Novel syntheses of camptothecin alkaloids, part I. Intramolecular [4+2] cycloadditions of N-arylimidates and 4H-3,1-benzoxazin-4-ones as 2-aza-1,3-dienes

Review Camptothecin: Current Perspectives

“…They used an efficient intramolecular DielsAlder reaction (Fig. 3, C), which is now successful in an industrial scale [17]. In succession, Blagg and Boger described a new synthesis of 20(S)-CPT based on a DielsAlder cycloaddition of the electron deficient diene Nsulfonyl-1-aza-1,3-butadiene with the electron rich dienophile for the assembly of precursor to CPT (Fig.…”

“…This is the representative shortest total asymmetric synthesis through joining of the A/B-ring and the D/E-ring through construction of the C-ring, which advanced the industrial production of CPT [23] Anderson et al have described a novel expeditious synthesis of racemic 20(S)-CPT (Scheme 2) [24]. The synthesis began with etherification of hydroxy pyridone (16b), which provides from dizao imide (14)based on siomünchnone cycloadditions according to Padwa at two steps [25,26], with (Z)-methyl4-chloro-2-methoxybut-2-enoate and cesium carbonate to give derivative (17), in preparation for a Claisen rearrangement to introduce a substituent in the β position and afford the hydroxy pyridone (18a). Compound (18b) could be provided by hydrogenation and then converted into 19a.…”

Efficient Total Synthesis of (S)‐14‐Azacamptothecin

“…Sharpless asymmetric dihydroxylation (Sharpless AD) of the cyclic enol ether 6 and subsequent iodine‐mediated oxidation of the resulting hemiacetal intermediate were employed to establish the lactone moiety and its C‐20 stereochemistry. Our recently developed aza Diels–Alder approach14 via the Fortunak intermediate15 was considered to construct both the B and C rings of key cyclic enol ether 6 from the simple amide 7 in a one‐pot fashion.…”

A facile synthesis and antibacterial activity of novel pyrrolo[3,4-b]quinolin-2(3H)-yl)benzamides

“…On the other hand, it has been well established that the synthetic compounds with quinoline and pyrrol scaffold in their moieties exhibit a wide range of biological activities such as psychotropic (11), antiallergic (12), anti-inflammatory (13) and estrogenic activity (14). Pyrrolo [3,4-b]quinoline-based molecules are an important hybrids of these compounds ( Figure 1), and can be found as naturally occurring compounds such as camptothecin (15), mappicine (16) and quinocitrinines A and B (17). These compounds are associated with a wide variety of pharmacological properties including antiviral (15,16), cytotoxic (18), antimicrobial (19), anticonvulsant (20) and antitumor activities (21)(22)(23).…”