Reaktive E = C(p—p)π‐Systeme, XXXI Erste Vertreter aminosubstituierter 1,2,4‐Diazaphosphole

Reactive E = C(p—p)π Systems, XXXII [1] . — First Representatives of Amino‐Substituted 1,2,4‐Diazaphospholes (Diisopropylamino)phosphaethyne i Pr 2 N—C≡P reacts at 20° C in a [3 + 2] cycloaddition with (trifluoromethyl)diazomethane ( 2a ) or methyl diazoacetate ( 2b ) to yield a mixture of the corresponding regioisomers 1 H ‐1,2,4‐diazaphospholes ( 5a or 5b ) and 1 H ‐1,2,3‐diazaphospholes ( 6a or 6b ) in quantitative yields (isomer ratio: 5a/6a = 2:1; 5b/6b = 4:1). X‐ray diffraction studies on 5a and 5b indicate a delicate charge balance in the bonding system of 1 H ‐1,2,4,σ 2 ‐diazaphospholes under the influence of the exocyclic push/pull substituents i Pr 2 N and CF 3 or CO 2 Me, respectively.