Peri synthesis

A slightly more complex anti arrhythmic agent is pi rmentol (74). It is synthesized from 4-chloropropiophenone (72) by keto group protection as the dioxolane (with ethylene glycol and acid) followed by sodium iodide-mediated alkylation with cis 2,6-dimethyl pi peri dine to give 7. Deblocking with acid followed by addition of 2-1ithiopyridine completes the synthesis of pi rmentol (74). 

The synthesis of the peri methyl substituted benzo[6]thiepins, 58 and 59, was conveniently accomplished via the corresponding bicyclobutane derivatives 56 and 57 starting from 4-methyl-2 H-thiachromene (55). 

The key feature of the first total synthesis of (+)-homopumiliotoxin 223G 418 was a Lewis acid-induced, chelation-controlled propargylation of the trifluoroacetate salt of (. )-2-acetyl pi peri dine 415, derived from iV-Cbz-L-pipecolinic acid. Alkyne 416 thus formed was transformed after several steps into 417, which was cyclized by activation of the primary hydroxyl with the carbon tetrabromide-triphenylphosphine system to give the natural product (Scheme 98) <1998TL2149>. 

Synthesis of the ortho- and peri-fused pyrido[3,2,l- 1[l,3,2]benzodiazaphosphorine ring system was accomplished from the quinoline carboxamide derivative 197 by treatment with phosphoryl chloride <1978JHC1169, 1979JHC897>. The iV-chloropropyl derivative 198b could be transformed to the tetracycle 199 (Scheme 27) <1979JHC897>. 

Scheme 23. Synthesis of (-)-histrionicotoxine by a peri cyclic domino process...

Scheme 4 Thomas synthesis of the smaller fragment of lb. Reagents and conditions a ent-10, SnCl4,80% b p-nitrobenzoic acid, DEAD, Ph3P, 68% c NaOH, 94% d N-phenylselenenyl phthalimide, SnCl4,60% e Bu3SnH, AIBN, 89% f H2,10% Pd/C, 70% g Dess-Martin peri-odinane h NaCl02, NaH2P04 i z-Pr2NEt, BnBr, 81% from 27 j cone. aq. HCl, MeOH, 49%...

Peris E (2006) Routes to N-Heterocyclic Carbene Complexes. 21 83-116 Popp BV, Stahl SS (2007) Palladium-Catalyzed Oxidation Reactions Comparison of Benzo-quinone and Molecular Oxygen as Stoichiometric Oxidants. 22 149-189 Prashad M (2004) Palladium-Catalyzed Heck Arylations in the Synthesis of Active Pharmaceutical Ingredients. 6 181-204... 

The analogous principle of heterocyclization was used in the synthesis of naphtho[ c]pyran-2-one 261 from peri-methoxynaphthylacetic acid 260, which was obtained from 8-methoxytetralone (76JA4276). Pyronoan-... 

An idea similar to the previous reaction was applied to the synthesis of 2-functional-substituted naphtho[6c]pyrans 287 from peri-hydroxynaphthaldehydes 286 and a-halogenomethylene-active com-... 

One of the pathways to synthesis of a,a -dehydronaphtho[c f)-thiapyrans 383a-d includes step-by-step heterocyclization of peri-bis-bromomethyl, peri-bis-hydroxymethyl, or peri-bis-hydroxybenzyl-... 

The same principle was applied to the synthesis of the pyridazinone derivatives 417 with a fluorine nucleus (63ZOB1974). One can use peri-... 

Volume 51 of Advances consists of three chapters, V. V. Mezheritskii and V. V. Tkachenko (Rostov-on-Don, U.S.S.R.) review the synthesis of peri-annelated heterocycles, a large and interesting class which has not previously been treated in a systematic fashion. R. M. Acheson (Oxford, U.K.) provides the first detailed survey of 1-hydroxypyrroles and their benzo derivatives, compounds which show an interesting and unusual chemistry. Finally, B. A. Trofimov (Irkutsk, U.S.S.R.) describes the minifold preparative possibility for pyrroles from ketoximes and acetylenes, a reaction discovered by Trofimov and developed by him into a most important entry into pyrrole chemistry. 

In the course of the total synthesis of enmein, Fujita and co-workers (7) have discovered that the intramolecular cyclization of the enolate 23 of the corresponding tetracyclic keto-aldehyde at room temperature gave only ketol 24. However, when the same reaction is conducted at 60°C, thermodynamically controlled conditions prevail, and the epimeric product 25 is obtained. Inspection of molecular models indicates that the kinetically controlled product 24 is again the result of an anti peri planar arrangement of the enolate and the aldehyde double-bonds. Also, as in the previous examples, the isomer 25 comes from a synclinal arrangement of the reacting functional groups. 

The reaction of the peri-dichalcogenoaromatics with dichalcogenide dianions was also used in the synthesis of various mixed tetrachalcogenatet-racenes 45 (84ZOK891). 

The second approach to the synthesis of peri-bridged dichalcogenoles was applied for the first time to the preparation of naphtho[l,8-crf][l,2]-dichalcogenoles 46, obtained in low yields according to the scheme below (77JA255 78ANY382). 

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