Non-destructive Cleavage of N-Acylsultams Under Neutral Conditions: Preparation of Enantiomerically, Pure Fmoc-Protected α-Amino Acids

Heating diastereoisomerically pure N‐acylsultams 3 or 4 with allyl alcohol/Ti(OR)4 efficiently yields sultams 1 or 2 and allyl esters 5. Esters 5 are hydrolyzed under nonbasic conditions in the presence of Wilkinson's catalyst to give enantiomerically and diastereoisomerically pure carboxylic acids 7. A series of [(fluoren‐9‐yl)methoxy]‐carbonyl‐(Fmoc)‐protected amino acids 14 were thus prepared from N‐[N'‐(Fmoc)amino]acylsultams 12.