A method for the benzoannulation of ketones

Three-Dimensional Hydrocarbon Cores Based on Multiply Fused Cyclopentane and Indane Units: Centropolyindanes

“…The C 3 v -symmetrical skeleton of the parent tribenzotriquinacene, 42 , can be constructed in different ways. , Unfortunately, these are not very viable but probably more so than the 3-fold benzoannelation of the parent centropolyquinacene, 18 a reaction which has never been reported in the literature whereas syntheses of the singly and doubly benzoannelated triquinacenes have. − However, the first access to the parent tribenzotriquinacene is particularly short (Scheme 10) . In analogy to the synthesis of centrotriindane 41 , 2-benzhydryl-1,3-indandione ( 57 ), , can easily be reduced to the corresponding 1,3-indanediol 58 .…”

Photoisomerization of triquinacene congeners

“…The 1H NMR spectrum (CDCI3) of this stable, oily hydrocarbon shows the expected downfield aromatic singlet ( 7.01,4 H) in addition to multiplets at 3.32 (3 H), 2.32-2.26 (4 H), and 1.70-1.47 (1 H) attributable to (a) the benzylic and apical protons, (b) cyclobutyl hydrogens, and (c) remaining cyclopropyl proton, respectively. In its upfield region, this spectrum is highly reminiscent of that exhibited by 15.9 The paired 13C signals of 14 likewise accord with the Cs symmetry of the molecule. 0a 15…”

“…To elaborate this structure, use was made of the ketone benzoannulation scheme developed earlier in this laboratory. 14 The action of vinylmagnesium chloride converted ketone 98•15 into vinyl alcohol 10 whose dehydration afforded vinyltriquinacene (11). Addition of dimethyl acetylenedicarboxylate to 11 followed by dehydrogenation with DDQ led to adduct 12 which underwent ready saponification and copper-catalyzed decarboxylation to give 13. The triquinacene nature of this hydrocarbon is readily apparent from the rather simple XH NMR spectrum (CDCI3) which consists of two singlets at 7.12 (4 H, aromatic) and 5.67 (4 H, vinylic) in addition to a four-proton multiplet (4.47-3.73) arising from the bridgehead protons.…”

Synthesis of an anthracyclinone bearing an unprecedented aromatic ring-fused bridgehead-hydroxylated bicyclo[3.1.1]heptanol

“…[2][3][4][5][6][7][8] 9 as are their unsaturated derivatives containing double bonds within the six-membered ring. 10 To our knowledge, however, bicyclo[3.1.1]heptanes bearing both a bridgehead-alcohol and a fused aromatic ring (e.g.…”

“…Our proposed route towards β-rhodomycinone 6 involved, (i) acid-catalyzed hydrolysis of the daunosamine sugar from daunomycin.HCl 8a; 11 (ii) conversion of the aglycone (daunomycinone) 9 to its 13-benzenesulfonylhydrazone 10 followed by reduction to give the 13-deoxyanthracyclinone 11; 12 (iii) demethylation of the 4-methoxyl group of 11, 13 and finally (iv) regio-and stereoselective benzylic hydroxylation at C10 with trimethylamine-N-oxide Lack of success with Walsh and Olsen's conditions led us to explore the reduction using other combinations of hydride reagents (NaCNBH 3 , NaBH 4 , NaBH(OAc) 3 15 we noted that (i) 10 was completely consumed within 15 min and that a single new spot of higher R f than 10 was visible by TLC; (ii) the reaction mixtures prominently displayed the previously observed m/z = 365.2 peak in their -ve ion ESMS spectra. After purification by silica gel chromatography and comprehensive 2D-NMR characterization (DQF-COSY, HMQC, HMBC, and NOESY), it was clear that the product was not 11 but the novel anthracyclinone 7.…”