Kondensation von Methylcarben‐Komplexen mit Säureamiden: β‐Alkoxyalkenyl‐ und β‐Aminoalkenylcarben‐Komplexe von Chrom und Wolfram ‐ Konkurrenz von Kondensation und Insertion

Organic Syntheses via Transition Metal Complexes, 44 1 . ‐ Condensation of Methyl Carbene Complexes with Acid Amides: β‐Alkoxyalkenyl‐ and β‐Aminoalkenyl Carbene Complexes of Chromium and Tungsten ‐ Competition of Condensation and Insertion The condensation of the methyl(ethoxycarbene) complexes L n M = C(OEt)CH 3 ( 4 ) [L n M = Cr(CO) 5 , W(CO) 5 ] with acid amides RCONR 1 R 2 (5) under the influence of POCl 3 /Et 3 N leads stereoselectively to ( E )‐β‐aminoalkenyl(ethoxycarbene) complexes L n M=C(OEt)CH=C(R)NR 1 R 2 [( E )‐6] (R = H, aryl, alkyl). A condensation of 4 can also be achieved via amidium salts 11 , which are easily available from 5 . In this case, ( E )‐6 and ( E )‐β‐alkoxyalkenyl(ethoxycarbene) complexes L n M=C(OEt)CH = C(R)OEt[( E )‐13] were obtained. Via the cyclic amidium salts 15 and 20 four‐to seven‐membered lactams ( E )‐ 17 and ( E )‐ 21a‐d are accessible. The reaction of 4 with acid amides RCH 2 CONR 1 R 2 (2) and POCl 3 /Et 3 N yields mainly insertion products L n M=C(NR 1 R 2 )C(R)=C(OEt)CH 3 [( E )/( Z )‐ 22 ] and only small amounts of condensation products L n M=C(OEt)CH=C(CH 2 R)NR 1 R 2 [( E )‐ 23 ].