Einfache Synthese von 12-Chloro- und 12-Bromo-5-phenylnaphthacen

Synthesis of the Tetracyclic Core of Anthracycline Antibiotics by an Intramolecular Dehydro Diels−Alder Approach

“…Reaction of 5 in HBr or HCl/ t -BuOH has previously been reported to afford 12-bromo- or 12-chloro-5-phenylnaphthacene; see ref .…”

“…We first prepared diol 5 by reacting commercially available phthaldehyde 4 with 2.1 equiv of lithium phenylacetylide (Scheme ). This provided a quantitative yield of a diastereomeric mixture of diols that coeluted in column chromatography.…”

5-Bromo-12-phenyltetracene

“…The title compound (I) was prepared by a modification of the literature method (Straub & Hambrecht, 1975) by treatment of a DMF solution of 1,2-bis(1-hydroxy-3-phenyl-2-propynyl)benzene with phosphorus tribromide at 273 K. The X-ray structural analysis described here confirmed that the product is 5-bromo-12-phenyltetracene. The molecular parameters of the two molecules in the asymmetric unit, A and B, are essentially the same and for the purpose of this work all bond lengths and angles are quoted as the mean of the respective values.…”

Regioselective Annulation of Unsymmetrical 1,2‐Phenylenebis(diaryl/diheteroarylmethanol): A Facile Synthesis of Anthracene, Tetracene, and Naphtho[b]thiophene Analogues

“…5‐Phenyltetracene (35a): Reduction of crude diketone 33a (0.5 g, 1.49 mmol) with sodium borohydride (0.22 g, 5.95 mmol) followed by workup gave diol 34a . Crude diol 34a (0.4 g, 0.45 mmol) upon annulation with HBr (33 %, 0.21 g, 1.43 mmol) in acetic acid by adopting a procedure similar to that for 14a afforded compound 35a 35 (0.25 g, 71 %) as a pale green solid, m.p. 177–178 °C.…”