Reactivity of Substituents Attached to Ring Nitrogens

The reactivity of substituents attached to ring nitrogens was only briefly discussed in CHEC-I because it was considered in most cases to be similar to that of carbon linked substituents 84CHEC-i(3B)i . The most important reaction, deoxygenation of V-oxides, was summarized many methods are successful but the reagent must be selected to minimize side reactions, such as reductive dehalogenation. 

While this part was only briefly addressed in CHEC(1984) 1984CHEC(2)1 , it substantially expanded in CHEC-11(1996) 1996CHEC-II(6)1 . Since 1995 interesting advances have been made in this area and therefore new sections have been included in this edition. 

Important advances have been made in the identification of suitable N-2 protection groups for pyridazin-3(2/7)-ones since CHEC-II(1996) appeared 1996CHEC-II(6)1 . 

X = CI, Br K2CO3, MeOH, rt NaN3, MeOH, reflux MeNHz HCI, NEt3 MeOH, reflux 

Besides removal of alkyl-based groups located at the N-2 of a pyridazin-3(27/)-one also real reactions in the side chain appeared. Pyridazinium ylides, obtained via deprotonation of iV-alkylpyridazinium salts, have been reacted with phenyl isocyanates and benzenediazonium salts 2002MI287, 1997T4411 . As discussed in Section 8.01.5.7.2 1,3-dipolar cycloaddition with ethyl acrylate and ethyl propiolate were also studied. 

The synthesis of 2-chloropyridazin-3(2//)-ones has been discussed in Section 8.01.5.5.5. They can be used as mild electrophilic chlorinating agents for active methylene compounds in the presence of acids in water or Lewis acids in CH2CI2 200581136 . 

---

Reactivity of Substituents Attached to Ring Nitrogen Atom. 252... 

Reactivity of substituents attached to ring nitrogen atom 105... 

REACTIVITY OF SUBSTITUENTS ATTACHED TO RING NITROGEN ATOMS... 

---