A metal-free method for enantioselective conjugate addition of a dimethylphenylsilyl group to α,β-unsaturated carbonyls is reported. Transformations are catalyzed by a chiral N-heterocyclic carbene (NHC), performed in an aqueous solution (3:1 mixture of water and tetrahydrofuran) and are operationally simpler to perform than the NHC–Cu-catalyzed variant. The chiral catalyst is generated from an enantiomerically pure imidazolinium salt (prepared in three steps)and a common organic amine base (dbu). NHC-catalyzed processes proceed with 5.0–12.5 mol% catalyst loading at 22°C within 1–12 hours, affording the desired β-silyl carbonyls in 87:13 to>98:2 enantiomeric ratio and in 50% to >98% yield. Cyclic enones or lactones and acyclic α,β-unsaturated ketones, esters as well as aldehydes can be used as substrates.

The first broadly applicable metal-free enantioselective method for boron conjugate addition (BCA) to α,β-unsaturated carbonyls is presented. The C–B bond forming reactions are promoted in the presence of 2.5–7.5 mol % of a readily accessible C1-symmetric chiral imidazolinium salt, which is converted, in situ, to the catalytically active diastereo- and enantiomerically pure N-heterocyclic carbene (NHC) by the common organic base 1,8-diazabicyclo[5.4.0]undec-7-ene (dbu). In addition to the commercially available bis(pinacolato)diboron [B2(pin)2], and in contrast to reactions with the less sterically demanding achiral NHCs, the presence of MeOH is required for high efficiency. Acyclic and cyclic α,β-unsaturated ketones, as well as acyclic esters, Weinreb amides and aldehydes can serve as suitable substrates; the desired β-boryl carbonyls are isolated in up to 94% yield and >98:2 enantiomer ratio (er). Transformations are often carried out at ambient temperature. In certain cases, such as when the relatively less reactive unsaturated amides are used, elevated temperatures are required (50–66 °C); nonetheless, reactions remain highly enantioselective. The utility of the NHC-catalyzed method is demonstrated through comparison with the alternative Cu-catalyzed protocols; in cases involving a polyfunctional substrate, unique profiles in chemoselectivity are exhibited by the metal-free approach (e.g., conjugate addition vs reaction with an alkyne, allene or aldehyde).

Functionalized polycarbonates were synthesized by organocatalytic ring-opening polymerization (ROP) of a cyclic monomer with a pendant activated ester (MTC-OC6F5) followed by a postpolymerization modification with both small molecules and macromolecules. Controlled ROP to form homopolymers and diblock copolymers was realized using catalytic quantities of triflic acid. For the homopolymers, a linear relationship between [M]0/[I]0 and molecular weight (by GPC) demonstrated the living nature of the polymerization. Poly(MTC-OC6F5) was functionalized under mild reaction conditions with a variety of amines to obtain polymers with pendant primary, secondary, and tertiary amides. Graft polymers with a high grafting density of over 87% were synthesized using amine-terminated poly(ethylene glycol) of two different molecular weights (2 and 5 kDa). The preparation of poly(MTC-OC6F5) provides a means of accessing a wide range of functional polycarbonates with minimal synthetic steps. This new methodology for the formation of functionalized polycarbonates provides a simple and versatile platform for the synthesis of new and innovative materials.

An efficient Cu-catalyzed method for enantioselective boronate conjugate additions to trisubstituted alkenes of acyclic α,β-unsaturated carboxylic esters, ketones and thioesters is disclosed. All transformations are promoted by 5 mol % of a chiral monodentate NHC–Cu complex, derived from a readily available C1-symmetric imidazolinium salt, and in the presence of commercially available bis(pinacolato)diboron. Reactions are efficient (typically, 60% to >98% yield after purification) and deliver the desired β-boryl carbonyls in up to >98:2 enantiomer ratio (er). Reactions of unsaturated thioesters proceed with higher enantioselectivity (vs carboxylic esters or ketones), and the resulting products can be functionalized by Ag-mediated or Pd-catalyzed reactions that furnish the derived carboxylic ester or various ketones. Routine oxidation affords β-hydroxy ketones or carboxylic esters, ketone aldol products that cannot be otherwise prepared efficiently by an alternative catalytic enantioselective protocol.

We report an efficient and environmentally-friendly method of synthesizing polyurethanes in aqueous solution via an isocyanateand catalyst-free polymerization process. Five different polyurethanes were synthesized by first activating 1,6-hexanediol and poly(ethylene glycol) with bis( pentafluorophenyl)carbonate, and then polycondensing various ratios of the 1,6-hexanediol/poly-(ethylene glycol)-derived activated carbonates with JEFFAMINE.The polymerization process was confirmed by FTIR spectroscopy, 1 H NMR spectroscopy, and gel permeation chromatography (GPC).The melting temperature was linearly dependent on the 1,6-hexanediol/poly(ethylene glycol) ratio, increasing with greater poly (ethylene glycol) content, as confirmed by differential scanning calorimetry (DSC). Similarly, the degree of crystallinity was also directly proportional to the poly(ethylene glycol) content. † Electronic supplementary information (ESI) available: 1 H NMR spectra of Monomer B in D 2 O and DSC thermograms of all synthesized PU systems. See