1,2-Dipyridiniumditribromide-ethane (DPTBE) has been synthesized and explored as a new efficient brominating agent. The crystalline ditribromide reagent is stable for months and acts as a safe source of bromine requiring just 0.5 equiv for complete bromination. It has high active bromine content per molecule and shows a remarkable reactivity compared to other tribromide reagents toward various substrates by just grinding the reagent and substrates in a porcelain mortar at room temperature. No organic solvent has been used during any stage of the reaction for substrates giving product as solid. Product can easily be isolated by just washing the highly water soluble 1,2-dipyridiniumdibromide-ethane (DPDBE) from the brominated product. The spent reagent can be recovered, regenerated, and reused without any significant loss.

Stabilization energy, as proposed by Parr and Pearson (J. Am. Chem. Soc., 1983, 105, 7512) is decomposed into fragments. When the donor is not a perfect one and both the donor and the acceptor are ordinary organic molecules this decomposition is shown to provide energy fragments which, individually, can be correlated to the reaction rate of that particular step. It is shown how these different energy fragments can be used, together with the global electrophilicity value of the acceptor (w(A)), to locate the rate-determining step in multi-step reactions.

No abstract

No abstract

[Structure: see text] The products obtained by the reaction of benzoyl-3-phenylthioureas with bromine and enolizable ketones in the presence of triethylamine are not imidazole-2-thione derivatives as reported (Org. Lett. 2003, 5, 1657-1659) rather they are thiazolidene-2-imine derivatives.

No abstract

A facile and rapid synthesis of isocoumarin derivatives using a copper-catalyzed tandem C-C/C-O coupling strategy from readily available substrates is described. The reactions of a wide range of 2-iodo-N-phenyl benzamides and acyclic diketones as starting materials were investigated.

Direct N‐alkylation of primary amines to secondary/tertiary amines and of secondary amines to tertiary amines has been achieved in excellent yields by employing alkyl, benzylic and allylic halides in the presence of NaHCO3 in an aqueous medium at an elevated temperature. Amines of differentstereoelectronic nature react with ease with different halides. The selective formation of secondary amines and the formation of three different substituted tertiary amines are some of the interesting features of this methodology. Reaction in an aqueous medium, operationally convenient conditions, excellent yields and innocuous byproducts, and the absence of transition‐metal catalysts, expensive bases, solid supports and the formation of undesired quaternary ammonium salts makes this method a green chemical process. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)