REACTION OF AMINOCARBENE COMPLEXES OF CHROMIUM WITH ALKYNES .5. INFLUENCE OF THE RING SIZE ON THE PRODUCT DISTRIBUTION - FORMATION OF PYRROLES FROM PYRROLIDINE AND ITS DERIVATIVE-SUBSTITUTED CARBENE COMPLEXES
A. Parlier et al., REACTION OF AMINOCARBENE COMPLEXES OF CHROMIUM WITH ALKYNES .5. INFLUENCE OF THE RING SIZE ON THE PRODUCT DISTRIBUTION - FORMATION OF PYRROLES FROM PYRROLIDINE AND ITS DERIVATIVE-SUBSTITUTED CARBENE COMPLEXES, Organometallics, 14(6), 1995, pp. 2760-2774
A series of aminocarbene complexes of chromium derived from piperidine
(1), hexa- and heptamethyleneimine (4) and (8), pyrrolidine (13a-d, R
(1) = Me, H, Ph, thienyl), perhydroindole (21), thiazolidine (24a,b, R
(1) = Me, Ph), pyrroline (30a,b), and azetidine (33a-e and 36) have be
en synthesized and subjected to alkyne insertion reactions. Aminocarbe
ne complex 24a-E has been fully characterized by X-ray structure analy
sis. Crystal data for 24a-E: C10H9O5NSCr, monoclinic, space group P2(1
)/n, a = 8.3011(9) Angstrom, b = 11.949(1) Angstrom, c = 13.101(2) Ang
strom, beta = 95.74(1)degrees, V = 1293(1) Angstrom(3), d(calcd) = 1.4
1 g cm(-3), Z = 4. Whereas complex 1 reacted with diphenylacetylene to
give first the ylide complex 2, the thermolysis of which led to the b
ridgehead lactam 3, complexes 4, and 8 gave directly the expected brid
gehead lactams 6 and 11. The structure of 3 has been determined by X-r
ay diffraction. Crystal data for 3: C27H25ON, monoclinic, space group
P2(1)/c, a = 10.080(4) Angstrom, b = 11.727(3) Angstrom, c 18.014(6) A
ngstrom, beta = 102.40(3)degrees, V = 2080(14) Angstrom(3), d(calcd) =
1.21 g cm(-3), Z = 4. In contrast to 1, 4, and 8, all of the new carb
ene complexes derived from five-membered cycloamines except 24b gave p
yrrole derivatives as the result of the alkyne/CO insertion followed b
y migration of an alkyl chain from nitrogen to the carbon atom of the
inserted carbonyl group and loss of its oxygen atom. The structures of
14a, the Cr(CO)(3) complex of 15a, and 22 could be unambiguously esta
blished by X-ray crystallography. Crystal data for 15: C24H21O3NCr, tr
iclinic, space group P1, a = 6.918(1) Angstrom, b = 10.057(1) Angstrom
, c = 15.193(2) Angstrom, alpha = 72.410(9)degrees, beta = 84.99(1)deg
rees, gamma = 84.66(3)degrees, V = 1001(3) Angstrom(3), d(calcd) = 1.4
0 g cm(-3), Z = 2. For 22: C24H25N, monoclinic, space group P2(1)/n, a
= 11.119(3) Angstrom, b = 10.682(2) Angstrom, c = 15.428(3) Angstrom,
beta = 102.23(2)degrees, V = 1791(7) Angstrom(3), d(calcd) = 1.21 g c
m(-3), Z = 4. Besides these pyrroles, the expected bridgehead lactams
17a-d were isolated from 13a-d together with the lactone complex 18 in
the case of 13b. Crystal data for 18: C19H12O5Cr, orthorhombic, space
group Pc2(1)/b, a = 10.356(1) Angstrom, b = 12.366(5) Angstrom, c = 1
2.529(2) Angstrom, V = 1604.4(8) Angstrom(3), d(calcd) = 1.54 g cm(-3)
, Z = 4. However, 24b gave as the major insertion product the aminofur
an 26, and pyrroline-derived carbene complexes 30a,b gave lactams 32a,
b and trace amounts of pyrroles 31a,b. Only trace amounts of pyrroles
were detected starting from carbene complexes derived from azetidine (
33a-e) and 36, which gave mainly the lactams 35a,d and 37. Mechanisms
for these new transformations of aminocarbene complexes of chromium ba
sed on the behavior of the Stevens-type acyl-stabilized N-ylides will
be suggested.