Cyclic sulphoxides conformation

Bis(4-hydroxyphenyl) sulphoxides butadienyl - see Butadienyl sulphoxides carbamoyl - see Carbamoyl sulphoxides chiral - see Chiral sulphoxides complexes of 567-573 conformational analysis of 84-89 cyclic - see Cyclic sulphoxides cyclopentanone - see Cyclopentanone sulphoxides... 

Thus 5-(2-propynyl)-L-cysteine 5 5 -dioxide ring-closes in dilute ammonium hydroxide solution to the ammonium salt of (72), which on the basis of n.m.r. data appears to exist in a half-chair conformation. Under more controlled conditions, (-f-)-5-(2-propynyl)-L-cysteine iS-oxide behaves similarly, giving the corresponding cyclic sulphoxide, but the cyclization of the (-)-isomer was unsuccessful. 

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