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(a)
I
I
Pd(QPhos)
2
(5 mol%)
PhMe, 100
O
H
°
C, 16 h
O
7.60
68% yield
>20:1 dr
7.59
I
(b)
Pd(QPhos)
2
(5 mol%)
KI (2 equiv)
Ph
Br
N
N
PhMe, 100
°
C, 16 h
O
Ph
O
7.62
89% yield
3:1 dr
7.61
Scheme 7.31 Domino carboiodination with (a) aryl iodides and (b) bromides.
Adapted from Ref. 101. Copyright 2011 American Chemical Society.
I
(a)
I
Pd(P
t
Bu
3
)
2
(5 mol%)
NEt
3
(1 equiv)
PhMe, 110 °C
R
O
O
R
7.62
7.63
up to 94% yield
up to >99:1 dr
cis
:
trans
(b)
I
R
1
I
Pd(P
t
Bu
3
)
2
(5 mol%)
NEt
3
(1 equiv)
PhMe, 110 °C
R
1
R
2
O
O
R
2
N
N
7.64
7.65
up to 96% yield
down to <1:9 9 dr
cis
:
trans
Scheme 7.32 Diastereoselective Pd(0)-catalyzed synthesis of (a) isochromans and (b)
chromans.
Adapted from Ref. 102. Copyright 2012 American Chemical Society.
isochromans 7.63 (Scheme 7.32a) and chromans 7.65 from precursors 7.62 and
7.64, respectively (Scheme 7.32b).
102
Despite many reports of their individual
syntheses,
103-106
general approaches to both frameworks are rare.
107
Hence the
developmentofawidelyapplicable,concise catalytic method was warranted.
The observed diastereoselectivities were attributed to be the result of
minimization of A
1,2
strain (Figure 7.3a) and axial-axial
interactions
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