A two-step four-component queuing cascade involving a Heck coupling, π-allylpalladium trapping and Diels–Alder reaction
Palladium-catalyzed cross-coupling of bicyclopropylidene ( 1 ) with iodoethene ( 11 ) in the presence of a secondary amine 12 provides allylidenecyclopropanes 13 which undergo immediate Diels–Alder reactions upon addition of dienophiles 14– 18 to provide 8-(1′-aminoethyl)-substituted spiro[2.5]oct-7...
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Published in | Tetrahedron Vol. 61; no. 48; pp. 11355 - 11373 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
OXFORD
Elsevier Ltd
28.11.2005
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | Palladium-catalyzed cross-coupling of bicyclopropylidene (
1
) with iodoethene (
11
) in the presence of a secondary amine
12
provides allylidenecyclopropanes
13
which undergo immediate Diels–Alder reactions upon addition of dienophiles
14–
18
to provide 8-(1′-aminoethyl)-substituted spiro[2.5]oct-7-ene derivatives
23a–
26a
in 29–66% yield. The same one-pot, two-step queuing cascade can be carried out with other iodoalkenes including cyclic ones and with cyclic dienophiles such as
N-arylmaleinamides
19–
22
and
N-phenyl-triazolinedione
37
to furnish highly substituted spiro[2.5]oct-4-enes and spirocyclopropanated heterobicycles
47a–
49a
,
41a–
46a
(17–50%). Spirocyclopropanated heterobicycles such as
55
,
56
(25 and 38% yield, respectively) can also be obtained by an inter-intra-intra-intermolecular version of this queuing cascade involving 1-hydroxyethyl- and 1-aminoethyl-substituted iodoethenes
53
,
54
.
Graphical Abstract |
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ISSN: | 0040-4020 1464-5416 |
DOI: | 10.1016/j.tet.2005.09.014 |