Isopropylation of 6-Methoxy-1-tetralone

doi:10.1080/00304948.2019.1651173

Paper

Isopropylation of 6-Methoxy-1-tetralone

Published Aug 16, 2019 · A. K. Banerjee, Liadis Bedoya, Jossblerys DaSilva

Organic Preparations and Procedures International

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Abstract

We recently reported the successful introduction of the isopropyl group into the aromatic ring of 5-methoxy-1-tetralone and 7-methoxy-1-tetralone using 2-propanol (2PrOH) and polyphosphoric acid (PPA). These results have now prompted us to carry out the isopropylation of 6-methoxy-1-tetralone (1) as a possible route to 5-isopropyl-6methoxy-1-tetralone (3) and 7-isopropyl-6-methoxy (4) respectively (Scheme 1). The tetralone 3 and tetralone 4 are potential intermediates for the preparation of the bioactive phenolic diterpenes Totarol 5 and Sempervirol 6 respectively (Scheme 1). These compounds were originally isolated from the wood of Tetraclinis articulata and from the resin of Cupressus sempervirens respectively. Recently Totarol 5 has also been discovered in the Chilean Podocarpaceae, juniperus and Mediterranean propolis. It has been approved for use as an antimicrobial additive in toothpaste and acne treatments and for prophylaxis of schistosomiasis and fascioliasis in humans, sheep, goats and cattle. The antibacterial activity of Totarol 5 and anthelmintic activity of Sempervirol 6 are well documented. In the event, to a mixture of commercially available PPA and 2-PrOH heated to 75–80 C we added the tetralone 1 and the mixture was heated for 5 h to obtain a viscous material. This contained a mixture of recovered tetralone 1 and three products of different intensities (but distinct Rf values) as evidenced in thin layer chromatography. Chromatographic purification afforded tetralones 2, 3 and 4 in yields of 10%, 20% and 32% respectively (Scheme 1). The structures of the tetralones 2, 3 and 4 were ascertained by H NMR and C NMR spectroscopy (see Experimental Section). When the isopropylation experiment was carried out by heating the reaction mixture at 100–110 C for 10h, the tetralone 4

Study Snapshot

Isopropylation of 6-methoxy-1-tetralone can produce 5-isopropyl-6methoxy-1-tetralone (3) and 7-isopropyl-6-methoxy (4), which are potential intermediates for the preparation of bioactive phenolic diterpene

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

Isopropylation of 6-Methoxy-1-tetralone

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