Chemistry Reference
In-Depth Information
The commercially available HOCH
2
C(CH
2
Br)
3
was initially alkylated via the
Williamson synthesis, then converted (NaSH/S/DMF, Cu/C
6
H
5
Me, Zn/HCl/C
6
H
6
)to
form the MeOCH
2
C(CH
2
SH)
3
and lastly treated with HC(OMe)
3
to generate the 4-
methyloxymethyl-2,6,7-trithiabicyclo[2.2.2]octane, MeOCH
2
C(CH
2
S)
3
CH [59].
Pentaerythritol with 3.1 equiv. of acrylonitrile in the presence of base and then
using Fischer esterification conditions generated HOCH
2
C(CH
2
OCH
2
CH
2
CO
2
Me)
3
,
which can be O-protected, then reduced to the triol ROCH
2
C(CH
2
OCH
2
CH
2
-
CH
2
OH)
3
[65,66]. Conversely, pentaerythritol was initially monoprotected with
tert-butylchlorodiphenylsilane (Z
¼
TBDPS) then transformed into a family of very
useful 1
3 branched monomers, for example, ZO
2
CHC(CH
2
OH)
3
, ZO
2
CHC-
(CH
2
OCH
2
CH
!
CH
2
)
3
, ZOCHC(CH
2
OCH
2
CH
2
OH)
3
, ZOCH
2
C(CH
2
OCH
2
CH
2
N
3
)
3
,
HOCH
2
C(CH
2
OCH
2
CH
2
N
3
)
3
,CH
2
¼
¼
CHCH
2
OCH
2
C(CH
2
OCH
2
CH
2
NH
2
)
3
,CH
2
¼
CHCH
2
OCH
2
C(CH
2
N
3
)
3
,andHO
2
C(CH
2
)
6
OCH
2
C(CH
2
N
3
)
3
by a series of simple
conversions [67]. TheTBDMSOC
2
HC(CH
2
OH)
3
was transformed toTBDMSOC
2
HC-
(CH
2
OCH
2
C
CH)
3
upon treatment (NaH/THF; 82%) with HC
CCH
2
Br [68].
The commercially available pentaerythritol
triallyl ether, HOCH
2
C(CH
2
OCH
2
CH
CH
2
)
3
, was benzylated (NaH/DMF) with 4-bromobenzyl bromide to give
(91%) BrC
6
H
4
CH
2
OCH
2
C(CH
2
OCH
2
CH
¼
CH
2
)
3
, which was hydroborated (9-
BBN, NaOH/H
2
O
2
; 78%) affording BrC
6
H
4
CH
2
OCH
2
C[CH
2
O(CH
2
)
3
OH]
3
, then
transformed (HC
¼
CC(OH)Me
2
/(dppf)PdCl
2
/CuI/pyrrolidine; 81%,
then NaOH/
C
6
H
5
Me; 79%) to HC
CC
6
H
4
CH
2
OCH
2
C[CH
2
O(CH
2
)
3
OH]
3
[69]. Pentaerythritol
triallyl ether can be prepared by treatment of pentaerythritol with allyl bromide
(NaOH) in 50% yield and subsequently converted (I
2
/PPh
3
/imidazole) to ICH
2
C-
(CH
2
OCH
2
CH
¼
CH
2
)
3
[70,71]; whereas
Jones oxidation of HOCH
2
C(CH
2
-
OCH
2
CH
CH
2
)
3
formed the desired focal acid group, which was treated
SOCl
2
, followed by ethylenediamine to give H
2
NCH
2
CH
2
NHOCCH
2
C(CH
2
-
OCH
2
CH
¼
¼
CH
2
)
3
[72].
