Alkylsulfinyl- and Alkylsulfonylphthalazines

The preparation and more recently reported reactions of these potentially useful intermediates are illustrated in the following examples. 

Note Examples have been given already for the formation of sulfones by primary synthesis (Chapter 8), of the sulfones by arenesulfinolysis of halogenophthalazines (Section 10.3.4), and of both sulfoxides and sulfones by oxidation of alkylthiophthalazines (Section 12.1). A minor route is exemplified here. 

2-Phenyl-1,4(2//,3f/)-phthalazinedione (31) with chlorosulfonic acid at 0°C gave bis[p-(l,4-dioxo-l,2,3,4-tetrahydrophthalazin-2-yl)phenyl] sulfone (32) 

Note Examples have been given already for hydrolysis of the sulfones to phthalazinones (Section 11.1.1) and for their alcoholysis to alkoxyphthala-zines (Section 11.4.1). Other reactions are illustrated here. l-Phenyl-4-p-tolylsulfonylphthalazine (33) underwent cyanolysis to give 4-phenyl-l-phthalazinecarbonitrile (34) (KCN, MejNCHO, 140°C, 2h 96%). Such cyanolyses were also performed in dimethyl sulfoxide.  

3-Dibenzenesulfonyl-l,4(2//,3//)-phthalazinedione (40) suffered mono fesMZ-fonylation to give 2-benzenesulfonyl-l,4(2//,3/f)-phthalazinedione (41) [excess BusSnH, (=NCMe2CN)2 (catalyst), PhMe, reflux, N2 more catalyst J, after 30 min if incomplete (tic) 59%].  

---