Synthesis of Heterocycles via Gold and Silver-Catalyzed Cycloadditions and Carboalkoxylations of Alkynes

• Main Author: 陳俊豪
• Other Authors: 劉瑞雄
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/03382437965239540398

博士 === 國立清華大學 === 化學系 === 102 === Chapter I We report the Ag(I)-catalyzed tandem 6-exo-dig-azacyclization/[3+2] cycloaddition cascades on 1-tosylhydrazon-4-oxy-5-ynes to form complicated azacyclic products efficiently. Control experiments exclude the intermediacy of isoquinolinium species because of its poor activity in the cycloaddition with enol ether. We hypothesize that the [3+2] dipolar cycloadditions likely occur on non-aromatic zwitterionic intermediates. Chapter II We report herein the gold-catalyzed cyclization/oxidative [3+2] cycloadditions of 1,5-enynes with nitrosobenzenes. Notably, nitrosobenzenes not only provide two-atom building units, but also lead to the alkyne oxidation. Such a reaction pattern is unprecedented in metal-catalyzed cycloadditions of 1,n-enynes. V Chapter III We have developed a formal [2+2+2] cycloaddition of 1,5-enyne with aldehydes or nitrosobenzenes to give cyclobutene derivatives. This reaction involves the cyclopropyl gold carbene intermediate, which is trapped by aldehydes or nitrosobenzenes. Chapter IV In this work, we demonstrate the effects of the counter anions (X) of P(t-Bu)2(o-biphenyl)X and water, to control the regioselective formation of 1- or 3-substituted 2-methoxy-1-H-indenes from the same VI 2-alkynylbenzyl ethers; these two indenyl ethers can be oxidative cleaved by O3 to give two distinct highly oxygenated products, thus highlighting the synthetic utility.