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Nucleophile-dependent regioselectivities in the nucleophilic reaction of (S)-4-benzyl-2-fluoroalkyl-1,3-oxazoline to different types of fluorinated compounds were investigated experimentally and theoretically. The ring opening of (S)-4-benzyl-2-bromodifluoromethyl-1,3-oxazoline by arenethiolates exclusively occurred at the C5 position of the 1,3-oxazoline ring, whereas completely different regioselectivity was observed for a unimolecular radical nucleophilic substitution (S(RN)1) at the terminal bromine atom of the CF2Br group when arenolates were employed as the nucleophiles. The reaction of (S)-4-benzyl-2-trifluoromethyl-1,3-oxazoline with nucleophiles such as arenethiols, arenols, and TMSCl underwent nucleophilic ring opening in a regiospecific way, while the use of TMSCF3 was determined to proceed through nucleophilic addition to the C═N bond.

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Title compounds (III) can be easily prepared under the conditions shown.

Study on the Tandem Synthesis of Optically Active 2-Substituted 4 (or 5)-Phenyl--1,3-oxazolines. -The proposed mechanism for this reaction involves an aziridine intermediate with the acidities of the carboxylic acids playing a key role in the selective formation of various intermediates. While the halogenated acetic acid derivatives (V) can be employed in this reaction, acetic acid itself does not yield the desired product. -(JIANG*, H.; LU, W.; CAI, Y.; WAN, W.; WU, S.; ZHU, S.; HAO, J.; Tetrahedron 69 (2013) 9, 2150-2156, http://dx.