New Tactics in Heterocycles Synthesis

Gold-Catalyzed Cycloisomerization of N-Propargylindole-2-carboxamides: Application toward the Synthesis of Lavendamycin Analogues

“…A limitation to exploiting the biological properties of lavendamycin is its toxicity that may be partly due to the presence of the quinone moiety in the A-ring. Synthetic approaches toward lavendamycin and its structural analogues generally involve either a Bischler−Napieralski cyclodehydration or a Pictet−Spengler cyclization to build the C-ring . The Boger group’s synthesis of 1 was based upon the formation of the B-ring by a Friedlander condensation .…”

Streptonigrin and lavendamycin partial structures. Probes for the minimum, potent pharmacophore of streptonigrin, lavendamycin, and synthetic quinoline-5,8-diones

“…A solution of the bromophenol 28 (30 mg, 0.0804 mmol) in CH2C12 (8 mL) was added dropwise to a solution of potassium nitrosodisulfonate66 (Fremy's salt, 108 mg, 0.402 mmol, 5 equiv) and tetra-n-butylammonium hydrogen sulfate (27.3 mg, 0.0804 mmol, 1 equiv) in 1.0 M phosphate buffer (KH2P04/Na2HP04 = 1,8 mL) at 25 °C. 69 The two-phase reaction mixture was stirred vigorously at 25 °C. After 8 h, additional Fremy's salt (108 mg, 0.402 mmol, 5 equiv) was added to the reaction mixture and it was further stirred at 25 °C (12 h).…”

The total synthesis of streptonigrin and related antitumor antibiotic natural products

“…The basic strategy developed by Kende and co-workers 55,108,109 was to concentrate on the regiocontrolled synthesis of the CD-ring portion and then utilize a Friedländer synthesis for the attachment of the AB-ring system (see Scheme 25a or Scheme 25b). The known ketoenamine intermediate 63, as prepared earlier by Liao,…”