Selective Peptide Chain Extension at the N-terminus of Aspartic and Glutamic Acids Utilizing 1-(N-protected-alpha-aminoacyl)benzotriazoles

Chemical Biology & Drug Design. Jul, 2006  |  Pubmed ID: 16923024

Diverse N-protected di-(3a-d, 3a + a', 5a-d, 5d + d', and 7a-g) and tripeptides (10a-h) were synthesized under mild reaction conditions in good yields (65-97%) by acylation with 1-(N-protected-alpha-aminoacyl)benzotriazoles of the amino groups of free aspartic and glutamic acids. Complete retention of chirality was demonstrated by parallel experiments involving D-Ala, L-Ala, and DL-Ala for the preparation of dipeptides and tripeptides, and supported by NMR and HPLC analyses.

Selective Peptide Chain Extension at the C-terminus of Aspartic and Glutamic Acids Utilizing N-protected (alpha-aminoacyl)benzotriazoles

Chemical Biology & Drug Design. Jul, 2006  |  Pubmed ID: 16923025

Aspartic and glutamic acids were selectively extended at each of the alternative C-terminals under mild conditions to afford diverse natural and unnatural N-protected dipeptides and tripeptides in yields of 73-96%. The reactions between N-protected (alpha-aminoacyl)benzotriazoles and free amino acids or dipeptides proceeded with complete retention of chirality as supported by parallel experiments involving D-Ala, L-Ala, and DL-Ala in the preparation of dipeptides and tripeptides, monitored by NMR and HPLC analyses.

Inkless Microcontact Printing on Self-assembled Monolayers of Fmoc-protected Aminothiols

Journal of the American Chemical Society. Nov, 2007  |  Pubmed ID: 17949005

One-pot Synthesis of Diverse 4-di(tri)fluoromethyl-3-cyanopyridine-2(1H)-thiones and Their Utilities in the Cascade Synthesis of Annulated Heterocycles

Journal of Combinatorial Chemistry. Mar-Apr, 2008  |  Pubmed ID: 18269251

Diverse substituted 4-di(tri)fluoromethyl-3-cyanopyridine-2(1H)-thiones were synthesized via the Claisen condensation of alpha-methyl(methylene)ketones with di(tri)fluoroacetate, followed by the immediate Thorpe-Guareschi reaction of the preformed di(tri)fluoromethyl-1,3-diketones with cyanothioacetamide. The procedure allows facile synthesis of the di(tri)flouromethylated pyridine-2(1H)-thiones in 50-95% yields, without the need for isolation and purification of intermediates. Resultant 4-di(tri)fluoromethyl-3-cyanopyridine-2(1 H)-thiones were subsequently utilized in domino reactions to produce first various substituted thieno[2,3-b]pyridines and, then, thienopyridines polyannulated with pyridine, pyrimidine, benzodiazocine, diazepine, and pyran rings.

New Convenient Four-component Synthesis of 6-amino-2,4-dihydropyrano[2,3-c]pyrazol-5-carbonitriles and One-pot Synthesis of 6'-aminospiro[(3H)-indol-3,4'-pyrano[2,3-c]pyrazol]-(1H)-2-on-5'-carbonitriles

Journal of Combinatorial Chemistry. Sep-Oct, 2009  |  Pubmed ID: 19711896

This report describes a new four-component synthesis of substituted and spiro-conjugated 6-amino-2H,4H-pyrano[2,3-c]pyrazol-5-carbonitriles directly from aromatic aldehydes or heterocyclic ketones, malononitrile, beta-ketoesters, and hydrazine hydrate. The method provides a convenient one-pot route toward divers 2,4-dihydropyrano[2,3-c]pyrazoles, whereas a modified one-step sequential protocol gives access to spiro[indoline-3,4'-pyrano[2,3-c]pyrazol]-2-ones.

Combinatorial Synthesis of Substituted Thieno[3,2-b]pyridines and Other Annulated Heterocycles Via New S(N)2-->Thorpe-Ziegler-->Thorpe-Guareschi Domino Reactions

Journal of Combinatorial Chemistry. Jan-Feb, 2010  |  Pubmed ID: 19928775

Inkless Microcontact Printing on SAMs of Boc- and TBS-protected Thiols

Nano Letters. Jan, 2010  |  Pubmed ID: 19950928

We report a new inkless catalytic muCP technique that achieves accurate, fast, and complete pattern reproduction on SAMs of Boc- and TBS-protected thiols immobilized on gold using a polyurethane-acrylate stamp functionalized with covalently bound sulfonic acids. Pattern transfer is complete at room temperature just after one minute of contact and renders sub-200 nm size structures of chemically differentiated SAMs.

Catalytic Microcontact Printing on Chemically Functionalized H-terminated Silicon

Langmuir : the ACS Journal of Surfaces and Colloids. Feb, 2010  |  Pubmed ID: 19950970

We report a novel inkless soft lithographic fabrication protocol that permits uniform parallel patterning of hydrogen-terminated silicon surfaces using catalytic elastomeric stamps. Pattern transfer is achieved catalytically via reaction between sulfonic acid moieties covalently bound to an elastomeric stamp and a Boc-functionalized SAM grafted to passivated silicon. The approach represents the first example of a soft lithographic printing technique that creates patterns of chemically distinctive SAMs on oxide-free silicon substrates.

Patterning NHS-terminated SAMs on Germanium

Langmuir : the ACS Journal of Surfaces and Colloids. May, 2011  |  Pubmed ID: 21504221

Here we report a simple, robust approach to patterning functional SAMs on germanium. The protocol relies on catalytic soft-lithographic pattern transfer from an elastomeric stamp bearing pendant immobilized sulfonic acid moieties to an NHS-functionalized bilayer molecular system comprising a primary ordered alkyl monolayer and a reactive ester secondary overlayer. The catalytic polyurethane-acrylate stamp was used to form micrometer-scale features of chemically distinct SAMs on germanium. The methodology represents the first example of patterned SAMs on germanium, a semiconductor material.

Soft-lithographic Approach to Functionalization and Nanopatterning Oxide-free Silicon

Langmuir : the ACS Journal of Surfaces and Colloids. May, 2011  |  Pubmed ID: 21520913

We report a simple, reliable high-throughput method for patterning passivated silicon with reactive organic monolayers and demonstrate selective functionalization of the patterned substrates with both small molecules and proteins. The approach completely protects silicon from chemical oxidation, provides precise control over the shape and size of the patterned features in the 100 nm domain, and gives rapid, ready access to chemically discriminated patterns that can be further functionalized with both organic and biological molecules.