Thiophosgene reaction with 1,3-dienes

Like 2-aminopyridines and 2-aminopyrimidine, 2-aminopyrazine (39) (Scheme 29) has been converted into the nitroso compound (121) by reaction with dimethyl sulfide and NCS followed by deprotonation of the resulting sulfonium salt with sodium methoxide to the 5, 5-dimethylsulfilimine and then oxidation with MCPBA <82JOC552>. The extremely reactive nitrosopyrazine (121) condenses with 1,3-dienes to give 3,6-dihydro-1,2-oxazines and with aromatic amines in the presence of acid to gives azo compounds, and is smoothly oxidized with ozone or sodium hypochlorite to 2-nitropyrazine (122). Methyl 3-aminopyrazinecarboxylate reacts with thiophosgene to produce the... 

Thiophosgene reacts with cyclohexa-1,3-diene to yield the adduct (17 R = Cl), which can be hydrolysed to the ketone or reduced with lithium aluminium hydride to the bicyclo[2,2,2]oct-5-ene. The related sulphone (18), made by addition of dimethyl acetylenedicarboxylate to 3-phenyl-2H-thiopyran 1,1-dioxide, undergoes a reverse Diels-Alder reaction at 220 C,... 

A sterically hindered (2,4,6-tri-t-butylphenyl)[bis(trimethylsilyl)]phosphine (9), whose crystal structure has been reported84, was utilized to form a 1-phosphabuta-l,3-diene (equation 67)36. Mes -substituted phosphaketene was obtained from the reaction of 9 with phosgene (equation 68)4. Reaction of 9 with thiophosgene afforded dimeric phosphathioketene, [Mes P=C=S]2 (equation 69)85. A."V3-Dithioxophosphorane was also isolated by introduction of the bulky substituent (equation 70)86. 

Most of the compounds were synthesized from the reaction products of cyclic dienes with (a) thiophosgene or (b) chlorosulfonylisocyanate. Analogous bicyclic amidoxime derivatives were devoid of activity. 

The bicyclic thiolhydroximidates were prepared by the reaction of hydroxylamine with gem-dichlorothiabicycloalkenes which are readily obtained by the Diels-Alder reaction of thiophosgene with the appropriately substituted cyclic 1,3-diene (8,2). A more detailed report of this chemistry will be published elsewhere. 

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