An example is Boc.The term ???arylcarbonyl??? as used herein refers to the group ???COR wherein R is an aryl group as defined above.The term ???sulfonyl??? as used herein refers to the group ???SO2???.The term ???arylsulfonyl??? as used herein refers to the group ???SO2R wherein R is an aryl group as defined above.The term ???hydroxyalkyl??? as used herein refers to the group ???ROH wherein R is a