High‐field NMR studies on neo‐clerodane diterpenoids from Mexican Salvia species

Abstract

High-field 2D NMR studies were performed on nine neoclerodane diterpenoids. Unambiguous assignments of the I3C signals and proton chemical shifts were achieved which led to the revision of some previous assignments.KEY WORDS neo-clerodane diterpenoids 2D NMR

Reaction of the Molluscicide Glaucolide B with Bentonite

“…Therefore, the hydroxy group should be attached to C-5 with a ßorientation in accordance with the observed coupling constant (/5-6 = 9 Hz), indicative of a trans relationship between these protons. This conclusion is supported by the resistance of compound 3 toward dehydration and also by -, 13C-, DEPT, HETCOR, and HMBC (12) nmr experiments, summarized in Tables 1 and 2, which established that the remain-der of the molecule stays unchanged. Therefore, structure 3 was proposed.…”

“…[1] CR¡ 0.4; 40 mg) and compound 2 (RfQ.5', 12 mg) were isolated. Both compounds displayed spectroscopic data in accordance with those previously reported (10,11).…”

“…Upon acetylation, compound 4 gave the acetyl derivative 5 whose 1Hnmr spectrum showed signals for three acetate methyl groups, one vinylic methyl group ( 1.53), and the H-5 signal shifted to lower field. bXHCORR, HMQC, CHORTLE (PROTON) (12).…”

Diterpenoids

“…The crystal structure of abietic acid has been rep~rted.~' Some dehydroabietic acid derivatives including (53) have been is~lated'~ from Nepeta teydea (Labiatae). Examination of the leaves of Juniperus chinensis (Cupressaceae) aff~rded'~ (54) whilst 3~-hydroxy-l-oxototarol (55) was obtained'* from the roots.…”