2-BENZENESULFONYL CYCLIC ETHERS

Nucleophilic displacement of anomeric sulfones. 2-Benzenesulfonyl cyclic ethers undergo nucleophilic substitution with various organozinc reagents, particularly with those formed by reaction of ZnBr2 with Grignard reagents, rather than an alkyllithium. 

Substitution Reactions of 2-Benzenesulfonyl Cyclic Ethers Tetrahydro-2-(pbenylethynyl)-2H-pyran. 

SUBSTITUTION REACTIONS OF 2-BENZENESULFONYL CYCLIC ETHERS TETRAHYDRO-2-(PHENYLETHYNYL)-2H-PYRAN... 

Methods for forming carbon-carbon bonds at the anomeric position of cyclic ethers are important processes in organic synthesis. We have shown how lactols and their derivatives can be readily converted into the corresponding 2-benzenesulfonyl cyclic ethers.3-4 These versatile intermediates can then be transformed into the corresponding dihydropyrans,3 2-substituted dihydropyrans.4 spiroacetals,4 5 and tetrahydropyranyl ethers6 (Scheme 1). 

Nucleophilic Displacement of Anomeric Sulfones 2-Benzenesulfonyl cyclic ethers 106,108, and 110 undergo nucleophilic substitution with various organozinc reagents (Brown et al. 1989) (Scheme 7.41). 

Brown, D. S., Bruno, M., Davenport, R. J. and Ley, S. V. 1989. Substitution reactions of 2-benzenesulfonyl cyclic ethers with carbon nucleophiles. Tetrahedron 45 4293-4308. 

Brown, D S, Ley, S V, Vile, S, Preparation of cyclic ether acetals from 2-benzenesulfonyl derivatives a new mild glycosidation procedure. Tetrahedron Lett., 29, 4873-4876, 1988. 

Benzenesulfonyl chloride pyridine Cyclic ethers from diols s. 7, 355 stereospecific ring closure, tetrahydrofurans, C OH also with f. reagents, and from dimesylates preferably with NaOH, s. M. L. Mihailovid, S. Gojkovic, and 2. Cekovic, Soc. Perkin I 1972, 2460... 

The actual formation of hyperbranched material proceeds during the polymerization of 3,5-difiuoro-4 -hydroxydiphenyl sulfone in the presence of 3,4,5-trifluorophenylsulfonyl benzene or tris(3,4,5-trifiuorophenyl)phosphine oxide as a core molecule. Cyclic oligomers formed during this polymerization contribute to a low-molecular-weight polymer ranging from 3400 to 8400 Da. A triazin-based AB2 monomer has also been described [55]. This monomer is shown in Figure 7.11. A hyperbranched aromatic poly(ether sulfone) with sulfonyl chloride terminal groups has been prepared by the polycondensation of 4,4 -(m-phenylenedioxy)-bis-(benzenesulfonyl chloride). 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

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