... Please enable JavaScript to use all the features on this page. Tetrahedron Letters. Volume 50, Issue 29, 22 July 2009, Pages 4199–4200. Cover image Cover image. NCS with thiourea as highly efficient catalysts for acetalization of aldehydes. ... 7, 45 min, 97 a. 8, R Ph, 2.5 h, 50 b. ...