Maskless, Reusable Visible-Light Direct-Write Stamp for Microscale Surface Patterning.

We report a straightforward method for creating large-area, microscale resolution patterns of functional amines on self-assembled monolayers by the photoinduced local acidification of a flat elastomeric stamp enriched with photoacid. The limited diffusivity of the photoactivated merocyanine acid in poly(dimethylsiloxane) (PDMS) enabled to confine efficient deprotection of --butyloxycarbonyl amino group (-Boc) to line widths below 10 μm. The experimental setup is very simple and is built around the conventional HD-DVD optical pickup.

Fully Supramolecular Chiral Hydrogen-Bonded Molecular Tweezer.

Molecular tweezers are open-ended, cavity-possessing U-shaped molecular architectures with high potential for various applications in supramolecular chemistry. Their covalent synthesis, however, is often tedious and the structures obtained lack structural responsiveness beyond the limited conformational flexibility of the scaffold. Herein we present a proof-of-concept study on the design, synthesis, assembly, and transformations of a novel supramolecular construct─a fully noncovalent molecular tweezer.

An Enolate-Structure-Enabled Anionic Cascade Cyclization Reaction: Easy Access to Complex Scaffolds with Contiguous Six-, Five-, and Four-Membered Rings.

Catalyst-free addition of ketone enolate to non-activated multiple C-C bonds involves non-complementary reaction partners and typically requires super-basic conditions. On the other hand, highly aggregated or solvated enolates are not reactive enough to undergo direct addition to alkenes or alkynes. Herein, we report a new anionic cascade reaction for one-step assembly of intriguing molecular scaffolds possessing contiguous six-, five-, and four-membered rings, representing a formal [2+2] enol-allene cycloaddition.

Impact of t-butyl substitution in a rubrene emitter for solid state NIR-to-visible photon upconversion.

Solid state NIR-to-visible photon upconversion (UC) mediated by triplet-triplet annihilation (TTA) is necessitated by numerous practical applications. Yet, efficient TTA-UC remains a highly challenging task. In this work palladium phthalocyanine-sensitized NIR-to-vis solid UC films based on a popular rubrene emitter are thoroughly studied with the primary focus on revealing the impact of t-butyl substitution in rubrene on the TTA-UC performance.

Chemoselective Deprotection of Sulfonamides Under Acidic Conditions: Scope, Sulfonyl Group Migration, and Synthetic Applications.

Chemoselective acidic hydrolysis of sulfonamides with trifluoromethanesulfonic acid has been evaluated as a deprotection method and further extended to more complex synthetic applications. In contrast to conventional troublesome sulfonamide hydrolysis, a near-stoichiometric amount of acid was found to be sufficient to bring about efficient deprotection of various neutral or electron-deficient N-arylsulfonamides, whereas electron-rich substrates provided sulfonyl group migration products. The deprotection method developed is fully selective for N-arylsulfonamides, and the possibility to discriminate among various different sulfonamides is demonstrated.

Stimuli-controlled self-assembly of diverse tubular aggregates from one single small monomer.

The design and synthesis of new stimuli-responsive hydrogen-bonding monomers that display a diversity of self-assembly pathways is of central importance in supramolecular chemistry. Here we describe the aggregation properties of a simple, intrinsically C-symmetric enantiopure bicyclic cavity compound bearing a terminally unsubstituted ureidopyrimidinone fragment fused with a pyrrole moiety in different solvents and in the absence and presence of C and C guests. The tetrameric cyclic aggregate is selectively obtained in chlorinated solvents, where only part of the available hydrogen bonding sites are utilized, whereas in toluene or upon addition of C guests, further aggregation into tubular supramolecular polymers is achieved.

N-Tosyl-1,5,2,6-dithiadiazocane: a waste-free electrophilic sulfur reagent for the efficient synthesis of medium-ring S,N-heterocycles.

We report on the application of an eight-membered C2-symmetric sulfenamide derivative as a new convenient and highly reactive electrophilic sulfur-nucleophilic nitrogen synthon for the concise synthesis of medium-ring S,N-heterocyclic systems.

N-protected 1,2-oxazetidines as a source of electrophilic oxygen: straightforward access to benzomorpholines and related heterocycles by using a reactive tether.

A hitherto unknown reactivity of a strained four-membered heterocycle, 1,2-oxazetidine, is reported. When reacted with organometallic compounds, this reagent provides electrophilic oxygen with a nitrogen-terminated two-carbon-atom tether. The synthetic versatility of the products obtained was demonstrated in various transformations, leading to efficient synthesis of six-, seven-, and eight-membered heterocyclic systems of pharmaceutical importance.