1.1- Dithiolate derivatives, sulfur addition

Sulfur Addition. Since the initial studies of sulfur addition to anionic 1,1-dithiolate derivatives (Reaction 5) by Coucouvanis 14, 15)... 

From the reactions of sulfur and carbon disulfide with cyclic ketone-derived enamines (570-573) 3H-l,2-dithiole-3-thiones were obtained, whereas the addition of carbon disulfide to other enamines gave a-dithio-pyrones (574), through initial dimerization of the enamine. 

Synthesis. These macrocycles are prepared from seven-membered ring dinitrile complexes, 84a-84c (Scheme 17), which contain either methylene, sulfur or oxygen in the five position (129). These cyclic dinitriles are synthesized by alkylating maleonitrile dithiolate or derivatives thereof with the corresponding dihalide. The dinitriles 84a-84c can be cyclized in magnesium propoxide to form porphyrazines 85a (33%), 85b (19%), and 85c (27%) (Scheme 17), which can be demetalated with trifluoroacetic to form 86a-86c. Additionally, 86a has been remetalated with nickel (87a, 92%), copper (88a, 95%), and zinc (89a, 94%). The sulfur and oxygen derivatives 85b, 85c, 86b, and 86c are of low solubility and are not suitable for further manipulation. 

Prolonged heating of the addition compounds may result in the loss of sulfur, whereby dimeric products 139 are formed.197 Addition of one further mole of alkyne to the 2-thioacylmethylene-l,3-dithiole gives rise to spiranic thiopyrane derivatives 140.192... 

The attack of the acid (154) on the readily polarizable 1,2-dithiafulvene (155) corresponds to the extremely ready addition of electrophilic reagents to the simple and vinylogous heptafulvene derivatives, which are iso-n-electronic with 155. The opening of the dithiole rings in 156 and 158 under the pressure of the carbanionoid electron pair liberated by the proton abstraction and of the free electron pair on the sulfur, as well as the elimination of elementary sulfur and the intramolecular electrophilic attack of the mercaptide ion (157) on the 5-position to form 158, are simply the typical reactions of 1,2-dithioles that have already been discussed (Section II, B, 3). The reactivity of the 3-methyl group in 154 finds many parallels in the ease of condensation of the methyl-substituted pyridinium, pyrylium, thiopyrylium, and tropylium salts, and particularly... 

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