Nitrogen-containing azetidines

The photoreactions of four-membered nitrogen containing heterocycles have been less well investigated and meaningful results are confined to certain azetidines and azetidinones. The photochemically induced rearrangement of azetines 148 to 1,4-diazepines 149 has been rationalized in terms of a process equivalent to a di-7t-methane rearrangement116 a more... 

Strain enormously influences the tendency for ring formation to give azetidines. Within the homologous series of azaheterocycles, the tendency for cyclization is smallest for the nitrogen-containing four-membered ring (5>3>6>7 = 4) (85JCS(P2)1345). 

Heterocyclic compounds hold a special place among pharmaceutically significant natural products and synthetic compounds. The synthesis of nitrogen-containing heterocycles such as substituted azetidines, pyrrolidines, piperidines, azepanes, 2V-substituted 2,3-dihydro-1//-isoindoles, 4,5-dihydropyrazoles, pyrazolidines and 1,2-dihydrophthalazines has been accomplished in an aqueous medium under the influence of MWs (Scheme 8.15).2" ... 

Synthesis of l-azabicyclo[1.1.0]butane, which contains both a four-membered and two three-membered nitrogen-containing rings ( ), follows the general route described above. As one would anticipate, ringopening reactions, one of which is illustrated, lead to products with an azetidine unit, rather than an aziridine unit. 

Systems containing One Nitrogen Atom Azetidines and Azetines. - A new synthesis of azetidine, allowing its preparation on a large scale, has been described. The new method involves the addition of sodium azide to acrolein and reduction of the addition product to... 

In 2012, Chen and coworkers developed the palladium-catalyzed intramolecular amination of C(sp )-H at y and 5 positions to synthesize a series of nitrogen-containing heterocycles [15], including azetidine (Scheme 2.11), pyrrolidines, and indolines. With the optimal conditions, using catalytic Pd(OAc)2, an oxidant (PhI(OAC)2, 2.5 equiv.) and an acid additive (AcOH) in toluene at llO C, Chen tested them on other picolinamide substrates bearing primary y-C(sp )-H bonds surprisingly, the seemingly unfavorable four-membered azetidine was obtained as the major product. It is possible that a Pd(IV) intermediate was formed via PhI(OAC)2 oxidation of the palladacycle intermediate because the subsequent C-N and C-O reductive elimination pathways would lead to the formation of the cyclized and acetoxylated product. It was also noteworthy that no P H elimination product was detected under the aforementioned reaction conditions. 

Several nitrogen-containing heterocyclic systems have been identified in the order Astrophorida. Of these, three azetidine derivatives isolated from species of the genus Penares are inhibitors of protein kinase C (Kobayashi et al, 1991a, 1996b Alvi, Jaspars, and Crews, 1994). 

Part 2 is devoted largely to four-membered rings containing nitrogen, for instance Azetidines, Azetines, Azetidinones (P-Lactams), Diazetidines, and Diazetines, as well as the three-membered ring Diaziridines. 

A somewhat similar ring closure in which a nitrogen anion attacks a halogenated carbon center is obtained in the anodic oxidation of dimethyl Q -(it -tosylaminoalkyl) malonates in methanol containing KI in an undivided cell. Aziridines, azetidines, and pyrrolidines may be formed in good yield [63]. 

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