Prenylated Acetophloroglucinol Dimers from Acronychia trifoliolata: Structure Elucidation and Total Synthesis

Abstract

The isolation of 12 secondary metabolites, including seven new acetophenone monomers, from the 50% CH 3 OH/CH 2 Cl 2 extract (N089419-L/6) of Acronychia trifoliolata was reported previously. In the present work, three new prenylated acetophenone dimers (1-3) and five known dimers (4-8) were isolated, and their structures were elucidated by using various NMR spectroscopic techniques and HRMS. Among the new dimers, an unprecedented 4-isobutyl-3 isopropyltetrahydro-2H-pyran ring was observed in the structure of 1. This study is the first to report the formation of a 2H-pyran ring between two prenylated acetophloroglucinols. Only four related dimers have been reported before, and they were formylated phloroglucinol dimers from the family Eucalypteae. Compounds 2 and 3 are acrovestone-like dimers, and the structure of 3 was confirmed by total synthesis. The evaluation of the antiproliferative activity of isolated and synthesized acrovestone-like dimers indicated that a double bond in the prenyl-like moiety as *

New Acetophenones and Chromenes from the Leaves of Melicope barbigera A. Gray

“…Moreover, enhanced research is needed to conserve the species and to obtain new sources for further natural product discovery. Acetophenones and chromenes have been discovered in 14 species of Melicope [11,[14][15][16][17]27,[51][52][53][54][55][56][57][58] as well as in some species of its close relatives Acronychia and Medicosma [33,46,[59][60][61][62][63][64]. Due to the great variability of the acetophenones and chromenes in these genera, they may be of interest as biomarkers for chemotaxonomy.…”

Recent advances in the synthesis of natural products containing the phloroglucinol motif

“…In 2019, Nakagawa-Goto rstly isolated and identied a new prenylated acetophenone dimer, acrofolional (81, Scheme 13) from Acronychia trifoliolata. 65 A clear 13 C-NMR spectrum of the compound could not be obtained due to limited quantity, thus the team decided to conrm its structure via total synthesis. Monoprenylated acylphloroglucinol 78 was obtained from acetophloroglucinol (53) based on the previous approach by the same team.…”

Acrotrione B, a Prenylated and Highly Oxidized Xanthenoid with Antibacterial and Anti-proliferative Activities from the Roots of Acronychia pedunculata

“…Extracts of its roots, stems, leaves, and fruit have been used as a treatment for diarrhea, cough, asthma, sores, ulcers, itchy skin, pain, rheumatism, and fever [6]. Previous phytochemical investigations of this plant report mostly isoprenylated acetophenones and their dimers, quinoline alkaloids, terpenoids, and coumarins as its secondary metabolites [7][8][9][10][11][12][13][14][15].…”