SYNTHESIS OF N-HETEROCYCLES VIA PALLADIUM-CATALYZED REDUCTIVE CYCLIZATION REACTIONS OF NITROARENES AND NITROALKENES USING FORMIC ACID DERIVATIVES AS CO SURROGATES

The reductive cyclization reaction of nitroarenes to produce N-heterocycles has been ‎investigated for more than four decades using CO as a cheap reductant, but it is still a ‎fascinating area for research and advancements. On the other hand, using toxic CO gas is ‎accompanied by many disadvantages. Thus, the thesis focuses on the use of phenyl formate and ‎formic acid as cheap, affordable, efficient and safe in-situ CO surrogates for the reductive ‎cyclization of various nitroarenes. Notably, in most cases, the isolated yield of the desired ‎heterocycle was higher than those previously obtained for the same reaction when gaseous CO ‎had been employed, which indicates that the use of these surrogates should not necessarily be ‎considered a second choice when the use of CO gas is not possible. A cheap thick-walled glass ‎‎“pressure tube” can be used instead of less-available autoclaves.‎