Pyrrole-Protected ß-Aminoalkylzinc Reagents for the Enantioselective Synthesis of Amino-Derivatives.

Chiral ß-aminoalkylzinc halides were prepared starting from optically pure commercial ß-amino-alcohols. These amino-alcohols were converted to the corresponding N-pyrrolyl-protected alkyl iodides which undergo a zinc insertion in the presence of LiCl (THF, 25 °C, 10-90 min). Subsequent Negishi cross-coupling or acylation reactions with acid chlorides produced amino-derivatives with retention of chirality. Diastereoselective CBS-reductions of some prepared N-pyrrolyl-ketones provided 1,3-subsituted N-pyrrolyl-alcohols with high diastereoselectivity. Additionally, a deprotection procedure involving an ozonolysis allowed the conversion of the pyrrole-ring into a formamide without loss of optical purity.

Late-Stage Functionalization of Peptides and Cyclopeptides Using Organozinc Reagents.

We report a new late-stage functionalization of small peptides and cyclopeptides relying on the Negishi cross-coupling of readily prepared iodotyrosine- or iodophenylalanine-containing peptides with aryl-, heteroaryl-, and alkylzinc pivalates or halides. In silico and in vitro determinations of membrane permeability parameters of the modified cyclopeptides showed that in most cases, the solubility was improved by the introduction of polar pyridyl units while the cell-membrane permeability was maintained.

Iron-Catalyzed Acylation of Polyfunctionalized Aryl- and Benzylzinc Halides with Acid Chlorides.

FeCl2 (5 mol %) catalyzes a smooth and convenient acylation of functionalized arylzinc halides at 50 °C (2-4 h) and benzylic zinc chlorides at 25 °C (0.5-4 h) with a variety of acid chlorides leading to polyfunctionalized diaryl and aryl heteroaryl ketones.

Energetic Materials Based on 5,5'-Diamino-4,4'-dinitramino-3,3'-bi-1,2,4-triazole.

A simple and straightforward synthesis of 5,5'-diamino-4,4'-dinitramino-3,3'-bi-1,2,4-triazole by the selective nitration of 4,4',5,5'-tetraamino-3,3'-bi-1,2,4-triazole is presented. The interaction of the amino and nitramino groups improves the energetic properties of this functionalized bitriazole. For a deeper investigation of these properties, various nitrogen-rich derivatives were synthesized. The new compounds were investigated and characterized by spectroscopy ((1)H and (13)C NMR, IR, Raman), elemental analysis, mass spectrometry, differential thermal analysis (DTA), X-ray analysis, and impact and friction sensitivities (IS, FS). X-ray analyses were performed and deliver insight into structural characteristics with which the stability of the compounds can be explained. The standard enthalpies of formation were calculated for all compounds at the CBS-4M level of theory, revealing highly positive heats of formation. The energetic performance of the new molecules was predicted with the EXPLO5 V6.02 computer. A small-scale shock reactivity test (SSRT) and a toxicity test gave a first impression of the performance and toxicity of selective compounds.