Prying open a Thiele cage: discovery of an unprecedented extended pinacol rearrangement

Aza-pinacol rearrangement: acid-catalyzed rearrangement of aziridines to imines.

A series of di-, tri-, and tetra-substituted N-tosylaziridines [N-(toluene-p-sulfonyl)aziridines] 1, prepared by aziridination of the corresponding alkenes with N-[(tolyl-p-sulfonyl)imino]phenyliodinane (TsN = IPh), was found to undergo a BF3-catalyzed rearrangement (aza-pinacol rearrangement) under mild conditions to give the corresponding N-tosylimines 2 generally in satisfactory yields.

Organocatalytic Enantioselective Vinylogous Pinacol Rearrangement Enabled by Chiral Ion Pairing.

An enantioselective pinacol rearrangement of functionalized (E)-2-butene-1,4-diols was developed. In the presence of a catalytic amount of a chiral BINOL-derived N-triflyl phosphoramide, these 1,4-diols rearranged to β,γ-unsaturated ketones in excellent yields and enantioselectivities. The formation of a chiral ion pair between the intermediary allylic cation and the chiral phosphoramide anion ...

A Computational and Experimental Investigation of the Pinacol Coupling and Rearrangement Reactions

Enantioselective halogenative semi-pinacol rearrangement: a stereodivergent reaction on a racemic mixture.

An efficient, quantitative deracemization strategy for optically inactive allylic cycloalkanols has been achieved using the biphasic halogenative semi-pinacol reaction protocol. The resultant β-halo spiroketones, containing three contiguous stereogenic centers, were easily recovered with high diastereomeric and enantiomeric purities following conventional silica gel chromatography. The opticall...

E-Voting and Forensics: Prying Open the Black Box

Over the past six years, the nation has moved rapidly from punch cards and levers to electronic voting systems. These new systems have occasionally presented election officials with puzzling technical irregularities. The national experience has included unexpected and unexplained incidents in each phase of the election process: preparations, balloting, tabulation, and reporting results. Quick t...