174759-83-2Relevant academic research and scientific papers
Organic syntheses via transition metal complexes. 83.1 cis-1-metalla-1,3,5-hexatrienes (butadienylcarbene complexes) of tungsten via ring opening of pyranylidene complexes
Aumann, Rudolf,Roths, Klaus,Jasper, Beate,Fr?hlich, Roland
, p. 1257 - 1264 (2008/10/08)
Aminolysis of the 2H-pyran-2-ylidenetungsten complex 3 affords amino-1-tungsta-1,3,5-hexatrienes with different structures, depending on the reaction temperature and the type of amine involved. Addition of primary amines RNH2 (4a-d) (R = allyl, n-Bu, CH2Ph, i-Pr) to 3 at -15 °C yields salt-type (3Z)-6-amino-1-tungsta-1,3,5-hexatrienes 5a-d by reversible ring opening of the pyranylidene ring. Addition of 4a-c at 20 °C affords (3Z)-2-amino-1-tungsta-1,3,5-hexatrienes 6a-c by an irreversible ring opening of the pyranylidene ring. Secondary amines RR1NH 8a-c [RR1N = Me2N, 2-(hydroxymethyl)pyrrolidine, pyrrolidine] undergo an irreversible ring opening to 2-amino-1-tungsta-1,3,5-hexatrienes 9a-c. Aminolysis of 3 in the presence of Me3SiCl/Et3N affords acetimino pyranylidene complexes 10, from which (3Z)-2,6-diamino-1-tungsta-1,3,5-hexatrienes 11 are derived upon aminolysis. Thermolysis of 6a in THF/pyridine affords the captodative 1-amino-1,3-hexadien-5-one 12. 2H-Pyran-2-ylidene complex 3, C19H12O7W, was characterized by X-ray diffraction.
