Water, acyl addition with alkynes

Sulfonyl azides participate in unique CuAAC reactions with terminal alkynes. Depending on the conditions and reagents, products other than the expected triazole 20 [118] can be obtained, as shown in Scheme 7.9. For example, N-sulfonyl azides are converted to N-sulfonyl amidines 21 when the reaction is conducted in the presence of amines [119]. In the aqueous conditions, N-acyl sulfonamides 22 are the major products [120,121]. In addition to amines and water, the latter can be trapped with imines, furnishing N-sulfonyl azetidinimines 23 [122]. 

The following reaction of an alkyne with an Ir complex looks like the C-C triple bond cleavage (Eq. 27) [41]. It is not the direct C-C triple bond cleavage by the reaction with metals. The first step of this reaction is addition of water to the triple bond forming an aldehyde. Elimination of CO from the resulting acyl complex gives the product. 

---