ORGANIC SYNTHESES VIA TRANSITION-METAL COMPLEXES .64. 1,4-DIAMINONAPHTHALINES VIA KETENIMINE COMPLEXES FROM (BETA-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-NHc-C6H11; 4-NRR1=NMe2 (a) (S)-2-hydroxymethylpyrrolidinyl (b) (1R,2S)-2-methylamino-1-phenyl-1-propanol (c), NtBuMe (d)] are obtained by the cyclization of (E)-(beta-aminostyrylcarbene)chromium complexes (CO)5Cr=C(OEt)CH=C(NRR1)C6H5 [(E)-3a-d] with cyclohexyl isocyanide (4) at 90-degrees-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 HNRR1 2a-d to the (1-alkoxy-3-phenylpropynylidene)chromium complex (CO)5Cr=C(OEt) C=-CC6H5 (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 M=C bond of 3. Dienylketenimine complexes are key intermediates in the formation of 6.