Non-fluorinated vinyldiazo compounds with trans-configuration irrespective of the nature of 3-R(1)-substituent (R(1) = H, Me, TBSO) even under ambient conditions easily cyclize to produce pyrazoles, while cis-stereoisomers undergo similar ring closure only at elevated temperatures or decompose to produce vinyloxocarbene reaction products. The 3-CF3-substituted analogues with cis- or trans-confi...

Stereoselective total syntheses of the four stereoisomeric forms of guaiacylglycerol 8-O-4'-coniferyl ether, viz., compounds 1, ent-1, 2, and ent-2, have been established. The key step involves an Evans/Seebach auxiliary-controlled and syn-selective aldol process followed, in the reaction sequences leading to the anti-compounds, by a Mitsunobu reaction involving a benzylic alcohol residue. The ...

In continuation of studies on the stereochemical specificity of serum reactions, antigens were examined containing the acyl radicals of the levo-, dextro-, and meso-tartaric acids. It was found that in this case also, immune sera can readily be obtained which differentiate sharply the three antigens identical in every other respect but possessing stereoisomeric groups. Since the tartaric acids ...

Disclosed herein is a stereoselective method for the synthesis of 2,3-furan fused carbocycles bearing adjacent quaternary and tertiary carbon stereocenters. The chemistry is based on an asymmetric addition of b-ketoesters to 2-(1-alkynyl)-2-alkene-1-ones catalysed by natural cinchona alkaloids followed by a silver-catalysed intramolecular cycloisomerisation. By exploiting the distinct catalysis...