Versatile Synthesis of Dihydroquinolines and Quinoline Quinones Using Cyclobutenediones. Construction of the Pyridoacridine Ring System

1-BOC-2-lithio-1,4-dihydropyridines were condensed with 3,4-disubstituted cyclobutenediones to produce 1,2-adducts. Neat thermolysis under oxygen-free conditions produced substituted 1,4-dihydroquinoline hydroquinones in which the tert-butoxy residue of the BOC group was displaced by a phenolic residue, generating an oxazolone ring that functioned to protect both rings of the dihydroquinoline hydroquinone from untimely oxidation. Oxidative aromatization with concomitant loss of the oxazolone ring was achieved using 2 equiv of o-chloranil in acetic acid and provided substituted quinoline quinones in good yields. By use of this strategy, a concise synthesis of the pyridoacridine ring system was achieved

(η³-Pyranyl)TpMo(CO)₂ Complexes as Chiral Scaffolds for the Enantiocontrolled Construction of 2,3,6-Trisubstituted Dihydropyrans (Tp = Trispyrazolylborate)

(η3-Pyranyl)TpMo(CO)2 Complexes as Chiral Scaffolds for the Enantiocontrolled Construction of 2,3,6-Trisubstituted Dihydropyrans (Tp = Trispyrazolylborate

Reactions of (<i>tert</i>-Butyldimethylsilyl)alkynes with IPy₂BF₄: Selective Synthesis of Novel Head-to-Head Dimers

Reactions of (tert-Butyldimethylsilyl)alkynes with IPy2BF4:  Selective Synthesis of Novel Head-to-Head Dimer

Reactions of (<i>tert</i>-Butyldimethylsilyl)alkynes with IPy₂BF₄: Selective Synthesis of Novel Head-to-Head Dimers

Reactions of (tert-Butyldimethylsilyl)alkynes with IPy2BF4:  Selective Synthesis of Novel Head-to-Head Dimer