Synthesis of Stereoisomers of <i>Artemisia</i> and <i>Chrysanthemum</i> Bis(acetylenic) Enol Ether Spiroacetals

An 11-step synthesis is described of two diastereomeric candidates for a bis­(acetylenic) enol ether spiroacetal isolated from <i>Chrysanthemum boreale</i>. Key steps in the synthetic route include spiroacetal lactone alkylidenation and subseqent modified Cadiot–Chodkiewicz cross-coupling to install the bis­(acetylenic) enol ether functionality. From NMR comparisons, neither of the candidates, whose structures were confirmed by single-crystal X-ray diffraction, correspond to the natural product, and a proposal for the correct structure is put forward

Synthesis of Pandamarilactone‑1

The first total synthesis of pan­damari­lactone-1, an alkaloid of <i>Pandanus amaryllifolius</i>, is reported. The nine-step synthesis features furan oxidation with singlet oxygen and then spiro-<i>N,O</i>-acetalization and elimination to generate the natural product and further <i>Pandanus</i> alkaloids, pan­damari­lacto­nines A–D

Synthesis of Imidazolidin-4-ones via a Cytochrome P450-Catalyzed Intramolecular C–H Amination

Expanding Nature’s catalytic repertoire to include reactions important in synthetic chemistry opens new opportunities for biocatalysis. An intramolecular C–H amination route to imidazolidin-4-ones via α-functionalization of 2-aminoacetamides catalyzed by evolved variants of cytochrome P450_BM3 (CYP102A1) from Bacillus megaterium has been developed. Screening of a library of ca. 100 variants based on four template mutants with enhanced activity for the oxidation of unnatural substrates and preparative scale reactions in vitro and in vivo show that the enzymes give up to 98% isolated yield of cyclization products for diverse substrates. 2-Aminoacetamides with one- and two-ring cyclic amines bearing substituents and aliphatic, alicyclic, and substituted aromatic amides are cyclized. Regiodivergent C–H amination was achieved at benzylic and nonbenzylic positions in a tetrahydroisoquinolinyl substrate by the use of different mutants. This C–H amination reaction offers a scalable route to imidazolidin-4-ones with varied functionalized substituents that may have desirable biological activity

Philornis Intensity and Genetic Population Floreana Tree Finches_Am Nat

Total Philornis downsi larvae intensity per nest for tree finches breeding on Floreana Island in 2005, 2010 and 2012. Genetic population refers to population assignment based on analyses of microsatellite loci (using the program STRUCTURE). Male colour and putative species assignment are also provided (STF=small tree finch, MTF=medium tree finch, LTF= large tree finch)

Genetic Population and Morphology_Floreana Tree Finches 2005 and 2010_Am Nat

Morphological measurements of tree finches sampled on Floreana Island, Galapagos, 2005 and 2010. Techniques for measuring morphological features are described in the associated manuscript. Genetic population refers to population assignment based on analyses of microsatellite loci (using the program STRUCTURE)

Two Total Syntheses of Trigoxyphins K and L

Two total syntheses are presented for trigoxyphins K and L, tricyclic terpenoids from Trigonostemon xyphophylloides. The first proceeds via electrophlic cyclization in A/C-ring substrates to close the B ring at C4–C5 and then 1O2-mediated hydroxybutenolide formation to trigoxyphin L, with Luche reduction leading to trigoxyphin K. The second route develops from tetralone ring expansion to a B/C-ring intermediate that, by one-step O-demethylation–lactonization–isomerization, affords trigoxyphin K and then trigoxyphin L following enolate oxygenation