Molecular Reconstruction with Stereochemical Relay: An Investigation into the Rearrangement of Spiro[4.5]decadienone to Benzoxepane.

Herein, we report the unusual skeletal rearrangement of spiro[4.5]decadienone to benzoxepane. In particular, Lewis acid-promoted epoxide-opening ipso-cyclization of aryl epoxides afforded spiro[4.5]decadienone intermediates. Subsequent thermal activation assembled a benzoxepane core via rearomative molecular reorganization. The sequence was high-yielding and highly diastereoselective but sensitive to the aromatic substitution pattern and the epoxide side chain. Mechanistic studies suggested that the rearrangement proceeded via an uncommon intramolecular enolate attack onto the electrophilic O of p-quinone oxonium zwitterion. DFT calculations helped rationalize the product distribution and the origin of diastereoselectivity. Initial investigation into the application of this chemical transformation is also presented.

Total Synthesis of Pentaketide Ansamycin Microansamycin H.

Herein, we report the first total synthesis of pentaketide ansamycin microansamycin H. Key to our success was the endo-selective epoxide-opening O-alkylation to construct the elusive seven-membered benzoxepane core. Due to the electron-rich disposition of the aromatic substrate, our pivotal transformation was hindered by competing electrophilic aromatic substitution at multiple C-based nucleophilic sites that generated kinetically favored products. Judicious choices of transition metal Lewis acid promoters biased toward the formation of the desired oxepane.

Synthesis and Anticancer Activity of Pentafluorobenzenesulfonamide Derivatives as Caspase-Dependent Apoptosis-Inducing Agents.

Arylsulfonamides are ubiquitous in a number of anticancer agents, and fluorine substitution on aromatic rings often improves drug profile. Herein, a series of novel pentafluorobenzenesulfonamide derivatives with different molecular scaffolds were readily synthesized and assessed for their antitumor activities against multiple cancer cell lines, including A549, HepG2, HuCCA-1, and MOLT-3. Dihydroimidazoline-containing analogue and its Diels-Alder cycloadducts exhibited enhanced cytotoxicity at micromolar range while the incorporation of other heterocyclic cores via nucleophilic substitution reaction resulted in diminished potency. Selected analogues were shown to induce the accumulation of cleaved forms of Casp-9, Casp-7 and PARP in cancer cells, indicating intrinsic apoptosis via a caspase-dependent process.

Genome Sequence of Streptomyces cavourensis BUU135, Isolated from Soil from a Tropical Fruit Farm in Thailand.

Streptomyces cavourensis BUU135 is a bacterial species isolated from the soil of a tropical fruit farm. The genome of S. cavourensis BUU135 comprises a gene encoding nebramycin 5' synthase, which produces nebramycin 5' by catalyzing the O-carbamoylation reaction of tobramycin. The newly sequenced 7.66-Mb draft genome of S. cavourensis BUU135 may contribute to the discovery of novel natural products derived from this organism.

First Draft Genome Sequence of Thermophilic Laceyella tengchongensis BKK01, Isolated from Municipal Solid Waste in Thailand.

Laceyella tengchongensis BKK01 is a thermophilic bacterium isolated from municipal solid waste. The genome of L. tengchongensis BKK01 includes a gene putatively encoding gramicidin S synthase. Gramicidin S has antibiotic activity against some bacteria and fungi. The newly sequenced 3.44-Mb draft genome of L. tengchongensis BKK01 will shed some light on the biosynthesis of gramicidin S.

Synthesis and antitumor activity of bis(arylsulfonyl)dihydroimidazolinone derivatives.

A series of novel bis(arylsulfonyl)dihydroimidazolinones with different aryl substitution patterns were readily synthesized and evaluated for their antitumor activities. Some of the newly synthesized compounds exhibited cytotoxicity at micromolar range against multiple cancer cell lines, including A549, HepG2, HuCCA-1, and MOLT-3. The most potent analogue contained pentafluorobenzenesulfonyl groups, which could be chemically elaborated to serve as a potential pharmacophore.

Draft Genome Sequence of Haloferax volcanii SS0101, Isolated from Salt Farms in Samut Sakhon, Thailand.

Haloferax volcanii SS0101 is a halophilic archaeon isolated from salt farms in Thailand. The genome sequence of H. volcanii SS0101 contains a gene encoding capreomycidine synthase, a key enzyme for capreomycidine biosynthesis. This 3.8-Mb draft genome sequence of H. volcanii SS0101 will provide the tools for investigating genes involved in capeomycidine production in haloarchaea.

Draft Genome Sequence of Multidrug-Resistant Proteus mirabilis CKTH01, Isolated from Raw Chicken Meat.

Proteus mirabilis CKTH01 is a pathogenic bacterium isolated from raw chicken meat. The genome sequence of P. mirabilis CKTH01 contains genes encoding multidrug efflux pumps, which are the virulence factors of the antibiotic-resistant bacterium. This 3.98-Mb draft genome sequence of P. mirabilis CKTH01 will contribute to the understanding of the distribution of multidrug-resistant P. mirabilis in raw chicken meat at the open markets.

Total Synthesis of the Marine Ladder Polyether Gymnocin B.

Herein, we report the first total synthesis of marine ladder polyether gymnocin B (1) based on a two-phase strategy. In Phase I, inspired by the proposed biosynthesis, epoxide-opening cascades assemble 10 out of 15 cyclic ether rings making up the molecular core. In the subsequent Phase II, coalescence elevates the molecular complexity further by coupling of these subunits. Our two-phase synthetic approach significantly improved the step efficiency of the synthesis of this class of natural products.

Draft Genome Sequence of Thermophilic Halotolerant Aeribacillus pallidus TD1, Isolated from Tao Dam Hot Spring, Thailand.

Aeribacillus pallidus TD1 is a thermophilic bacterium isolated from a hot spring in Thailand. The genome sequence of A. pallidus TD1 contains a gene-encoded naphthalene dioxygenase, which is a key enzyme for naphthalene degradation. This 3.7-Mb draft genome sequence of A. pallidus TD1 will contribute to the understanding of polycyclic aromatic hydrocarbon (PAH) degradation in high-temperature environments.

Draft Genome Sequence of Bacillus salarius IM0101, Isolated from Hypersaline Soil in Inner Mongolia, China.

Bacillus salarius IM0101 is a halophilic bacterium that was isolated from soil in Inner Mongolia, China. The genome sequence of B. salarius IM0101 contains a biomarker gene for polyhydroxyalkanoate (PHA) synthesis. This 6.9-Mb draft genome sequence of B. salarius IM0101 will provide new insights into the organism's PHA production machinery.