Ethers heterocyclic synthesis, intramolecular

Stereocontrolled synthesis of polycyclic ethers and related heterocycles via intramolecular reactions of allylstannanes 97YGK619. 

Intramolecular cyclization of 2-lithiobenzyl-2-halophenyl amines, ethers, and thioethers—Synthesis of phenanthridine, dibenzopyran, and dibenzothiopyran derivatives Having demonstrated the efficiency of this methodology for the preparation of indole derivatives, we prepared the 2-fluoro-phenyl ether and thioether 22 a, b to study their potential as substrates that could afford oxygen and sulfur heterocycles. However, treatment of 22 a, b with fBuLi afforded, after... 

Synthesis of novel bicyclic heterocyclic systems involving aziiidine ring formation has been described. The sodium salts of tosylhydrazones 11 decomposed by heating in benzene and gave aziridinopyrroloindoles 12 in yields up to 73% (equation 5) . Intramolecular cyclization of oxime ether 13 in the presence of base (for example, DBU) in acetonitrile afforded aziridinopyrrolidine 14 in yields up to 51% (equation 6) °. 

A variety of cycloaddition processes have been employed in the synthesis of oxygen and sulfur heterocycles. Intramolecular [ 4 + 4] and [ 2 +. 2] additions in suitably designed molecules, for example, have proved useful in this connection. Di-(a-naphthylmethyl)ether (371) is converted in this way to adducts 372 and 373,316 and similar transformations have been... 

Reaction of cyclic sulfates with intramolecular O-nucleophiles leads to cyclic ethers and other heterocycles (Table 1). For example, a hydrolysis of compound 39 has produced predominantly the cyclic alcohols 41 (Scheme 4) < 1995JA12873 >. When the reaction was buffered with pyridine, the sulfate ester 40 was isolated rather than the free alcohol. An alcohol function in an intermediate product may give a route to a polysulfate cascade cyclization, which has been successfully realized in the synthesis of poly(tetrahydrofurans) (Table 1) <1995JA12873>. 

Kita Y, Egi M, Okajima A, Ohtsubo M, Takada T, Tohma H (1996) Hypervalent iodine(lll) induced intramolecular cyclization of substituted phenol ethers bearing an alkyl azido side-chain - a novel synthesis of quinone imine ketals. Chem Commun 1491-1492 Kita Y, Egi M, Ohtsubo M, Saiki T, Takada T, Tohma H (1996) Novel and efficient synthesis of sulfur-containing heterocycles using a hypervalent iodine(lll) reagent. Chem Commun 2225-2226... 

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