Tosylhydrazones. V. Reaction of Tosylhydrazones with Alkyllithium Reagents. A New Olefin Synthesis.
01 Oct 1967-Journal of the American Chemical Society (American Chemical Society)-Vol. 89, Iss: 22, pp 5734-5735
About: This article is published in Journal of the American Chemical Society.The article was published on 1967-10-01. It has received 193 citations till now.
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TL;DR: In this review, cyclization reactions based on N-tosylhydrazones as substrates are discussed and a series of cyclic compounds, including aromatic and non-aromatic ring systems, are demonstrated to be easily constructed by cyclizations with N-TosylHydrazones.
Abstract: N-Tosylhydrazones have recently emerged as useful synthons in a variety of transition-metal-catalyzed and transition-metal-free reactions, which affords novel methodologies for the formation of carbon–carbon and carbon–heteroatom bonds. In this context, it has been found that N-tosylhydrazones can be used as versatile building blocks in the construction of a range of cyclic compounds. In this review, cyclization reactions based on N-tosylhydrazones as substrates are discussed. A series of cyclic compounds, including aromatic and non-aromatic ring systems, are demonstrated to be easily constructed by cyclizations with N-tosylhydrazones.
235 citations
TL;DR: Dimethylhydrazone (DMH's) 6−10 von enolisierbaren Aldehyden und Ketonen konnen with n-Butyllithium and/oder Lithium-diisopropylamid in Tetrahydrofuran quantitativ in α-Stellung metalliert werden as mentioned in this paper.
Abstract: Dimethylhydrazone (DMH's) 6–10 von enolisierbaren Aldehyden und Ketonen konnen mit n-Butyllithium und/oder Lithium-diisopropylamid in Tetrahydrofuran quantitativ in α-Stellung metalliert werden. Die so erhaltenen Lithiumderivate 11–14 sind hochreaktive Kohlenstoffnucleophile. Ihre Verwendung als Enolataquivalente wird uber die Sequenz Carbonylverbindung, DMH-Derivat. Metallierung, Reaktion mit Alkylhalogeniden (→ 16, 18, 19) und Spaltung zur α-substituierten Carbonylverbindung (17) an einer Anzahl von Beispielen demonstriert. Die Alkylierungen erfolgen, von Spezialfallen abgesehen, regiospezifisch am weniger substituierten Kohlenstoffatom. Cyclohexanonderivate werden stereoselektiv axial alkyliert, was zur Darstellung von trans-disubstituierten Cyclohexanonen ausgenutzt wird. Zur quantitativen Spaltung der Dimethylhydrazone zuruck zu den Carbonylverbindungen unter milden Bedingungen (pH 7, Raumtemperatur) wurde eine neue oxidative Hydrolyse entwickelt. Die Vorteile der Methode werden kurz diskutiert.
167 citations
TL;DR: This review highlights approximately 20 all carbon cage containing pharmaceuticals, ranging in structure from bicyclo[2.2.1] through to adamantane, including some in the top-selling pharmaceutical bracket.
Abstract: Numerous variations on structural motifs exist within pharmaceutical compounds that have entered the clinic. These variations have amounted over many decades based on years of drug development associated with screening natural products and de novo synthetic systems. Caged (or bridged) bicyclic structural elements offer a variety of diverse features, encompassing three-dimensional shape, and assorted pharmacokinetic properties. This review highlights approximately 20 all carbon cage containing pharmaceuticals, ranging in structure from bicyclo[2.2.1] through to adamantane, including some in the top-selling pharmaceutical bracket. Although, a wide variety of human diseases, illnesses and conditions are treated with drugs containing the bicyclic motif, a common feature is that many of these lipophilic systems display CNS and/or neurological activity. In addition, to an extensive overview of the history and biology associated with each drug, a survey of synthetic methods used to construct these entities is presented. An analysis section compares natural products to synthetics in drug discovery, and entertains the classical caged hydrocarbon systems potentially missing from the clinic. Lastly, this unprecedented review is highly pertinent at a time when big pharma is desperately trying to escape flatland drugs.
154 citations