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Formation of Nucleophilic Carbenes from Heterocyclic N-Methyl Betaines.

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Formation of Nucleophilic Carbenes from
Heterocyclic N-Methyl Betaines
intimately connected with the formation of a low-energy
limiting structure (2").
Received: May 28th, 1965
[Z lOOOj82S IE]
German version: Angew. Chem. 77,680 (1965)
By Dr. H. Quast and E. Frankenfeld
Chemisches lnstitut der Universitat Wiirzburg (Germany)
We have found that the betaines ( I u ) , ( I v ) , and(1w) withthe
heterocycles A = 2-pyridine [I], 2-quinollne [2], or I-isoquinoline [3] are decarboxylated by merely warming t o
40-80 "C in an aprotic solvent. The ylides (2) formed 141 can
be trapped by N-electrophiles (3) t o form the colored compounds (4).
I
- C 0 2 60-809:
X-N'
I
X-Nl@
(3)
Proportion Yield 1x1in N-methyipyrrolidone of (4) from
(3) : ( I )
( l a ) at 8 0 ° C ( I b ) at 6 0 ° C
( I c ) at 60'C
I
1
[ I ] E. M . Kosower and J. W. Patton, J . org. Chemistry 26, 1318
(1961).
[2] W. H . Mills and F. M . Hanzer, J. chem. SOC.(London) IZI,
2011 (1921).
[3] Prepared by methods similar to those described in [2,3].
141 Nucleophilic carbenes or ylides analogous to (2') have already
been detected by trapping reactions in the benzthiazole (R = CH3,
CZHS),pyridine, quinoline, and isoquinoline series (R = H). See
H. Quast and S. Hunig, Angew. Chem. 76, 989 (1964); Angew.
Chem. internat. Edit. 3, 800 (1964); Chem. Ber., in press; H .
Balli, Angew. Chem. 76, 995 (1964); Angew. Chem. internat.
Edit. 3, 809 (1964); B. R. Brown, Quart. Revs. (Chem. SOC.London) 5 , 131 (1951).
[S] S. Hiinig and H . Nother, Liebigs Ann. Chem. 628, 69 (1959).
[6] W. H. Mills and R. S . Wisharf,J. chem. SOC.(London) 117,
587 (1920).
[7] P . Haake and J . Mantecon, J. Amer. chem. SOC.86, 5230
(1964).
Reaction of Ally1 Halides with Diazomethane
Catalysed by Copper Salts
55-60 IS]
2:l
By Prof. Di. W. Kirmse and Dip].-Chem. M. Kapps
56
Chemisches lnstitut der Universitlt Marburg/Lahn
(Germany)
Substituents X in compounds (3) and (41 :
O-+N-
CH30
(0)
(CH3)2N43-
ib)
Catalytic decomposition of diazomethane by copper salts i n
the presence of olefins [ I ] or aromatic compounds [2] causes
insertion of methylene to give cyclopropane or cycloheptatriene derivatives. When this reaction was applied to ally1
halides ( I ) , two products were obtained, vir. cyclopropylmethyl halides (2) and 4-halogenobutenes ( 3 ) ; the total yield
based on diazomethane was between 20 and 6004.
6H3
7
CH2=C-CH2X
+
CHzNz
= H, cH3,
X = C1, B r
(1)
I:H3
The rate-determining step in the reaction is apparently the
decarboxylation, for the rate of liberation of CO:! is not
affected by the nature of the electrophile (3) although the
yields of ( 4 ) depend in a characteristic fashion on the reactivity of the trapping reagent.
The betaines ( I x ) , ( l y ) , and ( I z ) with the heterocycles A
4-pyridine [I], 4-quinoline [ 6 ] , and 3-isoquinoiine [31 decompose some 50-100°C higher than ( l u ) , (Iv), or ( I w ) .
They d o not form dyes ( 4 ) with (3a) and (3b) under the
conditions mentioned above. The greater stability of (lx) is
in accordance with the results of kinetic experiments [71
where it was found that the rates of decarboxylation of 2-, 3-,
and 4-pyridine betaines a t 196OC in ethylene glycol containing 5 % quinoline were in ratios of 1600:2.8: I . In order to
explain these findings it is assumed that the stabilization of
(2) is due t o an inductive effect of the nitrogen and the mutual
steric hindrance of the carboxyl and methyl groups in the
ground state of ( 1 ) [7]. However, comparison of ( I v ) and
(Iw) with ( l z ) reveals that the stability of thc ylide (2) and
hence the activation energy for the decarboxylation are
Angew. Chem. internat. Edit. Vol. 4(1965)
No. 8
When X = CI, the main product is (2), but when X = Rr,
preferentially (3) is produced. The formation of (3) i n
preference to (2) is also promoted when R =- CI. Numerous
anhydrous salts of copper(1) and copper(I1) can be used as
catalysts in this reaction. The use of Cu(1) halides precludes
exchange with the halogen of the ally1 halide.
The formation of (2) is in accordance with known examples
[ I ] and occurs stereospecifically [.?I. The 4-halogenobutenss
(3) are not formed by rearrangement of (2), nor by insertion
of H2C into the C-X bond as in the photolysis of diazomethane in the presence of alkyl halides [4]. It was shown
with deuterated and methyl-substituted compounds that the
formation of (3) is accompanied by a complete ally1 rearrange-
P
R'CH=C-CHzX
69 1
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