Note that the CO stretch of ethyl acetate (1752) is at a higher wavelength than that of the, -unsaturated ester ethyl benzoate (1726).

A Novel Approach to the Synthesis of Tetrahydrofuran and Tetrahydropyran Derivatives) ) by Dieter Seebach3), Manat Pohmakotr4) 5), Christian Schregenberger6), Beat Weidmann, Raghao S.

The t-butyl and a-hydroxy-ketones are cleaved to give nitriles, amides, carboxylic acids and esters (Formulae 16-25).

The reagents 1 allow to syn- thesize products with distant functional groups in one step (cf.

Formulae 26-30); they correspond to the d5-synthons 31-33; in Table 6, they are compared with other ds-reagents.

Introduction. - In connection with our work on reactivity umpolung with dian- ions) we discovered, that the novel reagents of type 1 can be generated by double deprotonation in the a- and 8-position of 56-unsaturated carbonyl compounds and their dithio-analogues.

Present address: Department of Chemistry, Faculty of Sciences, Mahidol University, Rama 6 Road, Bangkok 4, Thailand.

M. P., Universitat Giessen, 1978.

Part of the projected Ph.

D. thesis of Ch. S., ETH Zurich.

On leave of absence from University of Poona, India, 197980.

See references on redox umpolung in our review article 2.

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Cyclic Ester With Lda And Ch3Ch2I