Synthese des Papaverins

Oxidative metabolism of protocatechuic acid by certain soil pseudomonads: a new ring-fission mechanism

“…2,3-Dihydroxybenzoic acid was prepared by the method of Perkin & Robinson (1914), 2,3,4-trihydroxybenzoic acid as described by Kostanecki (1885), and 2,4,5-trihydroxybenzoic acid according to Gattermann & Eggers (1899). Homoprotocatechuic acid (3,4-dihydroxyphenylacetic acid) was prepared by the method of Pictet & Gams (1909). 2,4-Lutidinic acid (pyridine-2,4-dicarboxylic acid) was obtained from L. Light and Co. Ltd.…”

A divergent approach to benzylisoquinoline-type and oxoaporphine alkaloids via regioselective direct ring metalation of alkoxy isoquinolines

“…Deoxygenation of the benzhydrol-type alcohol papaverinol (3b) was found to be less feasible, and needed careful optimization of the reaction conditions. Finally, we found that hydrogenation over Pd/C (10%) in a methanol/sulphuric acid mixture at room temperature for 6 d gives the benzylisoquinoline alkaloid papaverine (9; isolated from Papaver somniferum and other plants; first total synthesis by Pictet and Gams 40 ) in 60% yield. It was also possible to simultaneously remove the O-benzyl protective group and deoxygenate the benzylic position of compound 3d under these conditions to yield the alkaloid palaudine (10; isolated from Papaver somniferum; 41 first total synthesis by O-demethylation of papaverine 42 ) in 75% yield (Scheme 4).…”

Synthesis of the isoquinoline alkaloid, crispine C

“…11 These issues have been overcome by using the Pictet-Gams modification of the BischlerNapieralski reaction. 12 A suitable substrate for this reaction was prepared in three steps from 3,4-dimethoxybenzaldehyde 9 (Scheme 3). Initially, 9 was subjected to a Henry reaction 13 with nitromethane which gave β-nitro alcohol 10 in 85% yield.…”