Studies in the synthesis of camptothecin. An efficient synthesis of 2,3-dihydro-1H-pyrrolo[3,4-b]quinoline

Camptothecin

“…Several N-substituted analogs of CXXI have also been reported (41,42). CXLI Scheme X I X bearing resemblance to camptothecin involved condensation of the 3-pyrrolidinone ethylene ketal CXXXIII with the acid chloride of phthalic acid monomethyl ester CXXXIV to afford the ester amide CXXXV.…”

Synthesis of benzo[3,4‐h][1,6]naphthyridines via Friedländer condensation with active methylenes

“…Among numerous possibilities for ortho joined functionalities those containing carbon and nitrogen are of particular interest, because the numerous combinations of their different oxidation states and easy accessibility of simple derivatives provide them with exceptional versatility in hetero annulation reaction. From literature, it was noted that o‐aminobenzaldehyde, the first and best known member of this class of compounds has been utilized for synthesis of various heterocycles [1–17]. Annulation reaction of heterocyclic aminoaldehydes provide a synthetic entry into heterocyclic systems fused to pyridine [18–21], pyrazole [22–25], and quinoline nucleus [26, 27].…”

2-Aminobenzaldehyde

“…In the base-catalyzed reaction of 2-AB with ethyl 3-oxopyrrolidine-1-carboxylate, two products were formed with the dominant one resulting from the more stable enolate or iminate intermediate (eq 3). 7 The same reaction carried out in acetic acid containing sulfuric acid gives a nearly equal mixture of the two regiochemistries. …”