The art of total synthesis through cascade reactions

Nicolaou, K. C.; Chen, Jason S.

doi:10.1039/b903290h

Cited by 694 publications

(160 citation statements)

References 44 publications

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“…[38] The catalyst was used to promote the etherification of benzyl alcohols 26 by using the nucleophilic alcohol as the solvent, at 100°C, and these Lewis acid catalysts can be used in cascade-type reactions. [39] Scheme 9. Etherification of benzylic alcohols by solid Lewis acid catalyst Sn-beta.…”

Section: Solid Brønsted Acidsmentioning

confidence: 99%

Direct Nucleophilic S_N1‐Type Reactions of Alcohols

et al. 2010

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In 2005, the ACS Green Chemistry Institute (GCI) and the global pharmaceutical corporations developed the ACS GCI Pharmaceutical Roundtable to encourage the development of green chemistry and green engineering in the pharmaceutical industry. The Roundtable has established a list of key research areas including the direct nucleophilic reactions of alcohols. The substitution of activated alcohols is a frequently used approach for the preparation of active pharmaceutical ingredients. Alcohols are transformed into the reactive halides or sulfonate esters, thereby allowing their reaction with nucleophiles. Although the direct nucleophilic substitution of an alcohol should be an attractive process, as one of the byproducts from the reaction yields water, hydroxide is a poor leaving group that hinders the reaction. Recently, the direct substitution of allylic, benzylic, and tertiary alcohols has been achieved through an SN1 reaction with catalytic amounts of Brønsted or Lewis acids. In this review, the approaches leading to a greener process are examined in detail, and the advances achieved to date in this important transformation are presented.

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Section: Solid Brønsted Acidsmentioning

confidence: 99%

Direct Nucleophilic S_N1‐Type Reactions of Alcohols

et al. 2010

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“…We define a natural product as a compound that is present within or in the immediate vicinity of the producing organism. As such, many compounds that are spontaneously formed from reactive intermediates, for instance via cascade reactions [29][30][31][32][33][34] , can indeed be classified as natural products. Our hypothetical starting material O-Methyl bipinnatin J (7), however, has been suspected to be an isolation artefact as methanolysis of bipinnatin J (1) and of kallolide (2) is a very facile process 18 .…”

Section: Discussionmentioning

confidence: 99%

Photochemical formation of intricarene

et al. 2014

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Sunlight is the ultimate driver of biosynthesis but photochemical steps late in biosynthetic pathways are very rare. They appear to play a role in the formation of certain furanocembranoids isolated from Caribbean corals. One of these compounds, intricarene, has been suspected to arise from an intramolecular 1,3-dipolar cycloaddition involving an oxidopyrylium. Here we show, by a combination of experiments and theory, that the oxidopyrylium forms under photochemical conditions and that its cycloaddition occurs via a triplet state. The formation of a complex by-product can be rationalized by another photochemical step that involves a conical intersection. Our work raises the question whether intricarene is biosynthesized in the natural habitat of the corals or is an artefact formed during workup. It also demonstrates that the determination of exact irradiation spectra, in combination with quantum chemical calculations, enables the rationalization of complex reaction pathways that involve multiple excited states.

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“…62 Neste mesmo número especial, o grupo de Nicolaou traz de novo a sua visão sobre as reações em cascata. 63 Em princípio, as reações dominó envolvem a formação do dieno ou a liberação do dienófilo durante uma sequência, e normalmente seria a última reação já que o cicloexeno formado não é propício a efetuar mais reações químicas.…”

Section: Reações De Diels-alder Em Dominóunclassified