Chelation Control in the [3 + 3] Annulation Reaction of Alkoxy-Substituted 1,1-Diacylcyclopropanes with 1,3-Bis(trimethylsilyloxy)-1,3-butadienes. Diversity-Oriented Synthesis of Isochromanes

Abstract

Functionalized arenes were prepared by chelation-controlled [3 + 3] cyclization/cyclopropane opening reactions of 1-trimethylsilyloxy-1,3-butadienes with benzyloxy- or methoxy-substituted 1,1-diacylcyclopropanes. A number of benzyloxy-substituted derivatives were transformed into isochromanes by deprotection and subsequent cyclization. Mixed chromanes-isochromanes were prepared starting with 1,3-bis(silyloxy)-1,3-butadienes containing a remote chloride group.

Self-Condensation of Enaminodiones as a Method for Benzene Ring Construction: Synthesis of Diacyl-Substituted Phenols and Catechols

“…Yield 63% (2.80 g); yellow liquid; IR (ATR) 2934, 2825, 1713, 1600, 1569, 1449, 1265, 1114, 772 cm –1 ; 1 H NMR (500 MHz, CDCl 3 ) δ 3.49 (s, 3H, Me), 4.11 (s, 2H, CH 2 ), 6.49 (s, 1H, CH), 7.46 (dd, J = 7.8 Hz, J = 7.3 Hz, 2H, H-3, H-5 Ph), 7.54 (tt, 1H, J = 7.3 Hz, J = 1.0 Hz, H-4 Ph), 7.97 (dd, J = 7.8 Hz, J = 1.0 Hz, 2H, H-2, H-6 Ph), 15.87 (s, 1H, OH). The analytical data are in accordance with those reported in the literature …”

Adventures in the Chemistry of 1,1-Diacylcyclopropanes

“…The cyclization of dienes 2a – m with benzyloxy-substituted 1,1-diacylcyclopropanes 3h , i afforded salicylates 7a – s in 32–79% yields (Scheme 8 ). 28 Cleavage of the benzyl ether by hydrogenation gave alcohols 8a – k . Base-mediated intramolecular nucleophilic attack of the hydroxyl group to the chloride afforded isochromanes 9a – h .…”

“…The cyclization of dienes 2a-j with methoxysubstituted 1,1-diacylcyclopropanes 3f,g afforded salicylates 6a-p in 30-73% yields (Scheme 7). 28 Relatively low yields were obtained for dienes derived from 1,3diketones in comparison to those derived from ketoesters, presumably due to their lower nucleophilicity. The use of a benzyl rather than a methyl ether allowed the hydroxy group to be used synthetically in follow-up reactions.…”

“…The cyclization of dienes 2a-m with benzyloxysubstituted 1,1-diacylcyclopropanes 3h,i afforded salicylates 7a-s in 32-79% yields (Scheme 8). 28 Cleavage of the benzyl ether by hydrogenation gave alcohols 8a-k. Basemediated intramolecular nucleophilic attack of the hydroxyl group to the chloride afforded isochromanes 9a-h. Van T. Nguyen joined us in the frame of a partnership program with Vietnam National University (VNU) Hanoi. She developed in my group applications of 1,3-bis(trimethylsilyloxy)-1,3-butadiene 10 containing a remote chloride group.…”

4-Diazoisochroman-3-imines: A Class of Metal Carbene Precursors for the Synthesis of Isochromene Derivatives

“…A powerful approach to the formation of the pyran ring of isochromane derivatives is the metal-catalyzed domino transformations of o -alkynylbenzaldehydes and related o -carbonyl arenynes via an isobenzopyrylium (or metal-containing carbonyl ylide) intermediate . The cyclization of β-phenylethanols with aldehydes, the intramolecular nucleophilic substitutions of 2-allylbenzylic alcohols, the oxo-Diels–Alder reaction of o -xylylenes with ketones, and the reaction between ortho-lithiated aryloxiranes and enaminones were also developed for the construction of isochromanes. Because of the importance of isochromane derivatives for their bioactivities, the development of new methods for the construction of this class of compounds is actively being pursued.…”