Peri-annulation

Rearrangement of alkoxycarbonyl imidazole acryl azides in diphenyl ether at high temperatures afforded imidazo[l,5-c]pyrimidinone or imidazo[4,5-c]pyridinone derivatives <02TL5879>. Efficient synthesis of imidazopyridodiazepines from peri annulation in imidazo[l,2-a]pyridine has been described <02TL9119>. A convenient synthesis of 3,6-disubstituted-2-aminoimidazo[l, 2-a]pyridines has been published <02TL9051>. Novel 2,3-dihydroimidazo[2,l-h][l,3]oxazoles were prepared from intramolecular nucleophilic i/wo-substitution of 2-alkylsulfonylimidazoles <02S2691>. 4,4 -Bi-l//-imidazol-2-ones were efficiently synthesized from 5-amino-ot-imino-1 //-imidazole-4-acetonitriles and isocyanates <02JOC5546>. 

Novel carbon frameworks have been developed from polycyclic hydrocarbons. Thus, Kuck and coworkers143 have recently reported an unexpected tandem reaction, which formally consists of a condensation/cyclodehydrogenation sequence starting from triptidan-9-one 233 leading to the fn/wso-tetracyclic propellane 234 (Scheme 72). The reaction of the tribenzo[3.3.3]propellane ketone 233 with benzylhthium/TMEDA afforded an efficient one-pot peri annulation of a dihydronaphthalene (Scheme 72). The key step of this unexpected tandem reaction was determined to be a nucleophilic cychzation followed by hydride elimination. 

The specific feature of peri-annulation consists in the fact that the extraction of a heteromonocycle is impossible. Therefore, the minimum structural unit in this case is the tricyclic framework, for instance, (VII-IX). It is therefore obvious that peri-annulated heterocyclic systems possess qualitatively new structural features sufficient to separate these substances into an independent domain distinct from the array of the heteromonocyclic and ortho-fused heterocycles. 

Figure 2. Examples of aromatic and nonaromatic peri-annulated carbocyclic and heterocyclic systems...

Volume 95 of Advances in Heterocycle Chemistry commences with Part I of an update of Peri-Annulated Heterocyclic Systems by Valerii V. Mezheritskii (Rostov-on-Don State University, Russia). This chapter comprises an update of a review published in Volume 51 of our series (1990) by the same author together with V. V. Tkachenko. The present chapter is concerned with naphthalene derivatives with a four-membered peri-annulated heterocyclic ring. 

A peri-annulation between acylamino and chloro functions occurs in the presence of sodamide, and proceeds through a benzyne. 

A peri-fused system can be synthesized by diaryl copper-catalyzed ether coupling accomplished utilizing (CuOTf)2 PhMe in pyridine (Equation (21) (2004JOC4527)). This protocol produces several annulated ring systems and gives... 

The increased stabilization upon thienoannulation as compared to benzo-annulation may be caused by the more effective stabilization of the positive charge, by diminished angular ring strain, and by limited peri interactions between hydrogen atoms (due to the heteroatoms) and hence by nearly perfect planarity. 

A reversed carboxamide (containing a —CONHCHR CX)R chain) also cyclizes to a pyridin-2-one but this needs mildly basic followed by cyclodehy-drating conditions [3790]. Annulation of an TV-side-chain keto group to a peri-ring-C occurs when C-2 of an indole is blocked (cf. Section 1.2). 

Orthoesters annulate aminomethyl and amino groups to form a fused pyrimidine ring [2159]. Two amino groups in peri positions form a similar ring when treated with benzoic acid and. -diphenylphosphinyl-iV -methylpiperazine [3286] (see also Chapter 76, Section 1.1.A). 1,8-Naphthalenediamine is converted into perimidine by heating with 2-acylindanedione and 4-toluenesulphonic acid [2354]. Formic acid similarly cyclizes 4,5-quinolinediamine or the isomeric isoquinolinediamine in about 89VO yield [3338]. 

The aromatic lOic-electron heterocycle (84.1) may be synthesized by reaction of an azaindolizine with DM AD under dehydrogenating conditions [3465]. Another [8 + 2] cycloaddition is that of indolizines with DMAD at the 3,5-positions in the presence of palladium as dehydro nator [3571]. Very reactive nitriles annulate the peri positions of an indene in an [8 -I- 2] addition [3160]. 

A bromoacetylamino group is annulated to a peri-placed ring-nitrogen by heating with t-butoxide in isopropanol. 

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