Sulfur(IV)‐Mediated Unsymmetrical Heterocycle Cross‐Couplings

Despite the tremendous utilities of metal‐mediated cross‐couplings in modern organic chemistry, coupling reactions involving nitrogenous heteroarenes remain a challenging undertaking – coordination of Lewis basic atoms into metal centers often necessitate elevated temperature, high catalyst loading, etc. Herein, we report a sulfur (IV) mediated cross‐coupling amendable for the efficient synthesis of heteroaromatic substrates. Addition of heteroaryl nucleophiles to a simple, readily‐accessible alkyl sulfinyl (IV) chloride allows formation of a trigonal bipyramidal sulfurane intermediate. Reductive elimination therefrom provides bis‐heteroaryl products in a practical and efficient fashion.     

The Quest for β-Thiolactam Antibiotics

Thioketenes or thioketene equivalents give β-thiolactams in the reaction with C=N systems, but problems arise in the synthesis of highly functionalized derivatives. Therefore to obtain the thione analog of a bactam a thionation approach was chosen.     

ESCA STUDIES OF A DIPHOSPHENE

Abstract

The nature of the P[dbnd]P bond in E-bis(2,4,6-tri-tert-butylphenyl)diphosphene was studied by means of ESCA, indicating that the phosphorus 2p binding energy is the lowest among those for common organophosphorus compounds.     

Synthetic studies of spiroketal enol ethers: an unexpected oxidation by Martin’s sulfurane

In an attempt to synthesize a spiroketal enol ether natural product, we found that treatment of alcohol 5 with Martin’s sulfurane did not give the anticipated olefin, but instead afforded ketone 15 through an unprecedented oxidation.     

Preparation and Synthetic Applications of Sterically Hindered Secondary Amines

The preparation of sterically hindered secondary amino esters from the reaction of N-protected α-amino aldehydes and 3-, or 2-oxo esters with α-amino esters by reductive amination is described. The resulting amino esters were converted to the β-lactam or acylated to form N-acyl secondary amides.     

Difluorinated analogues of shikimic acid

Investigations into the quinate to shikimate transformation have been carried out, the results of which have been exploited in the synthesis of a novel difluoromethylene homologue of shikimic acid from (−)-quinic acid. Martin's sulfurane {Ph₂S[OC(CF₃)₂Ph]₂} was the reagent of choice for the key dehydration step of this synthesis. The results of investigations into the synthesis of the important natural product analogue, 6,6-difluoroshikimic acid are also reported.