Two Unusual Methylidenecyclopropane Glucosides from Metaxya rostrata C.Presl

Abstract

Two new natural compounds, (1R,2E)-2-(6-hydroxyhexylidene)cyclopropyl-β-D-glucopyranoside (1) and (6E)-6-[(2R)-2-(β-D-glucopyranosyloxy)cyclopropylidene]hexanoic acid (2), glucosides of a very rare methylidenecyclopropane alcohol, as well as two known glycosides of phenolic acids, namely 4-O-β-D-glucopyranosylcaffeic acid (3) and (E)-4-O-β-D-glucopyranosylcoumaric acid (4), and methyl α-fructofuranoside (5) were isolated for the first time from the rhizomes of the tree fern Metaxya rostrata C.Presl. The structures were elucidated on the basis of detailed spectroscopic data analysis, and the structure of 1 was additionally confirmed by X-ray crystal-structure analysis.

Progress in the Synthesis and Transformations of Alkylidenecyclopropanes and Alkylidenecyclobutanes

“…Figure 6 shows some representative derivatives such as α-amino acids 1028 and 1029, 295 nor-sesquiterpene 1030, 296 unsaturated fatty acid 1031, 297 quinolin-4-one 1032, 298 and glucosides of MCP alcohols 1033 and 1034; these last two were recently isolated from the tree fern Metaxya rostrata C.PRESL (Metaxyaceae). 299 The most studied natural MCP derivatives are the diastereomeric nonproteinogenic amino acids hypoglycin A 1035 and 1036 (Figure 7) that are present in toxic concentration in the unripe fruit of the ackee tree, Blighia sapida Koenig. A recent NMR study proved that also the correlated dipeptide hypoglycin B 1037 exists naturally as a pair of diastereomers.…”

“…Various compounds possessing a methylenecyclopropane moiety have been isolated from natural sources. Figure shows some representative derivatives such as α-amino acids 1028 and 1029 , nor-sesquiterpene 1030 , unsaturated fatty acid 1031 , quinolin-4-one 1032 , and glucosides of MCP alcohols 1033 and 1034 ; these last two were recently isolated from the tree fern Metaxya rostrata C.PRESL (Metaxyaceae) …”

Analysis of the Valgamicin Biosynthetic Pathway Reveals a General Mechanism for Cyclopropanol Formation across Diverse Natural Product Scaffolds

“…Cyclopropanol rings are highly reactive and important functional groups in organic synthesis. , The inherent strain of three-membered cyclopropyl rings (27.5 kcal/mol) enables them to undergo synthetically useful ring opening and ring expansion reactions, , readily forming β-keto radicals upon single-electron oxidation (Figure A). − In addition to serving as useful intermediates for natural product synthesis, cyclopropyl alcohol rings are also directly found, though exceedingly rarely, in natural products themselves. A total of eight cyclopropanol-containing natural products ( 1a , 2 , 3a , 4 – 8 ) have been identified (Figure B). − A cyclopropanol ring can profoundly affect natural product bioactivity . An important example of this is the virulence-associated cyclopropanol-containing polyketide bis-malleicyprol ( 2a ), produced by human and animal pathogens of the Burkholderia pseudomallei complex .…”

Computational insights into strain-increase allylborations for alkylidenecyclopropanes

“…1 ACPs are also presented in a series of biologically active natural products. 2 The common approaches for synthesizing ACPs are based on the addition of cyclopropyl ylides to carbonyl compounds 3 and transition metal-mediated additions of carbenes to allenes. 4 Recently, Aggarwal's group 5 developed an allylboration approach to rapidly access ACPs from vinylcyclopropyl boronic esters.…”