A Method to Access Highly Functionalized Dibenzobicyclo[3.2.1]octadienones: Application to the Construction of the 6/6/5/6/6 Carbon Skeleton of Rubialatin A

Abstract

The dibenzobicyclo[3.2.1]­octadienone scaffold, which has been found in naphthocyclinones, engelharquinones, rubialatin A, etc., has been synthesized under mild transition metal-free conditions by aryne insertion reaction with 2-keto-1,3-indandiones. The application of this methodology has been demonstrated for the synthesis of the 6/6/5/6/6 scaffold of rubialatin A. 1H NMR experimental studies confirm that the reaction proceeds through the formation of benzocyclobutane followed by a 7-member carbocycle ring.

Cascade Nucleophilic Addition–Cyclic Michael Addition of Arynes and Indoles Bearing Michael Acceptor: A Strategy to Construct Pyrroloacridines and Study of Their Physicochemical Properties

“…Noteworthy to mention here that the naphthalene-derived aryne precursors provided 4 to 5 fused rings containing 6 H -pyrrolo­[3,2,1- de ]­acridine compounds in good yield (Scheme ). As expected, regioisomeric mixtures (1:1) of 3v were obtained when we have used 4-methyl substituted aryne precursors …”

“…However, people witnessed a flourishing advance in aryne chemistry, which was mainly attributed to the exponential applications of Kobayashi’s method in the past 20 years . In connection with our ongoing research interest in developing novel and efficient methodologies by using aryne intermediates, we were attracted to utilizing substituted indoles having a suitable Michael acceptor to form a six-membered ring after the reaction with aryne. A wide variety of cascade reactions have been employed with aryne as one of the active ingredients.…”

“…As expected, regioisomeric mixtures (1:1) of 3v were obtained when we have used 4-methyl substituted aryne precursors. 14 This success encouraged us to functionalize 6H-pyrrolo-[3,2,1-de]acridine compounds into various derivatives, as shown in Scheme 4. The di-keto functionality present in 3n was reduced to the corresponding secondary alcohols by a borane reagent, BH 3 •SMe 2 in THF provided compound 4 in 62% yield (dr 1:1 by NMR).…”

Synthesis of Highly Functionalized Spirocycles and Pentafulvene‐Containing Dyes Involving 2‐(2′‐ketoalkyl)‐1,3‐indandiones

“…Therefore, synthesizing functionalized spirocyclic systems under simple and mild conditions, especially by using a catalytic amount of organic bases, has always been promising and sustainable. In connection with our ongoing research interest in developing novel and efficient synthetic methodologies involving 2‐phenacyl‐1,3‐indandione with arynes, [7] we were attracted to using commercially available and cheap dimethyl acetylenedicarboxylate (DMAD) as a coupling partner, as it has been well exploited in many carbon–carbon bond formation reactions [8] . In contrast with arynes, DMAD is an electron‐deficient alkyne diester in which the ester groups are in conjugation with a C≡C triple bond.…”

Electronically-controlled diastereoselective synthesis of spirocycles via [4 + 2] cycloaddition of 2-arylidene-1-indenones with benzyne

“…dibenzo[ a , d ]cycloheptanoids as a major product and dibenzo[ a , c ]anthracene-9,14-diones as a minor one. 12 Intrigued by this result, we wondered whether reacting the benzyne source with 2-arylidene-1-indenones might produce a fascinating result. Gratifyingly, we received two different kinds of spirocycles under altered electronic settings.…”