Starting Material 2,7-Dihetero-twistanes

Analogously to the isotwistanes (see 3.2.3.) twistanes with only one leaving group R -C(10) (R = H, type G 45) were subjects for studies of neighboring group participation. The results are listed in Table 4. 

Starting material G44 Y(7) X(2) R Reagents R3 Isotwistane G47 Ratio approx. Twistane ) G48 Refs. 

The pyrolysis experiments with the twistanes 257 and 266 reflect the relative stabilities of twistanes and isotwistanes, the latter being strongly favored. 

An interesting reaction is the addition of water to the twistane 302. The obtained product, exclusively 10 -hydroxy-2-thia-7-aza-isotwistane 278), proved the expectation to be correct that sulfur will predominate over nitrogen in neighboring group participation. Furthermore, experiments with D2SO4 in D2O allowed a dif- 

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Starting Material 2,7-Dihetero-isotwistanes and -twistanes as Well as... 

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