Organische Synthesen mit Übergangsmetall‐Komplexen, 64 [1] . 1,4‐Diaminonaphthaline über Ketenimin‐Komplexe aus (β‐Aminovinylcarben)chrom‐Komplexen und Isocyaniden

Organic Syntheses via Transition Metal Complexes, 64 [1] . – 1,4‐Diaminonaphthalines via Ketenimine Complexes from (β‐Aminovinylcarbene)chromium Complexes and Isocyanides The thermal reaction of (dienylcarbene)chromium complexes (= 1‐chroma‐1,3,5‐trienes) with isocyanides provides a mild and regiospecific access to aromatic amines. Thus, 1,4‐diamino‐2‐ethoxynaphthalines 6a–d [1‐NH c ‐C 6 H 11 ; 4‐NRR 1 = NMe 2 ( a ) ( S )‐2‐hydroxymethylpyrrolidinyl ( b ) (1 R ,2 S )‐2‐methylamino‐1‐phenyl‐1‐propanol ( c ), N t BuMe ( d )] are obtained by the cyclization of ( E )‐(β‐aminostyrylcarbene)chromium complexes (CO) 5 Cr=C(OEt)CHC(NRR 1 )C 6 H 5 [( E )‐ 3a–d ] with cyclohexyl isocyanide ( 4 ) at 90°C in 72–85%. The aminocarbene complexes ( E )‐ 3a–d are accessible with high stereoselectivity [>95% ( E ) configuration] and chemical yields of 91–96% by the addition of secondary amines HNRR 1 2a–d to the (1‐alkoxy‐3‐phenylpropynylidene)chromium complex (CO) 5 Cr=C(OEt)C≡CC 6 H 5 ( 1 ). 3 and 4 give initially mono‐ and bis(isocyanide) complexes, e.g. ( E )‐ 8a and ( E )‐ 9a , and subsequently dienylketenimine complexes by the insertion of 4 into the MC bond of 3 . Dienylketenimine complexes are key intermediates in the formation of 6 .