Studies on intramolecular alkylation. V. Intramolecular alkylation of the aromatic ring in tetrahydronaphthyl diazomethyl ketones

Abstract

The acid-catalysed reactions in weakly nucleophilic environments of 2-diazoacetyl-l,2,3,4-tetrahydronaphthalene (ll), of 6-diazoacetyl-5,6,7,8-tetrahydro-2-naphthol (2), of 6-diazoacetyl-5,6,7,8- tetrahydro-2-naphthyl methyl ether (3) and its 2,8 and 2,5 isomers (14) and (17), and of 6-diazo- acetyl-5,6,7,8-tetrahydro-6-trifluoroacetoxy-2-naphthyl methyl ether (9) have been studied. Several of the spirocyclohexa-2,5-dienone derivatives prepared thus, (4), (8) and (16), provide potential intermediates or models for the synthesis of tetracyclic diterpenoids.

Protecting‐Group‐Free Formal Synthesis of Platensimycin

“…Quite recently, intermediate 2 has also been prepared in racemic form by the Snider group (seven steps + equilibration + one step for conversion of a diastereomer, 32 %). [5] We report a novel route to 2 that starts from known compound 7 (Scheme 2), [6] which is readily available in multigram quantities from inexpensive 6-methoxy-1-tetralone (4) in 50 % overall yield. [6,7] Intermediates 5, 6, and 7 are crystalline and can be isolated without any chromatography.…”

“…[5] We report a novel route to 2 that starts from known compound 7 (Scheme 2), [6] which is readily available in multigram quantities from inexpensive 6-methoxy-1-tetralone (4) in 50 % overall yield. [6,7] Intermediates 5, 6, and 7 are crystalline and can be isolated without any chromatography. The catalytic hydrogenation of 5 to 6 might be performed with a chiral catalyst, so that 7 should also be available as either enantiomer.…”

Recent Advances on Platensimycin: A Potential Antimicrobial Agent

“…Interestingly, (27) and (28) both could be converted into alkene (30) by treatment with Tf 2 O treatment in pyridine and additional required treatment with 1M HCl for (28). Finally, the key intermediate ((±)-6) was obtained in two-step through SeO 2 allylic oxidation under MW irradiation and MnO 2 oxidation of alkene (30) Mulzer and co-workers [39] also reported a novel route to racemic (6) based on a known intermediate (33) (Scheme 6) described in 1974, which was readily obtained from commercially available 6-methoxyl-1-tetralone (31) in 50% overall yield in seven steps [40]. Methylation of (33) followed by allylic bromination produced bromide (34) stereoselectively, which was base-induced cyclization to tetrahydrofuran (35).…”

Fortschritte in der Chemie und Biologie natürlicher Antibiotika

“…Dieses Keton war bereits von Mander et al durch intramolekulare Alkylierung einer aromatischen Vorstufe mit einer Diazoketongruppe hergestellt worden. [238] Tiefenbacher und Mulzer gewannen das Diazoketon 388 durch Hydrierung der ungesättigten Carbonsäure 387, [237] die in drei Schritten aus dem Tetralon 386 erhalten wurde (Schema 56 b). [239] Die Reduktion wurde unter achiralen Bedingungen durchgeführt, weshalb 388 als Racemat entstand, aber die Autoren wiesen darauf hin, dass dieser Schritt für eine asymmetrische Induktion geeignet sein könnte.…”

“…Synthese des Platensimycinkerns 310 (a) und asymmetrische Diels-Alder-Reaktion mit einem 1-Alkylcyclopentadien (b) . [228,230] die stereokontrollierte Einführung einer Doppelbindung, [236] [238] Tiefenbacher und Mulzer gewannen das Diazoketon 388 durch Hydrierung der ungesättigten Carbonsäure 387, [237] die in drei Schritten aus dem Tetralon 386 erhalten wurde (Schema 56 b). [239] [240] lieferte die C9-Diastereomere von 391 als 1.3:1-Gemisch, was ein Hinweis auf die recht hohe Symmetrie von 390 ist.…”