richard P. Hsung、Michael R. Tracey、Kimberly C. M. Kurtz、Eymi L. Vera
DOI:10.1021/ol049827e
日期:2004.4.1
A practical cross-coupling of amides with alkynyl bromides using catalytic CuSO(4)(.)5H(2)O and 1,10-phenanthroline is described here. This catalytic protocol is more environmentally friendly than the use of CuCN or copper halides and provides a general entry for syntheses of ynamides including various new sulfonyl and heteroaromatic amine substituted ynamides. Given the interest in ynamides, this N-alkynylation of amides should be significant for the future of ynamides in organic synthesis.
A Copper-Catalyzed C−N Bond Formation Involving sp-Hybridized Carbons. A Direct Entry to Chiral Ynamides via N-Alkynylation of Amides
作者:Michael O. Frederick、Jason A. Mulder、Michael R. Tracey、Richard P. Hsung、Jian Huang、Kimberly C. M. Kurtz、Lichun Shen、Christopher J. Douglas
DOI:10.1021/ja021304j
日期:2003.3.1
A copper-catalyzed new C-N bond formation involving a sp-hybridized carbon is described here leading to a facile entry for syntheses of chiral ynamides. This direct N-alkynylation of amides should have a significant impact on the future development of synthetic methodologies employing ynamides.
Synthesis of α-Keto-Imides via Oxidation of Ynamides
作者:Ziyad F. Al-Rashid、Whitney L. Johnson、Richard P. Hsung、Yonggang Wei、Pei-Yuan Yao、Renhei Liu、Kang Zhao
DOI:10.1021/jo8015067
日期:2008.11.21
A de novo preparation of alpha-keto-imides via ynamide oxidation is described. With a number of alkyne oxidation conditions screened, a highly efficient RuO2-NaIO4 mediated oxidation and a DMDO oxidation have been identified to tolerate a wide range of ynamide types. In addition to accessing a wide variety of a-keto-imides, the RuO2-NaIO4 protocol provides a novel entry to the vicinal tricarboryl motif via oxidation of push-pull ynamides, and imido acylsilanes from silyl-substituted ynamides. Chemoselective oxidation of ynamides containing olefins can be achieved by using DMDO, while the RuO2-NaIO4 protocol is not effective. These studies provide further support for the synthetic utility of ynamides.
Highly Substituted 2-Amido-furans From Rh(II)-Catalyzed Cyclopropenations of Ynamides
作者:Hongyan Li、Richard P. Hsung
DOI:10.1021/ol901860b
日期:2009.10.1
Rh(II)-catalyzed cyclopropenations of ynamides are described. Although an actual amido-cyclopropene intermediate may not be involved, these reactions provide a facile entry to highly substituted 2-amido-turans, thereby formerly constituting a [3 + 2] cycloaddition. An application of these de novo 2-amido-turans in N-tethered intramolecular [4 + 2] cycloadditions is also illustrated, leading to dihydroindoles and tetrahydroquinolines.