Chemistry Reference
In-Depth Information
norbornene, a catalytic reaction of phenylacetylene quantitatively proceeded without
NaBH
4
.
Co(acac)
2
(1-5 mol%)
O
R
NaBH
4
(10-20 mol%)
R
+
CH
2
Cl
2
, 80-100 °C
CO (40 atm)
R = Ph: quant.
R = n-C
6
H
13
: quant.
R = cyclohex-1-enyl: 80%
R = (CH
2
)
3
Cl: 83%
R = CH
2
OH: 69%
R = CO
2
Et: 33%
Scheme 3.17
In the above two reports, the intermolecular reaction of alkyne with norbornadiene
or norbornene was mainly stated, but the intramolecular reaction of 1,6-enynes with an
unsubstituted alkyne terminus also proceeded.
Livinghouse considered that impurities in Co
2
(CO)
8
would induce the formation of
oligomers as an inactive complex, and paid attention to the pure grade of Co
2
(CO)
8
.
He prepared highly pure Co
2
(CO)
8
by recrystallization using HPLC grade hexane or
sublimation at room temperature under reduced pressure (50 mmHg), and submitted it to
the reaction. In his first report,
18
a pure Co
2
(CO)
8
-catalyzed reaction was achieved by aid
of photo-irradiation at 50-55
◦
C (Scheme 3.18).
R
1
R
1
Pure Co
2
(CO)
8
(5 mol%)
DME, 50-55 °C, CO (1 atm)
R
2
Z
Z
O
()
n
R
2
Photo-irradiation by Q-beam
®
Z = C(CO
2
Et)
2
, R
1
= H, R
2
= H (n = 1): 95%
Z = C(CO
2
Et)
2
, R
1
= H, R
2
= H (n = 2): 74%
Z = C(CO
2
Et)
2
, R
1
= H, R
2
= Me (n = 1): 91%
Z = NTs, R
1
= H, R
2
= H (n = 1): 81%
Z = NTs, R
1
= Ph, R
2
= H (n = 1): 75%
Z = C(CH
2
OMe)
2
, R
1
= CH
2
OH, R
2
= H (n = 1): 80%
Scheme 3.18
In the following report,
19
he realized the catalytic reaction by the strict control of the reac-
tion temperature (60
◦
C) without the aid of photo-irradiation (Scheme 3.19). The stereospe-
cific transformation of an enyne with
Z
-olefinic moiety to the corresponding cycloadduct
could also be possible.
