We found that dioxiranes generated in situ from ketones 1-6 and Oxone underwent intramolecular oxidation of unactivated C-H bonds at delta sites of ketones to yield tetrahydropyrans. From the trans/cis ratio of oxidation products 1a and 2a as well as the retention of the configuration at the delta site of ketone 5, we proposed that the oxidation reaction proceeds through a concerted pathway under a spiro transition state. The intramolecular oxidation of ketone 6 showed the preference for a tertiary delta C-H bond over a secondary one. This intramolecular oxidation method can be extended to the oxidation of the tertiary gamma' C-H bond of ketones 9 and 10. For ketone 11 with two delta C-H bonds and one gamma' C-H bond linked respectively by a sp(3) hydrocarbon tether and a sp(2) ester tether, the oxidation took place exclusively at the delta C-H bonds. Finally, by introducing proper tethers, regioselective hydroxylation of steroid ketones 12-14 have been achieved at the C-17, C-16, C-3, and C-5 positions.

H2-etching engineered oxygen vacancies on black TiO2−x to enhance the hot-electron flow and water-gas shift catalytic performance of Au catalysts.

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Background-Peripheral artery disease is a potentially incapacitating disease for which pharmacological options are limited.Stromal cell-derived factor-1 (SDF-1) is a chemokine that attracts endothelial progenitor cells and promotes angiogenesis. Therapeutic use of SDF-1 in hindlimb ischemia may be challenged by proteolytic degradation. We hypothesized that protease-resistant variants of SDF-1 can increase blood flow in an experimental model of hindlimb ischemia. Methods and Results-We screened a peptide library for mutations in SDF-1 that provide resistance to matrix metalloproteinase cleavage. Recombinant SDF-1 proteins carrying the mutations were designed, expressed, and purified, and activity of mutant proteins was tested with receptor activation assays and in vivo Matrigel plug assays. SSDF-1(S4V), which is resistant to both dipeptidylpeptidase IV/CD26 and matrix metalloproteinase-2 cleavage, was active in vitro and induced angiogenesis in vivo. We then designed and purified fusion proteins of SSDF-1 and SSDF-1(S4V) with the sequence of self-assembling peptide nanofibers for incorporation into nanofibers. In a blinded and randomized hindlimb ischemia mouse study, SSDF-1(S4V) delivery by nanofibers improved blood flow as measured by laser Doppler from 23.1Ϯ1.9% (untreated control) to 55.1Ϯ5.7% 6 weeks after surgery (PϽ0.001). Nanofibers alone or SSDF-1 delivered by nanofibers did not improve blood flow. Furthermore, SSDF-1(S4V) delivered by nanofibers increased formation of new arterioles. In vitro, SSDF-1(S4V) attracts smooth muscle cells but does not induce mitosis. Conclusions-SDF-1 engineered to be resistant to dipeptidylpeptidase IV/CD26 and matrix metalloproteinase-2 cleavage and delivered by nanofibers improves blood flow in a model of peripheral artery disease. (Circulation. 2011;123:1306-1315.)

Reported here are three 3D metal-organic framework (MOF) polymorphs with the chemical formula [Fe(2)(H(0.67)bdt)(3)]·xH(2)O (H(2)bdt = 5,5'-(1,4-phenylene)bis(1H-tetrazole)), all of which are constructed from similar Fe(II)-tetrazole rod secondary building units (SBUs) via covalent links, but exhibit diverse spin states regulated by inter-chain cooperativity.

An organocatalytic enantioselective decarboxylative Mannich reaction of malonic acid half oxyesters with cyclic ketimines was developed for the preparation of enantioenriched β‐amino esters with a quaternary stereogenic center and the anti‐HIV drug DPC 083 (see scheme).

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