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Tussilagine and isotussilagine are synthesized through the coupling reactions of N,N -disubstituted β-amino-esters with methyl pyruvate and Mitsunobu reactions as key steps.

A new ternary chromium sulfide, BaCrS2, was synthesized. This solid state compound crystallizes in the orthorhombic, centrosymmetric space group Pmmn (No. 59) with a = 4.2606(6) A, b = 4.7944(7) A, c = 9.443(1) A, V = 192.89(5) A3, and Z = 2. The solid is similar to a previously known structure BaNiS2 in which the Ni atom is coordinated to five sulfur atoms in a square pyramidal fashion. In BaCrS2, the square pyramid distorts such that the two S(basal)−Cr−S(basal) angles are no longer equal. Thus the BaCrS2 solid is orthorhombic whereas BaNiS2 is tetragonal. The distortion from the square pyramidal coordination in the title compound is traced to the broken degeneracy of the dxy and dxz set by a computational analysis.

Condensation of enantiopure β-amino ester 2a with methyl pyruvate provides two diastereoisomers 3 and 4. Both 3 and 4 are subjected to hydrogenation followed by cyclization producing pyrrolidinones 5 and 8. From 5 and 8 isotussilagine and tussilagine are obtained respectively, by using a Mitsunobu reaction as a key step. In a similar manner, (–)-petasinecine is synthesized from the condensation product of 2b with ethyl glyoxalate.

A nonstoichiometric ternary vanadium sulfide, BaxV6S8 (x = 0.41−0.48), was synthesized. This solid-state compound crystallizes in the hexagonal space group P63/m (no. 176) with a = 9.2080(3) A, c = 3.3169(2) A, V = 243.55(2) A3, and Z = 1. The structure of this solid is similar to that of its parent compound V3S4, consisting of face-sharing, distorted octahedral VS6 units. A superconducting transition of the solid at approximately 2.5 K was observed. A computational analysis of the electronic structure using the extended Huckel method is presented.