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Catalytic enantioselective conjugate addition (ECA) reactions with readily accessible and stereochemically defined E‐, Z‐, di‐ and trisubstituted alkenyl aluminum compounds are disclosed. Transformations are promoted by various NHC‐copper catalysts (NHC=N‐heterocyclic carbene), which are derived from enantiomerically pure sulfonate imidazolinium salts. The desired products were obtained in up to 89% yield and >99:1 e.r.; the alkenyl moiety was transferred with complete retention of its stereochemical identity in all instances. The scope and limitations of the approach, key mechanistic attributes, and representative functionalization are presented as well. [ABSTRACT FROM AUTHOR]

Efficient catalytic reactions that can generate C-C bonds enantioselectively, and ones that can produce trisubstituted alkenes diastereoselectively, are central to research in organic chemistry. Transformations that accomplish these two tasks simultaneously are in high demand, particularly if the catalysts, substrates and reagents are inexpensive and if the reaction conditions are mild. Here we report a facile multicomponent catalytic process that begins with a chemoselective, site-selective and diastereoselective copper-boron addition to a monosubstituted allene; the resulting boron-substituted organocopper intermediates then participate in a similarly selective allylic substitution. The products, which contain a stereogenic carbon centre, a monosubstituted alkene and an easily functionalizable Z-trisubstituted alkenylboron group, are obtained in up to 89 per cent yield, with more than 98 per cent branch-selectivity and stereoselectivity and an enantiomeric ratio greater than 99:1. The copper-based catalyst is derived from a robust heterocyclic salt that can be prepared in multigram quantities from inexpensive starting materials and without costly purification procedures. The utility of the approach is demonstrated through enantioselective synthesis of gram quantities of two natural products, namely rottnestol and herboxidiene (also known as GEX1A). [ABSTRACT FROM AUTHOR]

The availability of enantiomerically enriched carbonyl-containing compounds is essential to the synthesis of biologically active molecules. Since catalytic enantioselective conjugate addition (ECA) reactions directly generate the latter valuable class of molecules, the design and development of such protocols represents a compelling objective in modern chemistry. Herein, we disclose the first solution to the problem of ECA of alkenyl groups to acyclic trisubstituted enones, an advance achieved by adopting an easily modifiable and fully catalytic approach. The requisite alkenylaluminum reagents are synthesized with exceptional site- and/or stereoselectivity by a Ni-catalyzed hydroalumination process, and the necessary enones are prepared through a site- and stereoselective zirconocene-catalyzed carboalumination/acylation reaction. The all-catalytic procedure is complete within four hours, furnishing the desired products in up to 77 % overall yield and 99:1 enantiomeric ratio. [ABSTRACT FROM AUTHOR]

The availability of enantiomerically enriched carbonyl-containing compounds is essential to the synthesis of biologically active molecules. Since catalytic enantioselective conjugate addition (ECA) reactions directly generate the latter valuable class of molecules, the design and development of such protocols represents a compelling objective in modern chemistry. Herein, we disclose the first solution to the problem of ECA of alkenyl groups to acyclic trisubstituted enones, an advance achieved by adopting an easily modifiable and fully catalytic approach. The requisite alkenylaluminum reagents are synthesized with exceptional site- and/or stereoselectivity by a Ni-catalyzed hydroalumination process, and the necessary enones are prepared through a site- and stereoselective zirconocene-catalyzed carboalumination/acylation reaction. The all-catalytic procedure is complete within four hours, furnishing the desired products in up to 77 % overall yield and 99:1 enantiomeric ratio. [ABSTRACT FROM AUTHOR]

Catalytic enantioselective allylic substitution (EAS) reactions, which involve the use of alkylor aryl-substituted vinylaluminum reagents and afford 1 ,4-dienes containing a quaternary carbon stereogenic center at their C-3 site, are disclosed. The C-C bond-forming transformations are promoted by 0.5-2.5 mol % of sulfonate bearing chiral bidentate N-heterocyclic carbene (NHC) complexes, furnishing the desired products efficiently (66-97% yield of isolated products) and in high site (>98% SN2')and enantioselectivity [up to 99:1 enantiomer ratio (er)]. To the best of our knowledge, the present report puts forward the first cases of allylic substitution reactions that result in the generation of all-carbon quaternary stereogenic centers through the addition of a vinyl unit. The aryland vinyl-substituted vinylaluminum reagents, which cannot be prepared in high efficiency through direct reaction with diisobutylaluminum hydride, are accessed through a recently introduced Ni-catalyzed reaction of the corresponding terminal alkynes with the same inexpensive metal-hydride agent. Sequential Ni-catalyzed hydrometalations and Cu-catalyzed C-C bond-forming reactions allow for efficient and selective synthesis of a range of enantiomerically enriched EAS products, which cannot be accessed by previously disclosed strategies (due to inefficient vinylmetal synthesis or low reactivity and/or selectivity with Si-substituted derivatives). The utility of the protocols developed is demonstrated through a concise enantioselective synthesis of natural product bakuchiol. [ABSTRACT FROM AUTHOR]

Presents information on the successful construction, cloning and expression of synthetic genes encoding spider silk proteins from Nephila clavipes. Codon selection; Multimerization of DNA sequences; Beta-sheet structure of spider silk multimer proteins.

The article presents information on enantioselective synthesis of alkenyl-substituted quaternary carbons by using nickel (Ni), zirconium (Zr), and copper (Cu) in catalysis.

A correction to the article "A Multicomponent Ni-, Zr-, and Cu-Catalyzed Strategy for Enantioselective Synthesis of Alkenyl-Substituted Quaternary Carbons," is presented.

The article highlights the chemical equations involved in the enantioselective synthesis of alkenyl-substituted quaternary carbons.

Background Hand hygiene is the single-most important nursing home (NH) infection control measure. We piloted a multifaceted hand-washing/surface cleaning intervention in 5 NHs. Our aims were to assess the feasibility of implementing this intervention by assessing staff participation, satisfaction, hand-washing compliance, and whether the intervention was associated with reductions in infection rates, new antimicrobial orders, or overall hospitalization rates. Methods We conducted a randomized, pair-matched pilot intervention in 10 Colorado NHs to reduce infections for all NH residents from October 1, 2015 through May 31, 2016. To evaluate process, we determined online education participation rates, recorded intervention fidelity through weekly reporting measures on microbial surface counts, hand-washing, and infection reporting, and conducted a survey of participating employees. To evaluate potential impacts on clinical outcomes, we collected information on monthly infection log data, new antibiotic orders, and hospitalizations. Results Three of 5 sites had education participation rates >90%, the other 2 were poor (13% and 23%). The majority of participation survey respondents (58%) were promoters of the intervention. Directors of nursing reported hygiene hand-washing data for 19.6/24 (81.8%) weeks and microbial surface count data for 20.4/24 (85.1%) weeks. For the first 4 weeks of the study, the bacterial counts averaged 351.4 ± 497.5 relative light units, the mean value for the last 4 weeks was 127.7 ± 85.1 ( P value = .12). The number of hand-washing occasions per NH resident was steady over time but differed by treatment facility ( P = .03). We observed nonsignificant reductions for total infections (6.7%) and lower respiratory tract infections (19.9%) vs control NHs. There were no significant differences in antimicrobial orders or hospitalization rates pre-post intervention. Conclusions This multifaceted hand-washing and surface cleaning intervention was designed to reduce infection rates among NH residents. In our 10-facility randomized, matched pair pilot study, we observed program compliance and satisfaction along with reductions in surface bacterial counts, but did not observe a statistically significant reduction in infection rates, antimicrobial use, or hospitalizations. [ABSTRACT FROM AUTHOR]

Presents research which created artificial proteins that undergo reversible gelation in response to changes in pH or temperature. Use of recombinant DNA methods; Of what the proteins consist; Formation of coiled-coil aggregates of the terminal domains; Dissociation of the coiled-coil aggregates; Conditions under which gel formation can be controlled.

Abstract: A total synthesis of (−)-6-acetoxy-5-hexadecanolide, in six steps and 37% overall yield from (2R,3S)-1,2-epoxy-4-penten-3-ol is reported. The key synthetic step is a size-selective ring-closing/cross metathesis reaction in which lactone formation and alkyl chain extension are accomplished in an efficient one-pot process. [Copyright &y& Elsevier]