ISSN:
0009-2940
Keywords:
Alkynylcarbene complexes of chromium and tungsten
;
(β1-Aminovinyl)carbene complexes of chromium and tungsten
;
4-Amino-1-metalla-1,3-dienes
;
(3-Aminoalkenyl)carbene complexes
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Organic Syntheses via Transition Metal Complexes, 63[1]. - (β1-Aminovinyl)carbene complexes and (Alkinyl)aminocarbene Complexes of Chromium and Tungsten. - Stereochemistry and Isomerization(Alkinyl)alkoxycarbene complexes LnM=C(OEt)-C≡CR 3 [LnM=Cr(CO)5, W(CO)5; R=Ph, nBu, SiMe3] react with primary amines H2NR1 4 (R1=Me, iPr, allyl, CH2Ph, CHMePh) to give (β1-aminovinyl)carbene complexes LnM=C(OEt)-CH=CR-NHR1 (Z)-5 (by a Michael-type 3-addition) together with (alkinyl)aminocarbene complexes anti-6 (by a 1-aminolysis). The product ratio (Z)-5/anti-6 is strongly influenced by the reaction temperature: at 20°C (Z)-5 is obtained as the main product, while at -78°C mainly anti-6 is formed. Both reactions are stereospecifical; they yield 5 in the (Z), and 6 in the anti configuration only. An anti/syn isomerization is achieved by acidic treatment of anti-6i. The (alkinyl)aminocarbene complex 6a adds EtOH/EtO- albeit much slower than the (alkinyl)alkoxycarbene complex 3a. A NH21-Enamino carbene complexes (CO)5Cr=C(OEt)-CH=C(NH2)Ph [(Z)-8a] is obtained on addition of ammonia to 3a at 90°C.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19931260220
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