A general synthesis of 1-, 2-, 3-, and 4-substituted benz[a]anthracene-7,12-diones

Abstract

Synthesis of Substituted Benz(a]anthracene-7,12-diones Calcd for C16H1204, parent ion mle 268.073; found 268.071.Preparation of V. Into a pressure bottle was placed 0.09 g (0.43 mmol of III,25 mL of benzene, and a Teflon stirring bar. The solution was cooled to -78 "C and excess I was condensed in. The bottle was capped and the reaction flask was heated to 90 "C and stirred overnight. The flask was then cooled and vented and the solvent was removed under reduced pressure. The crude product was dissolved in 5 mL of hexane and poured into a column of alumina. Elution with hexane removed butadiene polymer. This wm followed by elution with 15% EtOAc/hexane to move the desired product from the column. The eluent was evaporated to yield 0.10 g (90%) of V (greenish crystals), whose spectral (UV, NMR) properties were identical with those of an authentic sample (Aldrich), mp 165-166 "C (lit. mp 166-167 "C).4 2-Methoxy-V was prepared as above by the reaction of 0.10 g (0.42 mmol) of 6-methoxy-111 and excess 9.7 g (200 mmol) of I to yield 0.11 g (91%) of V (yellow crystals), mp 195 "C (lit. mp 200 0C):28 NMR 6 9.2 (d, 1 H, J = 4 Hz), 8.3-8.0 (m, 4 H), 7.8-7.65 (m, 3 H), 7.3 (d, 1 H, J = 4 Hz), 4.0 (s, 3 H); IR, C=O 1670 cm-', C=C 1625; UV 2236 %, (e 1.93 X lo"), 2555 (1.71 X lo"), 2903 (9.5 X lo3), 3010 (8.25 X lo3), 44083-Methoxy-V was prepared as above by the reaction of 0.05 g (0.21 mmol) of 7-methoxy-I11 and excess 9.7 g (200 mmol) of I to yield 0.045 g (75%) of 3-methoxy-V (yellow crystals), mp 145 "C: NMR 6 9.5 (d, 1 H, J = 10 Hz), 8.3-7.9 (m, 4 h), 7.75-7.6 (m, 2 H), 7.

Ambient Synthesis of Tricyclic Naphthalenes via Stepwise Styryl-yne Dearomative Diels–Alder Cyclization

“…Moreover, the key annulation of the sequence is likely a stepwise Diels–Alder reaction, whose energetic profile is surprisingly easier than that of an uncatalyzed concerted process. A similar mechanism is original within the context of dearomative Diels–Alder reactions, which are invariably proposed to be concerted cycloadditions. − According to DFT, stepwise catalytic cyclizations of styryl-ynes are however quite general, and we thus anticipate vast applications of this concept in the future.…”

“…Very similar results were observed by modeling the reaction with 5 MnOOH as a model Mn­(III) derivative ( d ) . The arene-yne cyclization presented here seemed to be a rare event in which the most favorable Diels–Alder mechanism was the stepwise one. − ,, We wondered whether this process might have been a general feature of catalytic dearomative Diels–Alder cyclizations.…”

“…Reactions in which vinylarenes are 4-π partners remain limited, especially for intermolecular approaches . This is due to the intrinsic challenges connected with the energetic toll of a dearomative cyclization.…”

“…This Diels–Alder cyclization should involve a single transition state (TS) according to the literature. − This pathway should have a lower energetic cost compared to that of a stepwise, two-TS manifold (Scheme ). The latter is a feature of a few processes only, which use strongly polarized reagents and involve a zwitterionic or biradical intermediate.…”

Polycyclic aromatic hydrocarbons via 1-(arylmethyl)isobenzo- and -naphtho[2,3-c]furans

“…Caled for C27H1402: C, 87.55; , 3.81. Found: C,87.36;,4]pentapheno [5,6-b,c]furan-6-one (22). This compound was prepared from 0.15 g (0.33 mmol) of 19c in the manner described for 10 except that the reaction was heated for 3 h at 120 °C.…”