Nathaniel J. Wallock

Reactivity of (2-alkenyl-3-pentene-1,5-diyl)iron complexes: preparation of functionalized vinylcyclopropanes and cycloheptadienes

The reactivity of (2-alkenyl-3-pentene-1,5-diyl)iron complexes toward olefin metathesis, cycloaddition, and mild oxidations (MnO 2 or mCPBA) was examined. Cycloaddition reactions were observed to occur with modest diastereoselectivity (33-63% de). Decomplexation of the (3-pentenediyl) ligand may be accomplished by oxidation with either CAN or alkaline hydrogen peroxide to afford vinylcyclopropanecarboxylates or divinylcyclopropanecarboxylates. Reduction of the latter, followed by Cope rearrangement generates cycloheptadienylmethanols. These studies demonstrate that (2-alkenyl-3-pentene-1,5-diyl)iron complexes can serve as organometallic scaffolds for the preparation of a wide variety of structural motifs containing up to 5 contiguous stereocenters.

Synthesis of cyclopropanes via organoiron methodology: stereoselective preparation of cis-2-(2′-carboxycyclopropyl)glycine

A stereoselective route to cis-2-(2′-carboxycyclopropyl)glycine has been developed. exo-Nucleophilic addition to the (bicyclo[5.1.0]octadienyl)iron(1+) cation establishes the relative stereochemistry at the cyclopropane ring and the α-stereocenter. Subsequent removal of the metal and cleavage of the cyclic diene gave the protected target 10, which upon hydrolysis gave 1.

Crystal and molecular structure of N-(bicyclo[5.1.0]octa-3,5-dien-2-yl)phthalimide, C16H13NO2

Single crystal X-ray diffraction analysis of the title compound revealed that the phthalimide substituent was endo with respect to the bicyclic ring system.

Crystal structure of cis-2-(2-carb­oxy­cyclo­prop­yl)glycine (CCG-III) monohydrate

The title compound is an example of a ‘false conglomerate’ with two molecules of opposite handedness in the asymmetric unit. Each molecule exists as a zwitterion, with proton transfer from the amino acid carboxylic acid group to the amine group. In the crystal, the components are linked by N—H⋯O and O—H⋯O hydrogen bonds, generating (100) sheets.

Synthesis of Cyclopropanes via Organoiron Methodology: Preparation and Rearrangement of Divinylcyclopropanes - Studies Directed toward the Synthesis­ of Hydroazulenes

Addition of alkenyl Grignard reagents to (1-methoxycarbonylpentadienyl)iron(1+) cation generates the corresponding (2-alkenylpent-3-en-1,5-diyl)iron complexes. Oxidatively induced-reductive elimination of these complexes gives divinylcyclopropanes which can undergo subsequent Cope rearrangement to give 1,4-cycloheptadienes.