synthesis of polycyclic ring systems using transition metal catalyzed cyclizations of diazo alkynyl ketones合成多环的环系统使用过渡金属催化环化重氮炔基酮.pdf

Molecules 2001, 6, 1–12 molecules ISSN 1420-3049 Review Synthesis of Polycyclic Ring Systems Using Transition Metal Catalyzed Cyclizations of Diazo Alkynyl Ketones ‡ Albert Padwa* Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA * To whom correspondence should be addressed; e-mail: chemap@. ‡ Presented at the 4th Electronic Conference on Synthetic Organic Chemistry, September 1-30, 2000, (Paper A0002). Received: 3 November 2000 / Accepted: 6 November 2000 / Published: 22 December 2000 Abstract: The rhodium(II)-catalyzed reaction of α-diazo ketones bearing tethered alkyne units represents a new and useful method for the construction of a variety of substituted cyclopentenones. The process proceeds by addition of the rhodium-stabilized carbenoid onto the acetylenic π-bond to give a vinyl carbenoid intermediate. The resulting rhodium complex undergoes a wide assortment of reactions including cyclopropanation, 1,2- hydrogen migration, CH-insertion, addition to tethered alkynes and ylide formation. When 2-alkynyl-2-diazo-3-oxobutanoates were treated with a Rh(II)-catalyst, furo[3,4-c]furans were formed in excellent yield. Keywords:.rhodium, catalyst, diazo, ketone, alkyne, cyclization, CH-insertion, ylide, furo[3,4-c]furans Introduction The chemistry of transition metal carbene complexes has been a subject of intense activity over the past two decades [1]. Current interest in this field stems from the role of metal carbenes in alkene metathesis [2], in alkene and alkyne polymerization [3]