Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

Synthesis of C-Ring-Substituted Vasicinones and Luotonins via Regioselective Aza-Nazarov Cyclization of Quinazolinonyl Enones

“…In comparison to other rings, reports on modifications of the C-ring have been rather limited (i.e., C-ring methoxycarbonyl and acetylamino). To address this, we set out (i) to develop facile access to C-ring-substituted luotonin A analogues to identify a potential lead for further optimization, and (ii) to extend the resulting methodology to structurally related alkaloids, such as 22-hydroxyacuminatine ( 6 ), rutaecarpine ( 4 ), rosettacin, and evodiamine (see Figure ).…”

“…8,9 The synthetic modifications reported thus far on the luotonin A core include principally alkyl and haloalkyl substituents on the A-ring; 10,11 aryl, 9f alkyl, 12 aminoalkyl, 12 and trifluoromethyl substituents on the Bring; 13 and halo, trifluoromethyl, and phenyl substituents on the E-ring. 14 In comparison to other rings, reports on modifications of the C-ring have been rather limited (i.e., C-ring methoxycarbonyl 15 and acetylamino 16 ). To address this, we set out (i) to develop facile access to C-ring-substituted luotonin A analogues to identify a potential lead for further optimization, and (ii) to extend the resulting methodology to structurally related alkaloids, such as 22-hydroxyacuminatine (6), 17 rutaecarpine (4), 18 rosettacin, 19 and evodiamine 20 (see Figure 1).…”

Xylochemical Synthesis of Cytotoxic 2-Aminophenoxazinone-Type Natural Products Through Oxidative Cross Coupling

“…be obtained from black liquor through anodic oxidation and a selective extraction, − in a simple and high yielding sequence (Scheme ). − Due to its propensity to undergo aerial oxidation, the homodimerization product peristrophine ( 3 ) is rapidly formed and isolation of the free aminophenol 1 itself is not possible unless oxygen is being rigorously excluded.…”

Efficient synthesis of ether phosphonates using trichloroacetimidate and acetate coupling methods

“…3,4-Dimethoxybenzaldehyde 1c and 3-methoxy-4-(prop-2-ynyloxy)benzaldehyde 1d was prepared by alkylation of vaniline as described in the literature. 24 Diethyl hydroxy(substitutedphenyl)methyl phosphonate 2a-d 25 To a mixture of (20.7 g, 0.15 mol) of diethyl phosphonate and 1.09 g (0.011 mol) of triethylamine was added (0.15 mol) of aldehydes 1a-d portion wise during a period of 1 h at 50-70 C.…”

“…3,4-Dimethoxybenzaldehyde 1c and 3-methoxy-4-(prop-2-ynyloxy)benzaldehyde 1d was prepared by alkylation of vaniline as described in the literature. 24 …”