Sulfur-bridged polycycles

Scheme 4.6 Synthesis of sulfur-bridged polycycles via Pd-catalyzed dehydrogenative cyclization.

Imipramine (Tofranil). The development of Pheneragan, and N-amino-alkylphenothiazine, as an effective antihistaminic agent set the stage for a vast effort in molecular modification of both the polycyclic ring structure and the side chain. One of these modifications synthesized by Hafliger and Schindler (47, 95) represented the isosteric replacement of the sulfur bridge in Promazine by an ethylene bridge ... 

The organic chemical structural types believed to be characteristic of coals include complex polycyclic aromatic ring systems with connecting bridges and varied oxygen-, sulfur-, and nitrogen-containing functionalities. 

Reaction of di-/ -butylcyclopentadiene 76 with excess KOBuc in the presence of elemental sulfur leads to hitherto unknown cyclopentadienes 77 bridged by S-atoms via one or two dithioketal functionalities. Thus, polycyclic compounds with tetrathiepin fragment as well as eight- and more membered heterocyclic rings, containing sulfur and carbon atoms, were formed (Equation 14) <2000ICA184>. 

More than 40 cyclic polysulfanes have been investigated by X-ray diffraction on single crystals. These compounds are monocyclic or polycyclic. All ring sizes have been studied from 5 to 12 as well as 14, 16 and 20, and the number of sulfur atoms in the -S - unit varies from 3 to 11. There are also systems with two independent -S - units ( = 2-8) in one ring, bridged by carbon atoms. The following are leading references bis-... 

Among the homodetic, polycyclic, biologically-active tryptophan peptides, the toxins of the Amanita phalloides represent a special case [see reference 427) and 349) for a review]. In fact, the poisonous components of this deathcap, the phallotoxins and amatoxins (Fig. 9), both contain a cycloheptapeptide structure with an additional intramolecular covalent bond connecting the p-sulfur atom of a L-cysteine residue with the carbon atom in position 2 of the indole ring of a L-tryptophan residue. In the amatoxins the thioether bridge is oxidized to the sulfoxide (Fig. 9). 

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