Synthesis and phosphorylating properties of 2‐chloro‐2,3‐dihydro‐3‐(methylsulfonyl)‐1,3,2‐benzoxazaphosphole 2‐oxide. Derivatives with chloro substituents on the benzene ring

The synthesis and the use of the five-membered cyclic phosphorylating agents 1a–c are described. Their difunctional phosphorylating properties towards alkanols and hydroxylated amino acids and the cleavage reaction of the formed phosphoric acid triesters to diesters with oximate or platinum/hydrogen are investigated and compared to the “parent” compound 2-chloro-2,3-dihydro-3-(methylsulfonyl)-1,3,2-benzoxazaphosphole 2-oxide. Dichlorobenzoxazaphosphole 1b is the most reactive of these reagents with respect to phosphorylation with ring opening and oximate cleavage of the phosphoric acid triesters, followed by o-chlorobenzoxazaphosphole 1a, the unsubstituted phosphole I, and p-chlorobenzoxazaphosphole Ic.