575. Syntheses of protoberberine alkaloids

Abstract

The synthesis of O-methylcapauridine, a new synthesis of ( &)-tetrahydropalmatine, and a simplified synthesis of ( f)-ophiocarpine are reported.

Aromatic Cyclodehydration. XLVI.1 Synthesis of Tetrahydropalmatine and Its Analogs2

“…Trialkylaluminum-titanium tetrachloride catalysts are well known for their ability to catalyze the polymerization of olefins, 7 and have been used to polymerize 1-hexyne to linear conjugated structures. 8 Although vinylacetylenes might thus be expected to give complex products with trialkylaluminumtitanium tetrachloride catalysts, we have found that these catalysts promote trimerization of monovinylacetylene and cotrimerization of divinylacety-…”

Viral infection from drinking water

“…Corresponding samples of water were analyzed for microbial indicators of water quality using internationally accepted techniques and principles. 8…”

A Review of the Organic Synthesis and Medicinal Applications of the Natural Product Cytisine

“…The general strategies for the CYT syntheses are presented below based upon final ring closure of the tricyclic structure (A, B or C) in Figure 4. Among the total synthesis of CYT reported are syntheses using pyridine-derived A ring [19,24,27], glutarimide or pyridone-derived A ring [23,25], pyridine derived B-ring [45,46], piperidine derived C-ring [26] and constructions of bispidine core by O'Brien and coworkers [47,48]. The synthetic routes to obtain Ring A were fully developed by O'Brien and coworkers.…”

“…Their research presents a synthesis of (±)-CYT using a ring closing metathesis (RCM) to form ring A (4a) [47]. In syntheses by Bohlmann [49] and Govindachari [46], ring C was built from conveniently substituted quinoline-4-one derivatives (4b). Both of the syntheses employed a trisubstituted starting pyridine to build CYT.…”

“…The trisubstituted pyridine (10a) was formed allowing for conversion into the bis-ester (10b) via reaction of (10a) with Michael acceptor and KOEt in EtOH [46]. This reaction presumably proceeds by methyl group deprotonation, Michael addition and ethoxide elimination to give an intermediate in which the pyridine nitrogen cyclizes onto one of the esters to ultimately form quinolizinone (10b).…”