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Henry Rzepa's Blog

Henry Rzepa's Blog
Chemistry with a twist
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CambridgeIsomeric ProductsReaction MechanismSimulationCiencias QuímicasInglés
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In the preceding post, I described a fascinating experiment and calculation by Bogle and Singleton, in which the trajectory distribution of molecules emerging from a single transition state was used to rationalise the formation of two isomeric products 2 and 3.  In the present post, I explore possible consequences of including a sodium cation (X=Na+ below) in […]

Interesting ChemistryReaction MechanismCambridgeChemistConformational AnalysisCiencias QuímicasInglés
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Years ago, I was travelling from Cambridge to London on a train. I found myself sitting next to a chemist, and (as chemists do), he scribbled the following on a piece of paper. When I got to work the next day Vera (my student) was unleashed on the problem, and our thoughts were published.

Chemical ITInteresting ChemistryHistoricalMPEGPeter SchreinerCiencias QuímicasInglés
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Back in 1994, we published the crystal structure of the molecule below (X=H), a putative anti-malarial drug called halofantrine. Little did we realise that a whole area of organo catalysis based on a thiourea catalyst with a similar motif would emerge a little later. Here is how the two are connected.

Baldwins RulesFree EnergyHydrogen Bond NetworkImmediate ProductReaction MechanismCiencias QuímicasInglés
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This is a continuation of the previous post exploring the transition state geometries of various types of ring closure as predicted by  Baldwin’s rules. I had dealt with bond formation to a trigonal (sp2) carbon; now I add a digonal (sp) example (see an interesting literature variation).

GeneralBaldwins RulesFree Energy BarrierImmediate ProductPotential Energy SurfaceCiencias QuímicasInglés
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The Baldwin rules for ring closure follow the earlier ones by Bürgi and Dunitz in stating the preferred angles of nucleophilic (and electrophilic) attack in bond forming reactions, and are as famous for the interest in their exceptions as for their adherence.

Interesting ChemistryAlbert SchatzCandidate For Its FormulaHistoricalLaboratory Of Selman WaksmanCiencias QuímicasInglés
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Streptomycin is an antibiotic active against tuberculosis, and its discovery has become something of a cause célèbre. It was first isolated on October 19, 1943 by a graduate student Albert Schatz in the laboratory of Selman Waksman at Rutgers University. I want to concentrate in this post on its molecular structure.