A variety of nickel and copper complexes bearing the trifluoromethyl ligand have been prepared in order to quantify by electrochemical methods the redox potentials relative to their chloro and methyl counterparts. The effects of coordination number and geometry, as well as the oxidation state of the metal, on the relative ease with which trifluoromethyl complexes can be oxidized have for the first time been identified. In the d10 system [(NHC)Cu(X)] (NHC = N-heterocyclic carbene, X = methyl or trifluoromethyl), a single substitution of methyl for trifluoromethyl raised the oxidation potential of the organometallic complex by approximately +0.6 V versus the ferrocene/ferrocenium (Fc/Fc+) couple, a testament to the extreme electron-withdrawing properties of the trifluoromethyl ligand. The ΔE ox (methyl vs trifluoromethyl) for d8 nickel complexes were of similar magnitude; however the absolute oxidation potentials were dramatically dependent on the ligand (dippe = 1,2-bis(diisopropylphosphino)ethane vs BOXAM = bis(4-isopropyl-4,5-dihydrooxazol-2-yl)phenyl)amine).

[reaction: see text] The synthesis of an advanced intermediate in the synthesis of the title compound has been achieved. Key steps include an Ireland-Claisen rearrangement to install the C7 tertiary alcohol stereocenter, an SN2' reaction of an alkoxymethyl Cu reagent, and a diastereoselective Re-catalyzed allylic alcohol transposition.

A novel Ireland-Claisen approach to the putative structure of eupomatilone-6 is described. The rearrangement established the C3 and C4 stereocenters and concomitantly generated a vinyl epoxide. The C5 oxygen was installed by cyclization of the pentenoic acid carboxyl group onto the vinyl epoxide in an S(N)2' fashion to afford the C5-epi stereochemistry. The natural C5 stereochemistry was accessed via a substrate directed dihydroxylation.

The Ireland and ester enolate Claisen rearrangements of tertiary substituted bis-allylic esters derived from cyclohexenones afford pentenoic acids that possess tri- and tetrasubstituted alkylidenes with unprecedented levels of stereoselectivity. In some cases the higher energy exocyclic alkene is the major product. [reaction: see text]

The use of structural representations to convey spatial and chemical information is an integral part of organic chemistry. As a result, students must acquire skills to interpret and translate between the various diagrammatic forms. This article summarizes the skills sets, problem-solving strategies, and identified student difficulties in representational translation as presented in the literature and offers suggested methods for improving translational accuracy between dash–wedge diagrams and Newman projections.