Estimation of optical rotation of γ-alkylidenebutenolide, cyclopropylamine, cyclopropyl-methanol and cyclopropenone based compounds by a Density Functional Theory (DFT) approach

Computing the optical rotation of organic molecules can be a real challenge, and various theoretical approaches have been developed in this regard. A benchmark study of optical rotation of various classes of compounds was carried out by Density Functional Theory (DFT) methods. The aim of the present research study was to find out the best-suited functional and basis set to estimate the optical rotations of selected compounds with respect to experimental literature values. Six DFT functional LSDA, BVP86, CAM-B3LYP, B3PW91, and PBE were applied on 22 different compounds. Furthermore, six different basis sets, i.e., 3-21G, 6-31G, aug-cc-pVDZ, aug-cc-pVTZ, DGDZVP, and DGDZVP2 were also applied with the best-suited functional B3LYP. After rigorous effort, it can be safely said that the best combination of functional and basis set is B3LYP/aug-cc-pVTZ for the estimation of optical rotation for selected compounds.

Titanocene(III) chloride mediated radical induced allylation of aldimines: formal synthesis of C-linked 4'-deoxy aza-disaccharide

Titanocene(III) chloride (Cp(2)TiCl) mediated radical induced allylation of aldimines for the preparation of homoallyl amines is described. The radical was generated from the allyl bromide using Cp(2)TiCl as the radical source. Formal synthesis of C(4)-C(5')-linked 4'-deoxy aza-disaccharide is demonstrated and a study toward the bicyclic skeleton of alkaloids was also accomplished. The radical initiator Cp(2)TiCl was prepared in situ from commercially available titanocene dichloride (Cp(2)TiCl(2)) and Zn dust in THF under argon.

Amine and thiazole substituted γ-butyrolactones from naturally occurring limonene

Substituted γ-butyrolactones are important structural motifs in several natural products and pharmaceuticals. In this paper, we report the synthesis of novel γ-butyrolactone amine and thiazole derivatives from naturally occurring limonene. Regioselective bromination followed by nucleophilic substitution with different amines and thiourea gave desired products in moderate yield.

Palladium(II)-Catalyzed Intramolecular Aminocarbonylation of endo-Carbamates under Wacker-Type Conditions

Pd(II)-catalyzed intramolecular aminocarbonylation of olefins bearing many types of nitrogen nucleophiles has been examined under two typical conditions: acidic conditions [conditions A, typically PdCl(2) (0.1 equiv) and CuCl(2) (3.0 equiv) under 1 atm of CO at room temperature in methanol] and buffered conditions [conditions B, typically PdCl(2) (0.1 equiv) and CuCl(2) (2.3 equiv) under 1 atm of CO at 30 degrees C in trimethyl orthoacetate]. Among nitrogen nucleophiles, endo-carbamates 7 display distinctive reactivity: endo-carbamates 7a-k smoothly undergo intramolecular aminocarbonylation under conditions B to furnish 4-[(methoxycarbonyl)methyl]-2-oxazolidinones 8a-k in good yields, while they would not undergo the expected reaction under conditions A. Other nitrogen nucleophiles (exo-ureas 1, endo-ureas 3, exo-carbamates 5, and exo-tosylamides 9), on the other hand, satisfactorily undergo aminocarbonylation only under conditions A to give rise to 2, 4, 6, and 10, respectively, in good yields. Under conditions B, they are unreactive and provide either the expected products in poor yields or intractable mixtures of products. On the basis of this contrasting reactivity between endo-carbamates and other nitrogen nucleophiles, the chemoselective aminocarbonylation of 7l-o has been achieved; aminocarbonylation takes place at the endo-carbamate moieties to furnish 8l-o exclusively under conditions B, and aminocarbonylation occurs at the exo-carbamate, exo-urea, and exo-tosylamide moieties to yield 13a-d exclusively under conditions A.