... Tetrahedron. Volume 50, Issue 4, 24 January 1994, Pages 1261–1274. ... Tetrahedron, 30 (1974), pp. 4013–4020 and references therein. ... 13; A practically reverse regiochemical result was previously reported 14 for the reaction of 4 with dimethylamine: 5:6 (R=Me) ratio= 33:67. ...