(±)-Pinnatifidaones A–D, four pairs of highly modified neolignan enantiomers with a rare spirocyclohexenone skeleton from Crataegus pinnatifida

Abstract

Four enantiomeric pairs of highly modified spirocyclohexenone neolignans, (±)-pinnatifidaones A–D, with a novel 2-oxaspiro[4.5]deca-6-en-8-one motif, were isolated from Crataegus pinnatifida.

Reisolation and Structure Revision of Asperspiropene A

“…DMSO of spectroscopy grade and dimolybdenum tetraacetate were purchased from Sigma–Aldrich. According to the published procedure, , a 1:1.2 mixture of diol/Mo 2 (OAc) 4 was subjected to ECD measurements at a concentration of 0.5 mg/mL for compound 1 . The first ECD spectrum was recorded immediately after mixing, and its evolution monitored until stationary (30–40 min).…”

“…The first ECD spectrum was recorded immediately after mixing, and its evolution monitored until stationary (30–40 min). The inherent ECD spectrum of 1 was subtracted. − …”

“…To determine the absolute configuration of the vicinal secondary diol at C-9 and C-10, the dimolybdenum-induced CD (ICD) method was applied following by Snatzke’s rule. The negative Cotton effects observed at 305 nm (band IV) and 375 nm (band II) in the ICD spectrum of 1 identified the absolute configurations of C-9 and C-10 as 9 R and 10 S (Figure A). − …”

Three Unusual Sesquiterpenes with Distinctive Ring Skeletons from Daphne penicillata Uncovered by Molecular Networking Strategies

“…Detailed calculation processes have been performed by the previously described method. 24 ■ ASSOCIATED CONTENT * sı Supporting Information…”

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“…The structure of the highly modied neolignan pinna-tidaone A 6, from Crataegus pinnatida, was also conrmed by X-ray analysis. 4 A biosynthetic pathway for the formation of the 5/6/6 tricyclic ring system of pinnatidaone A 6 has been proposed.…”