Michael‐Addition von 3‐Oxoglutarsäureestern an 7‐Oxo‐7H‐benzocyclohepten‐6,8‐dicarbonsäureester: Synthese von benzanellierten Oxa‐homoadamantanen

Abstract

Die 7‐Oxo‐7H‐benzocyclohepten‐6,8‐dicarbonsäureester (4,5‐Benzotropon‐2,7‐dicarbonsäureester) 3 reagieren mit den 3‐Oxoglutarsäureestern 2 unter doppelter Michael‐Addition zu den vollständig enolisierten 7,10‐Dihydroxy‐8,9‐dihydro‐9,5‐propeno‐5H‐benzocyclohepten‐6,8,10,12‐tetracarbonsäureestern 6, die auch aus o‐Phthaldialdehyd (1) und zwei mol 3‐Oxoglutarsäureester zugänglich sind. Die Ester 6 lassen sich zum 5,6,8,9‐Tetrahydro‐5,9‐propano‐7H‐benzocyclohepten‐7,11‐dion (8) verseifen und decarboxylieren. Das Diketon 8 reagiert mit einigen nucleophilen Reaktionspartnern (Wasser, Lithiumalanat, Natriumboranat, Methyl‐magnesiumjodid, Nitromethan/Natriummethanolat) und mit Phosphorpentachlorid unter transannularem Ringschluß zu den 6,7,8,9‐Tetrahydro‐7,11‐epoxy‐5,9‐propano‐5H‐benzocycloheptenen (“Oxa‐benzohomoadamantenen”) 12a–e. Auch der Grundkörper 12f läßt sich herstellen. Die Wolff‐Kishner‐Reduktion von 8 verläuft ebenfalls ungewöhnlich: Transannulare C‐C‐Verknüpfung führt zum 5,7,9‐Propan‐1,2,3‐triyl‐6,7,8,9‐tetrahydro‐5H‐benzocyclohepten‐7‐ol (16).

New oxapolycyclic cage amines with NMDA receptor antagonist and trypanocidal activities

“…16 Reaction of alcohol 5 with several primary amines led to the recovery of the starting material. However, reaction of 5 with aqueous hydrazine led to the known hydrazine 6 in 79% yield, probably due to the a-effect ensuring a higher nucleophilicity of hydrazine.…”

Proximate, “Parallel‐In‐Plane” Preoriented Bis(diazenes) − In‐Plane Delocalized Bis(homoconjugated) 4N/5(6)e Anions

“…Thus, the green radical anions (λ max ϭ 700Ϫ900 nm) generated through short contact of the A-(A 12, A 22 ), C-(34a, 34c), and D-type (46) , and 2Li ϩ 34c 2Ϫ dianions (λ max ϭ 360Ϫ430 nm), the absorbance remaining constant for weeks. Thermodynamically meaningful information became available when the first and second reduction potentials (E 1/2 ca.…”

“…UV (CH 3 CN): λ max (ε) ϭ 297 nm (sh, 190), 225 (2000). 1 [3.3.1]nonane-2,6-dione [46] (19.2 g, 126.0 mmol), ethane-1,2-diol (17 mL, 332 mmol), and p-toluenesulfonic acid ϫ H 2 O (0.3 g) in benzene (150 mL) was heated at reflux for 24 h with azeotropic removal of water. After standard workup (diethyl ether) and sublimation of the solid residue, colorless needles (22.6 g, 75%) were isolated; m.p.…”

“…Recourse was therefore made to the 9,10-benzoanellated derivative 46, for which the calculated d/ω parameters (MMX) hardly differed from those of parent D and for which the starting material was readily accessible in the form of benzocyclooctene-3,7-dione 39. [46] However, the seemingly trivial transformation 39 Ǟ 41 proved tricky. Ultimately, the Fetizon procedure [47] was once more [48] found to be of practical use, superior to various procedures that had been severely hampered by side reactions (primarily bridging in the eight-membered ring [49] ).…”

Bridged aromatic alkenes for the study of carbocation–π interaction

“…containing functionality suitable for introduction of the bridgehead propenyl group, two 9,15 were pursued experimentally (Scheme 1). Initially, Lawton's concise approach 9 to ketoester 14 by reaction of the pyrrolidine enamine of 2-indanone 17 with methyl b, b 0 -dibromoisobutyrate 18 was explored.…”