9-(4-Hy­droxy-3,5-dimeth­oxy­phen­yl)-3,3,6,6-tetra­methyl-3,4,5,6,7,9-hexa­hydro-1H-xanthene-1,8(2H)-dione

In the title compound, C25H30O6, the two fused cyclo­hexa­none rings have envelope conformations, whereas the central pyran ring is roughly planar [mximum deviation = 0.045 (2) Å]. The pyran and benzene rings are almost perpendicular to each other, making a dihedral angle of 86.32 (2)°. In the crystal, molecules are linked via pairs of O—H⋯O hydrogen bonds, forming inversion dimers

An efficient transformation of ethers to N,Nâ²-disubstituted ureas in a Ritter type reaction

A simple, mild, and an alternative protocol for the preparation of N,Nâ²-disubstituted ureas from readily available ethers and cyanamides as starting materials is described. The protocol explores the reactivity of ether in a Ritter type reaction with cyanamide in the presence of BF 3·Et2O and resulting in the formation of N,Nâ²-disubstituted urea. Divinyl ether as well as MTBE (methyl tert-butyl ether) can be employed as ether components to afford allyl and tert-butyl ureas respectively. © 2012 Elsevier Ltd. All rights reserved

ChemInform Abstract: Synthesis of Boc‐ and Z‐Protected Amino Acid Fluorides Employing DAST as a Fluorinating Agent.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option

Facile Synthesis of N (alpha) -Protected Amino/Peptide Hydroxamic Acids Mediated by COMU

One-pot preparation of N (alpha) -protected amino/peptide hydroxamic acids from corresponding carboxylic acids is described using uronium-type coupling reagent COMU. The present protocol is simple and mild conditions are used. Thus the resulting hydroxamic acids are obtained in good yields without racemization

Staudinger/aza-Wittig Reaction to Access Nβ-Protected Amino Alkyl Isothiocyanates

A unified approach to access Nβ-protected amino alkyl isothiocyanates using Nβ-protected amino alkyl azides through a general strategy of Staudinger/aza-Wittig reaction is described. The type of protocol used to access isothiocyanates depends on the availability of precursors and also, especially in the amino acid chemistry, on the behavior of other labile groups towards the reagents used in the protocols; fortunately, we were not concerned about both these factors as precursor-azides were prepared easily by standard protocols, and the present protocol can pave the way for accessing title compounds without affecting Boc, Cbz and Fmoc protecting groups, and benzyl and tertiary butyl groups in the side chains. The present strategy eliminates the need for the use of amines to obtain title compounds and thus, this method is step-economical; additional advantages include retention of chirality, convenient handling and easy purification. A few hitherto unreported compounds were also prepared, and all final compounds were completely characterized by IR, mass, optical rotation, and 1H and 13C NMR studies

Synthesis of N-Fmoc-ProtectedAmino Alkyl Thiocyanates/Selenocyanates and their Applicationin the Preparation of 5-Substituted S/Se-Linked Tetrazoles

A novel class of N-Fmoc-protected amino alkyl thiocy- anates/selenocyanates has been prepared by thiocyanation/seleno-cyanation of the corresponding alkyl iodides. These thiocyanates/selenocyanates undergo a facile [2+3]-cycloaddition reaction with sodium azide to afford novel N-Fmoc amino alkylS/Se-linked tetra-zoles

T3P® (propylphosphonic anhydride) Mediated Conversion of Carboxylic Acids into Acid Azides and one-pot Synthesis of Ureidopeptides

A general, mild, efficient, and environmentally benign protocol, which makes use of T3P® as an acid activating agent for the direct synthesis of acid azides from carboxylic acids is described. Further, the protocol is employed for the one-pot synthesis of α-ureidopeptides starting from N-protected α-amino acids

An Efficient and Epimerization Free Synthesis of C-Terminal Arylamides Derived from α-Amino Acids and Peptide Acids via T3p Activation

A high yield and rapid synthesis of enantiomerically pure N α -protected amino/peptide acid arylamides using n-propylphosphonic anhydride (T3P) in presence of N-methylmorpholine is described. The generality of the reaction has been studied for various N α -protected amino acids with diverse range of aromatic amines and coumarin derivatives

One-pot synthesis of orthogonally protected dipeptide selenazoles employing Nα-amino selenocarboxamides and α-bromomethyl ketones

A simple and efficient protocol for the synthesis of selenazole containing dipeptidomimetics using Nα-amino selenocarboxamides and α-bromomethyl ketones is described. All the compounds made were isolated in good yields and fully characterized. © 2014 Elsevier Ltd