... The Diels-Alder-Reaction with inverse-Electron-Demand, a very efficient versatile Click-Reaction Concept for proper Ligation of variable molecular Partners Manfred Wiessler1, Waldemar Waldeck2, ... solutions. Ligation methods A series of qualified reactions were compiled by Sharpless in its concept for the Click-Chemistry [2] dealing with consistently and rapidly running chemi-cal ligation...