Polyhydroxyalkanoates (PHAs) have attracted increasing interest as sustainable plastics because of their biorenewability and biodegradability in the ambient environment. However, current semicrystalline PHAs face three long-standing challenges to broad commercial implementation application: lack melt processability, mechanical brittleness, unrealized recyclability, last which is essential for achieving a circular economy. Here we report synthetic PHA platform that addresses origin thermal...

Commercial adhesives are petroleum-based thermoset networks or nonbiodegradable thermoplastic hot melts, making them ideal targets for replacement by biodegradable alternatives. Poly(3-hydroxybutyrate) (P3HB) is a biorenewable and alternative to conventional plastics, but microbial P3HB, which has stereoperfect stereomicrostructure, exhibits no adhesion. In this study, elucidating the fundamental relationship between chemocatalytically engineered P3HB stereomicrostructures adhesion...

Tetracyclic indolines are ubiquitous skeletons in bioactive natural products and pharmaceuticals, efficient methods for their enantioselective synthesis highly desired. Here, we report an three-component formal [2 + 2 2] cycloaddition reaction between indoles, 2,3-dihydropyran, methylene malonates rapid construction of optically active tetracyclic bearing four continuous stereocenters. Although the optimal catalyst Cu(II)/BOX displays only moderate enantioselectivities either cyclobutanation...

A first highly enantioselective catalytic method has been developed for the reduction of aromatic N-alkyl ketimines by trichlorosilane under mild conditions using newly designed Lewis base organocatalyst 3 that incorporates C- and S-chirality (see scheme). Excellent enantioselectivities up to 99.6 % ee high yields were obtained a wide range substrates. Supporting information this article is available on WWW http://www.wiley-vch.de/contents/jc_2111/2008/z801479_s.pdf or from author. Please...

First, test the water! In presence of a chiral Lewis base catalyst 2, supposedly moisture-unfriendly reduction system with trichlorosilane was found to be highly efficient and enantioselective when using water as an additive. For first time, this method enables broad range N-alkyl β-enamino esters 1 give β-amino 3 in good high yields excellent enantioselectivities (see scheme).

Abstract Six multicomponent reactions were developed by using aldo‐X reagents and α‐oxoketene dithioacetals with indoles or amines as substrates, which can be used to prepare many heterocycles, such dihydrocoumarins, quinolines, furans pyrroles, in a straightforward way. A combination of two bifunctional is the key make discovery these possible because have minimum reactive sites, enable different substrates assembled together various manners.

The crystal structures of isotactic and atactic poly(3-hydroxy-2,2-dimethylbutyrate) (P3H(Me)2B) are presented. Samples P3H(Me)2B (at-(R/S)-P3H(Me)2B) the R S enantiomers (it-(R)-P3H(Me)2B it-(S)-P3H(Me)2B, respectively) have been synthesized by ring opening polymerization racemic chiral dimethyl-butyrolactones employing a superbase catalyst. A 1:1 mixture two (it-(R,S)-P3H(Me)2B) has also prepared. Both pure enantiomer polymers crystallize showing identical diffraction patterns, indicating...

Inspired by the highly efficient and enantioselective reactions catalyzed biomacromolecules, developing artificial helical polymer-supported catalysts is an attractive meaningful field. In this work, a series of polymers...

The electrocatalytic nitrate reduction reaction (NitRR) is a promising alternative to the traditional Haber-Bosch process. However, competitive hydrogen evolution results in poor NH3 selectivity (S NH3). Here, Cu-Co bimetallic catalyst supported on biomass-derived porous carbon (Cu-Co/BPC) designed and synthesized. Interestingly, presents high yield rate of 9114.1 ± 244.8 μg h-1 cm-2 at -1.4 V (vs. RHE) faradaic efficiency (FE) 84.5 1.6% -1.0 RHE). Notably, S Cu-Co/BPC kept above 94.2% under...

We have successfully synthesized a Ni–Co bimetallic phosphide catalyst for the electrocatalytic reduction of nitrate to produce ammonia.

L-Pipecolinic acid derived Lewis basic N-formamide 5e has been developed as a first highly effective catalyst for the asymmetric reduction of aromatic and aliphatic ketones well ketimines in good to high enantioselectivity.

Abstract Catalytic asymmetric reduction of N‐unsubstituted β‐enamino esters represents a major challenge for catalysis. In this paper, the first organocatalytic system that could be used hydrosilylation has been developed. Using N ‐ tert ‐butylsulfinyl‐ L ‐proline‐derived amides and ‐pipecolinic acid‐derived formamides as catalyst, broad range β‐aryl‐ β‐alkyl‐substituted free β‐amino prepared with high yields enantioselectivities. The practicality was illustrated by gram‐scale synthesis...

A highly enantioselective synthesis of various chiral heterobicyclic molecules including spiroaminals and fused bicyclic acetals has been developed via a copper catalyzed cyclopropanation-rearrangement (CP-RA) approach under mild reaction conditions. Remarkably, the asymmetric CP-RA for exocyclic vinyl substrates without pro-stereogenic carbon at β-position realized first time broad substrate scope with excellent results (33 examples; 34-99 % yields; >95/5 dr 91-99 ee) achieved. An...

A library of well-defined aminopyridine iron(II) precatalysts with a tertiary amine moiety have been prepared and serve as highly efficient for polymerization isoprene other biobased conjugated dienes, delivering the corresponding polyolefin elastomers. These iron complexes were synthesized further verified by ATR-IR, NMR, HR-MS spectroscopy, elemental analysis. In addition, single-crystal diffraction analysis reveals that structures representative Fe-Me, Fe-Et, Fe-iPr all displayed...

Within the large poly(3-hydroxyalkanoate) (PHA) family, C3 propionates are much less studied than C4 butyrates, with exception of α,α-disubstituted propionate PHAs, particularly poly(3-hydroxy-2,2-dimethylpropionate), P3H(Me)2P, due to its high melting temperature (Tm ∼ 230 °C) and crystallinity (∼76%). However, inefficient synthetic routes monomer 2,2-dimethylpropiolactone [(Me)2PL] extreme brittleness P3H(Me)2P largely hinder broad applications. Here, we introduce simple, efficient...

Abstract The organocatalytic trichlorosilane reduction system has been successfully utilized to develop a multi‐step tandem approach for the easy preparation of chiral 2‐methyl‐3‐alkylindolines starting from simple 2‐methylindoles and aldehydes. A broad range 2‐methyl‐3‐alkylindoline products was obtained with high yields enantioselectivities excellent stereoselectivities by this approach. magnified image

L-Valine derived N-sulfinamides have been developed as efficient enantioselective Lewis basic organocatalysts for the asymmetric reduction of N-aryl and N-alkyl ketimines with trichlorosilane. Catalyst 3c afforded up to 99% yield 96% ee in 98% ketimines.

Copper catalyzed enantioselective [4 + 2] annulations of D‐A cyclobutanes and aldehydes have been developed. In the presence a side arm modified chiral bisoxazoline (SaBOX) ligand, proceeded smoothly with broad substrate scope. 22 examples were studied, leading to corresponding products various functional groups in 41%–99% yields >99/1 dr 90%–96% ee. The resulting product two ester was mono‐reduced, giving excellent diastereoselectivity without loss enantiopurity.

Abstract An effective method to synthesize α‐functionalized furan and pyrrole derivatives was developed using 2‐alkoxy‐2,3‐dihydrofurans as modular precursors. This protocol featured a previously unreported tandem nucleophilic substitution/heteroaromatization reaction. Nucleophiles such indole, α‐oxoketene dithioacetal, trimethoxybenzene, dimethoxynaphthalene can react readily with afford five‐membered ring heterocycles in the presence of acid catalysts, copper bromide iron chloride. The...