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N1-Methyl-N4-Boc-benzo[e][1,4]diazepine-2,5-diones were prepared in good yield and high stereochemical purity from five amino acids. Upon deprotonation, these compounds undergo ring contraction to the corresponding quinolone-2,4-diones with high enantioselectivity, providing efficient entry to a potentially useful drug scaffold. Mechanistic commentary and comparisons to related reactions are provided.

trans-Diepoxide 1 is well-known to react with aliphatic amines and the azide ion to give exclusively the 1,3-diol products. However, we observed that by judicious choice of conditions, reaction with anilines can give predominantly the 1,3-diol (3) or the heretofore rarely seen C(i)-symmetric 1,4-diol (4). Synthesis of an unsymmetrical 1,4-diol from two different anilines is also demonstrated. These studies demonstrate that an intramolecular anilino-NH hydrogen bond donor can direct Fürst-Plattner epoxide opening.

[structure: see text]. Magnesium-bromine exchange on enantiopure cyclopropyl bromonitrile 5 at -100 degrees C for 1 min followed by a D2O quench gives the deuterionitrile in 81% ee (retention); additional trapping experiments establish t(1/2)(rac) = 11.4 h at -100 degrees C. These experiments provide the first glimpse into the stereochemical aspects of Mg-Br exchange. The intermediate formed is the first metalated nitrile demonstrated to possess macroscopic configurational stability.

[reaction: see text] Proline-derived 1,4-benzodiazepine-2,5-diones are extremely useful scaffolds in medicinal chemistry. In this paper, we describe a protocol for retentive C3 alkylation of these materials, thus accomplishing the direct synthesis of enantiopure quaternary 1,4-benzodiazepine-2,5-diones. The high enantioselectivities (up to 99.5%) are attributed to memory of chirality.

In HMPA-THF solution, lithiated 1-naphthylacetonitrile undergoes highly syn-selective addition to aromatic aldehydes, providing the first access to such syn-aldols. Syn-selectivity is also observed with two other arylacetonitriles. Aldolate equilibration and crossover experiments demonstrate that HMPA promotes retro-aldol reaction and that aldol diastereoselectivity under these conditions is thermodynamically controlled.