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Stereocontrolled Synthesis of Angularly Fused Tricyclic Ring Systems by Means of 1‐Metalla‐1,3,5‐hexatrienes (M=Cr, W)
Author(s) -
Wu HePing,
Aumann Rudolf,
Fröhlich Roland,
Wibbeling Birgit
Publication year - 2002
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20020215)8:4<910::aid-chem910>3.0.co;2-t
Subject(s) - chemistry , cyclopentane , ring (chemistry) , carbene , tricyclic , stereochemistry , triple bond , isomerization , medicinal chemistry , double bond , polymer chemistry , organic chemistry , catalysis
An efficient pathway for the stereocontrolled synthesis of functionalized, angularly fused tricyclic ring systems from readily available (1‐alkynyl)carbene complexes [(OC) 5 M=C(OEt)C≡CR] (M=Cr, W; R=Ph, c‐ C 6 H 9 ) is described. The synthesis involves the formation of a 1‐metalla‐1,3,5‐hexatriene from the (1‐alkynyl)carbene tungsten complex [(OC) 5 W=C(OEt)C≡C‐ c‐ C 6 H 9 ] and a secondary amine, and its thermally induced π‐cyclization to a tetrahydroindene, which undergoes a spontaneous isomerization to another tetrahydroindene. Condensation of these tetrahydroindenes with pyran‐2‐ylidene complexes derived from (1‐alkynyl)carbene complexes [(OC) 5 M=C(OEt)C≡CPh] (M=Cr, W) proceeds smoothly giving angularly fused tricyclic ring systems, rearrangement of which may generate spiro(cyclopentane‐1,1‐indanes) as side products. The synthesis is highly versatile and can be applied to the formation of various ring systems, such as steroid‐type ring skeletons.