Chemistry Reference
In-Depth Information
Tab. 4.50.
Reaction of various substrates with phosphines and one-third of an equivalent of
triphosgene [988].
Substrate
Product
Yield
(isolated)%
H
2
O
Ph
3
PO
100 (a)
Cl
O
Cl
75 (a)
OMe
OMe
75 (a, b)
NHCHO
NC
(o-TolylNH)
2
CO
o-Tolyl
a
N
b
C
b
N
a
o-Tolyl
73 (a, b)
OMe
OMe
88 (a, b)
NH
2
N=PPh
3
CHO
CHCl
2
80 (a)
95 (c)
MeO
MeO
CHO
CHCl
2
50 (a)
O
2
N
O
2
N
CONH
2
CN
78 (a, b)
72 (b, c)
(a) Phosphine
¼
Ph
3
P; (b) Et
3
N also present; (c) Phosphine
¼
Ph
2
P
attached to cross-linked polystyrene.
(HMPT) has been investigated [1314]. A structural study of the electrophilic inter-
mediates obtained from carboxamides and chlorinated Lewis acids was extended to
the phosphoric amides. The action of phosgene and POCl
3
on hexamethylphos-
phoric triamide (HMPT) can lead to a chlorophosphonium salt (Me
2
N)
3
PCl
þ
Cl
,
the structure of which has been proved by NMR (
1
H,
13
C,
31
P,
15
N). The mecha-
nism of its formation is comparable to that for formation of the chloroiminium
chloride (Vilsmeier reagent) from the corresponding amide. The action of chlo-
rine on HMPT does not lead to a stable salt of the same kind, but essentially to
the substitution product Me
2
NP(O)ClNMe
2
. A new biphosphorylated compound
(Me
2
N)
2
P(O)OPCl(NMe
2
)
3
was identified when an excess of chlorine was reacted
with HMPT.
The Vilsmeier reagent prepared by treating DMF with COCl
2
is a useful reagent
in nucleic acid chemistry, e.g. for chlorination and formylation of nucleosides, and
in the synthesis of oligonucleotides [1315].
