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New Cleavage Reactions of Methylenediamine Derivatives and -Dialkylamino Ethers.

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New Cleavage Reactions of Methylenediamine
Derivatives and x-Dialkylamino Ethers
H. Biihme, MarburgjLahn (Germany)
a-Halogenated amines are formed by cleavage of aminals
with acid halides. Analogously, N,N,N',N'-tetraalkylmethylenediamines react with sulfonic anhydrides t o yield dialkylmethyleneimonium sulfonates and dialkylsulfonamides.
Tetraethyl pyrophosphate reacts with aminals or a-dialkylamino ethers to produce carbimonium salts of diethylphosphoric acid and phosphoric ester amide or triester. The
carbimonium salts of diethylphosphorous acid, formed from
tetraethyl pyrophosphite, undergo a Michaelis-Arbusow rearrangement, whereby dialkylaminomethylphosphonic esters
can be isolated.
If mixed anhydrides are used for the cleavage reaction, the
imonium salt of the stronger acid present in the anhydride is
formed, together with the amide or ester of the weaker acid.
N - C H 2- N,
R, N-R3
E N = C H T @OR2+ R3-O-R1
R2, R3
R - C O - , R-SOz-, R-SO-, ( R 0 ) 2 P O - , ( R 0 ) z P -
On the other hand, the reactions of acetyl nitrate with aminals
yield dialkylnitramines and acetoxymethyldialkylamines
which are also obtainable by cleavage of aminals with
carboxylic anhydrides. When the reaction is carried out
using the mixed anhydride of acetic and formic acids, the
primary product ar-formyloxymethyldialkylamine is decarboxylated even at -20 "C and methyldialkylamine is formed.
Carbimonium halides which are usually considered to be
a-halogenated amines, on heating or on recrystallization
from aprotic polar solvents, yield dimers and trimers which
are also formed in the reaction of methylenediamine derivatives with methylene halides. Contrary to the monomers, the
dimers and trimers d o not possess the band of the C = N
double bond in the infrared spectrum at 5.95 p.
to theory, to be most pronounced for phosphorus. This is
the case particularly if the phosphorus carries a positive
charge. Three models were discussed for phosphonium salts
containing one to four p-dimethylaminophenyl groups, and
for phosphine oxides, phosphine sulfides, and phosphines
with one to three p-dimethylaminophenyl groups:
1. No participation of phosphorus d-orbitals.
2. Participation of a phosphorus d-orbital, with conjugation
across the phosphorus atom.
3. Participation of a phosphorus d-orbital, the phosphorus
atom inhibiting conjugation.
The ultraviolet absorption of all compounds investigated
could not be explained on the basis of models 1 and 2 or of
a model which had previously been suggested by other
authors [I]. On the other hand, all predictions based o n the
third model were found to be verified in the ultraviolet and
infrared spectra. An acceptor effect of phosphorus was
found experimentally which is greater than that of a CN
group in the salts, and which is nearly equal to C N in the
phosphines, oxides and sulfides. Increase of the electron
density at the phosphorus atom (replacement of C6H5 by
CH3; solvation of the phosphonium group; comparison of
the phosphines, oxides, and sulfides with onium salts) lessens
the acceptor effect. As borne out by the infrared spectra of
the oxides and sulfides, the same holds for the px-d, character of the P=O and P = S bonds: the frequency and intensity of
the PO- and PS-valence vibrations decrease (as would be expected according to model 3) with an increase of the donor
effect acting on the phosphorus.
The acceptor effect is not unambiguously discernible in compounds with unsubstituted phenyl groups; however, the small
participation of the phosphorus 3 p-orbital in the aromatic
z-bond systems of triphenylphosphine may be caused by a
counteraction of 3 p- and 3 d-orbital participation. As strong
electron donors demonstrated the participation of 3 dorbitals, it seemed possible that 3p-orbital participation
would be detected after introduction of strong acceptor
substituents. This was in fact the case, as indicated by the
properties of the phosphines (C~H~)ZP-C&-A@), where
A = N02, CN, CHO, COOCH3, COOH, CON(CH3)2, or
February 25th, 19651
[VB 917/216 IE]
German version: Angew. Chem. 77, 593 (1965)
Cyclopropane and Cyclobutane Derivatives by
Rearrangement of Unsaturated Compounds
M. Hunuck, Tubingen (Germany)
[GDCh-Ortsverband Sud-Wurttemberg,
Tubingen (Germany), February 19th, 19651 [VB 916/218 IE]
German version: Angew. Chem. 77, 594 (1965)
The Bond Character in Aromatic Phosphorus
Compounds - a Contribution to the Problem of
the Existence and Properties of p,-d, Bonds
G . P. Schiemenz, Kiel (Germany)
The participation of vacant d-orbitals of the valence electron
shell of hetero-atoms of the fifth main group in aromatic
x-bonding systems (p,-d,
bond) can be expected, according
Angew. Chem. internnt. Edit.
V d . 4(1965) [ No. 7
Open-chain homoallyl compounds are isomerized smoothly
to cyclopropylmethyl compounds, but yields are lower in the
case of cyclic homoallyl compounds. Here, the primarily
formed homoallyl cations are partly stabilized by hydride
shift. Thus, cyclohexen-4-yl tosylate is isomerized to an
extent of only 10 76 during acetolysis to yield the stereoisomeric bicyclo[3.1 .O]hex-2-yl acetates. On hydrolysis, cyclopenten-4-yl sulfonates yield 40 % cyclopenten-4-01 and 60 7;
cyclopenten-3-01. Similarly, the reaction of 4-bromocyclopentene with AgzO in water, proceeding by an SN1-mechanism, does not result in a bicyclic compound. The reduction
of cyclopenten-4-yl sulfonate with LiAIH4, on the other
hand, yields 4 % bicyclopentane, together with other hydrocarbons.
On hydrolysis, 2-(cyclohexen-l-yl)ethyl sulfonates ( l a ) isornerize, as does 2-(cyclohexen-l-yl)ethylamine ( I b ) during
deamination with nitrous acid, to form spiro[2.5]octan-4-ol
(2) and bicyclo[4.2.0]octan-1-ol(3) ;both alcohols can thus be
obtained in high yield.
[l] H . Goetz, Angew. Chem. 75, 675 (1963); Angew. Chem.
internat. Edit. 2, 552, (1963).
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cleavage, methylenediamine, reaction, ethers, dialkylamino, new, derivatives
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