Trown method

A complementary method was reported 3 years later by Hino, in which a readily enolizable diketopiperazine 48 was directly converted to the epidisulfide by deprotonation with sodium hydride and exposure to sulfur monochloride [38]. As with the Trown method, this method was limited to a specific class of substrates, namely, ones possessing a 1,3-dicarbonyl motif at each of the reactive centers, yet it has also seen subsequent applications in total synthesis [39, 40]. In 1972, Schmidt was able to significantly broaden the scope of the enolate thiolation method by introducing elemental sulfur as the electrophilic agent [41]. In contrast to Hino s method in which formation of a highly reactive, unstable adduct requires readily... 

In the 1970s, Kishi published a series of landmark papers [36] describing the total syntheses of ( )-dehydrogliotoxin (1973) [36b], ( )-sporidesmin A (1973) [36c], ( )-gliotoxin (1976) [36d], and ( )-hyalodendrin (1976) [36e] in which he employed a new method for epidithiodiketopiperazine synthesis (Scheme 9.4). Cognizant of the harsh conditions required in all of the sulfur incorporation methods developed at the time, it was determined that thiolation would be performed in the early stages of the syntheses. A dithiol intermediate obtained in a similar fashion to Trown s epidithiodiketopiperazine was protected as a dithioacetal, and after elaboration of this core diketopiperazine structure, the dithioacetal was unraveled under mild conditions in the final steps to afford the target epidisulfides. 

To synthesize coordination compounds with weak ligands, methods have been developed whereby water is either absent from the start or is removed through a chemical reaction/ In this contribution the preparation of coordination compounds of some divalent metals with nitromethane, ethanol, acetone, diphenyl sulfoxide, and acetonitrile are described. These descriptions are merely examples of simple general methods for the preparation of coordination compounds of Mg, Mn, Fe, Co, Ni, Cu, Zn, and Cd with weak ligands, such as those mentioned above and acetic acid, nitrobenzene, hydrogen cyanide, tetrahydrofurane, dioxane, diglyme (l,l-oxybis[2-methoxyethane]), 1,4,7,10,13,16-hexa-oxacyclooctadecane (18-trown-6), ethyl acetate, and 2,4-pentanedione (acetylacetone in the neutral ketonic form). ... 

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