text:  <unk> <unk> are known to <unk> unactivated hydrocarbons with remarkable regio , and <unk> . This is a highly coveted transformation , and similar reactivity and specificity is seldom rivaled , especially considering the nonmetallic nature of the oxidant . <unk> <unk> show high selectivity toward tertiary hydrogens . <unk> of primary carbons and <unk> of a compound with two <unk> sites have never been observed . Retention of stereochemistry is very high , often 95 - 98 % . ( <unk> of stereochemistry may be further enhanced by the addition of a fluoride salt ) . 
  