close

Вход

Забыли?

вход по аккаунту

?

Isomeric Peroxy Esters of Sugar Carboxylic Acids.

код для вставкиСкачать
[I] This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie.
[Z] Ch. Riichardt, H. Bock, and I. Ruthardt, Angew. Chem. 78,
268 (1966); Angew. Chem. internat. Edit. 5, 253 (1966).
[3] A similar ring closure reaction was recently described by
M. Schu1z: Angew. Chem. 79, 940 (1967); Angew. Chem. internat. Edit. 6,950 (1967).
14) Neighboring group participation of a-acyloxy groups in
esterifications was observed also independently by A. R. Mattocks, J. chem. SOC.(London) 1964, 1918, 4840. See also E. E.
Bfurse, Bull. SOC.chim. France (4) 1914, 725.
151 These investigations were stimulated by H. Schulz’s results
in the sugar series [3]; we thank Frau I. Mayer-Ruthardt for
carrying out the experiments.
0
Rase
Pyridine
2,6-Lutidinz
Pyridine
No n e
Pyridine
2.6-Lutidine
Pyridine
Pyridine
Pyridine
NaOH/H20
Pyridine
2,6-Lutidine
No n e
[a] Given as % of ( 3 ) i n the mixture of (2) ,
usually greater than 60%.
0
100
20
100
100 Ibl
100
80
70
40
100
72
100 [cl
100
(3) ; total ! Ids were
Isomeric Peroxy Esters of Sugar Carboxylic Acids
By Manfred Sclrulz and P . Brrlin[*l
Reaction of penta-U-acetyl-D-gluconoyl chloride ( I ) with
t-butyl hydroperoxide gives two isomeric peroxy esters. In
the presence of bases such as 2,4,6-collidine, pyridine, or
triethylamine in benzene at room temperature, t-butyl
2,3,4,5,6-penta-O-acetyi-~-peroxygiuconate
(2) is formed in
80 % yield. M.p. 70-72”C, [a]’,’ = +6.53’ (c = 3.5 in
CHC13), IR band of the perester-carbonyl at 1779 cm-1.
[bl Same result with t-pentyl hydroperoxide.
[c] Same result with aqueous sodium hydroxide as base.
I
If in ( I ) neither R1 nor R* is hydrogen, then ring closure is
favored by increase in size of R1 and R*, by a smaller group
R3, and by a bulky base ( e g . 2,6-lutidine or triethylamine).
The ring closure is kinetically controlled. ( I ) , R1 = R3 =
CH3, R*= C2H5, and ( I ) , R1= R2 = CH3, R3 = S - C G H ~ - C H ~ .
in absence of a base, give (3) almost exclusively.
Acid chlorides (/) in which Rl or R2 is hydrogen, even with
the bulky base ethyldiisopropylamine, afford only a little (3).
On the other hand, even in the absence of base, U-acetyllactoy1 chloride ( I ) , R1 = H, R2 = R3 = CH3, and U-acetylglycoloyl chloride ( I ) , R * = R2 = H, R3 = CH3, give (3)
almost exclusively [5J.
The composition and the active-oxygen content of the oily
peroxides were determined. The dioxolane derivatives (3)
can be quantitatively and qualitatively analysed by means
of the carbonyl bands near 1800 cm-1 [(2), C = O at 1735 and
1775 cm-11 and the N M R signal of the methyl group R3 at
T = 8.33 [(2), R3 = CH3, 7 = 7.961.
Experimenfd: 4.11 g (25.0 mmole) of a-acetoxyisobutyryl
chloride in 15 ml of petrol ether (b.p. 4OoC) or methylene
chloride was added dropwise over 15 min to a stirred solution
of 3.22 g (30.0 mmole) of 2,6-lutidine and 3.60 g (40.0mmole)
of 1-butyl hydroperoxide in 45 ml of the same solvenl at 0 ‘C.
After having been stirred for two hours the solution was
filtered and subsequently washed neutral with dilute sulfuric
acid, aqueous sodium bicarbonate, and water and dried over
magnesium sulfate. It was quickly chromatographed on a
1Ocm column of neutral Alz03 (activity I) in order to
remove residual hydroperoxide and was then concentrated in
vacuum. 3.31 g (60 %) of colorless, oily 2,5,5-trimethyl-2-tbutylperoxy-l,3-dioxolan-4-one(3 R I = R ~ = R ~ = C Hwas
~)
isolated having nz = 1.4189 and containing 7.2% active
oxy&n (calc. 7.3%); I R spectrum showed C = O band at
1808 cm-1; molecular weight (osmometric) = 243 (calc. 232).
The same material was obtained when no base was present
and the HCl formed was removed in a stream of nitrogen.
Received: May 19th and August ISth, 1967 [Z 600aIEI
German version: Angew. Chem. 79, 939 (1967)
HC-OAc
I
(2)
R
I
R =
HC-OAC
I
HC - O A c
I
C H2-OA c
However, in the absence of a base, reaction of the acid
chloride ( I ) with t-butyl hydroperoxide gives exclusively the
isomeric “anomalous perester” (3) (11. 2-t-Butylperoxy-2methyl-5-(~-~rabino-1,2,3,4-tetracetoxybutyl)-l,3-dioxolan4-one ( 3 ) is isolated in 90 % yield after ( I ) has been heated
with an excess of t-butyl hydroperoxide at ca. 70 OC for 4 h;
it has m.p. 162-163OC and [ci]’,’ = -8.0” (c = 3.7 in
CHCl3). Ring closure to the 1,3-dioxolanone system, which
occurs here under acid conditions, is caused by neighboring
group participation of the a-acetyl group of ( I ) [21.
The structure of (3) was proved by elemental analysis, 1R
spectrum (acetyl-carbonyl 1747 cm-1, dioxolanone-carbonyl
1813 cm-I), and N M R data (t-butyl protons, T = 8.77;
acetyl-CH3 protons, T = 7.94; CH3 protons of the methyl
group on the dioxolanone ring, T = 8.30).
Reaction of tetra-U-acetylmucoyl dichloride with t-butyl
hydroperoxide in the presence of pyridine gives the bisperoxy ester (4), m.p. 126OC (decomp.), in 91 72 yield.
Warming the acid chloride with an excess of t-butyl hydro0%,O-O-C(C
0
‘\
C
‘c -(>
HC-OAc
I
AcO-$H
H$.
0 CH3
AcO-qH
I
,O- 0 -C ( CH3) 3
AcO-dH
I
HC - 0 A c
[*I Priv.-Doz. Dr. Ch. Riichardt and Dip1.-Chem. G. Hamprecht
Institut fur Organische Chemie der Universitat
Karlstr. 23
8 Munchen 2 (Germany)
950
Angew. Chem. inremat. Edit. / Vol. 6 (1967) J No. I /
peroxide without a base gives exclusively (S), m.p. 211 to
213 "C (90 % yield).
Treatment of (2) or (3) with methanolic 0.01 N NaOCH3
solution causes a sugar degradation by a new type of perester degradation. The anomalous peroxy ester (3) is completely decomposed within 5 h at room temperature, yielding
70 % of D-arabinose (crystalline, paper-chromatographically
pure), 66 P: of carbon dioxide, t-butyl alcohol, and methyl
acetate, with 30 % of methyl o-gluconate as by-product
(percentages calculated with respect t o compound (3)). Complete decomposition of the normal peroxy ester (2) requires
more energetic conditions: after 8 hours' warming at 60 'C,
D-arabinose was isolated in 51 % yield.
H
The diperoxy compounds (4) and (5) are not degraded with
C-C cleavage by sodium methoxide solution; only transesterification and deacetylation occur, yielding dimethyl
mucate (90 %).
We interpret the decomposition of (3) as fragmentation [31
of a n intermediate pyranoid compound (6). Presumably, (2)
also decomposes by way of a cyclic intermediate.
Reaction of (2)
I
with ( l a )
with (Ib)
Reaction
time (min)
Received May 19th and August 18th. 1967
[ Z 600b 1E)
German version: Angew. Chem. 7Y, 940 f1967
.~
1
3
7
10.5
18
23
62
1440
95
90
80
75
65
54
30
27
Po I
-
10
20
2s
36
46
70
73
24
63
1440
20
23
27
90
85
80
77
73
[*I Dr. Manfred Schulz and Dip].-Chem. P. Berlin
Institut fur Organische Chemie der Deutschen Akademie
der Wissenschaften zu Berlin
An der Rudower Chaussee
DDR 1199 Berlin-Adlershof (Germany)
111 An analogous synthesis of 5,s-disubstituted 2-t-butylperoxy1,3-dioxola1i-4-ones was recently discovered independently by
Ch. Riichardt and G. Hatnprechr, Angew. Chem. 79, 939 (1967);
Angew. Chern. internat. Edit. 6, 949 (1967).
[2] For neighboring group participation of cr-acetoxy groups in
esterifications compare A. R. Mnrtocks, J. chern. SOC.(London)
1964, 1918, 4840.
[31 For fragmentations of other types of sugar peroxides compare M . Schulz, H.-F. Boedeiz, and P. Berlin, Liebigs Ann. Chem.
703, 190 (1967); M . Schulz and L. Somogyi, Angew. Chem. 79,
145 (1967); Antew. Chem. internat. Edit. 6, 168 (1967).
Stereochemistry of the Cycloaddition of Sulfonyl
Isocyanates and N-Sulfinylsulfonamides to Enol
Ethers 1'1
By F. Efenbrrger and G. Kiefrrl*J
4-Alkoxyazetidin-2-ones (3) are formed on cyclaaddition of
sulfonyl isocyanates to enol ethers under mild conditions [*I.
We have now studied the stereochemistry of this reaction in
order to decide between a synchronous mechanism, as
proposed by Huisgen et al. [3J for the cycloaddition of
ketenes t o enol ethers, and a two-stage reaction involving
an intermediate compound of type ( 4 ) .
The proportions of the $-lactams (30) and (3h) formed (see
table) can be obtained from the newly appearing resonance
signals of the proton HA in (3u) o r (3h) with a n accuracy of
about :4 %. (3u): HA gives a doublet at T = 4.5, JAB5.3
Hz; (3h): HA gives a doublet at T = 4.81, JAB = 2 Hz. The
structures (30) and (3b) are assigned on the basis of the
coupling constants JAB[41.
From the table it can be seen that (fu) reacts stereospecifically with (2) and that (Ib) reacts stereoselectively, but that
after somewhat more than an hour an equilibrium mixture
containing 27 % of (30) and 73 % of (36) is formed from
- (36)
either pure ( I n ) or pure ( I h ) . The isomerization (30) %
is formulated as occurring by way of a resonance-stabilized
polar intermediate ( 4 ) .
When kept for several days in DCCI3 the equilibrium mixture
of (3u) and (3h) rearranges to the thermodynamically more
stable compound (5), the compound (4) being again assumed
as intermediate.
Enol ethers combine with N-sulfinylsulfonamides to give 1,2thiazetidine 1-oxides (7) 151. N M R spectroscopic studies
conducted during this cycloaddition in DCCI3 show a stereospecific reaction of both ( l a ) and (Ib). The products (7.)
and (76) do not isomerize and do not rearrange o n long
storage in DCCI,.
The cis- and trans-1-butenyl ethyl ethers ( l a ) and ( I b ) ,
which are separable by preparative gas chromatography,
were treated separately in DCC13 with p-tosyl isocyanate (2)
in the molar proportions 1 :1, and the progress of the reaction
was followed by N M R spectroscopy (Table).
One minute after the reactants had been mixed the signals of
( I n ) (HA = doublet at T =: 4.1 8, H B = quadruplet at T = S.74;
JAB= 6.3 Hz) and ( I b ) (HA = doublet at 7 = 3.82, H B = 2
triplets at T = 5.32; JAB= 12.6 Hz) had disappeared, whence
it is concluded that there is very rapid reaction with (2).
Angew. Chem. internat. Edit.
/ Vol. 6 (1967) 1 No. I1
The results show that in the reaction of enol ethers with polar
reagents the kinetically controlled cycloaddition occurs
largely synchronously. Quite possibly, different bond lengths
are to be considered for the transition state I6l. Depending o n
the ring strain, isomerization and removal of a proton occur,
95 1
Документ
Категория
Без категории
Просмотров
1
Размер файла
224 Кб
Теги
acid, esters, carboxylic, sugar, isomeric, peroxyl
1/--страниц
Пожаловаться на содержимое документа