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Faclie Regeneration of Carbonyl Compounds from 1 3-Dithiane 1-Oxides via 1-Ethoxy-1 3-dithianium Salts.

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Facile Regeneration of Carbonyl Compounds from
1,SDithiane 1-Oxides via l-Ethoxy-l,3-dithianium
Salts[**]
Table 2. Some l-ethoxy-1,3-dithianium tetrafluoroborate salts 131 and -2.4.6trinitrobenzenesulfonates ( 3 ' ) . All compounds gave correct C. H, N \slues.
The rearrangement of ( l e i into (3c.J. R = C , , H , - O C H , - p I d 1 0 an insufficiently purc product.
- -
By Ingjried Stuhl. Jiirgeii Ape], Ruirzrr Munske, and Jurgen
Gosseld ['I
Carbonyl compounds can be protected as 1,3-dithiane 1oxides ( I ) ; they are usually released again in an acid
medium"]. We have found that ( I ) can be alkylated regioaelectively at the 0-atom with triethyloxonium tetrafluoroborate
(2).even at 0°C (CH2C12,argon), to give the hitherto unknown
l-ethoxy-l,3-dithianium tetrafluoroborates ( 3 ) ,which are isolable in high yields.
-
-
-~
~
R
.-
~.
[";,I
- - -
-
~.
.~-
~-
~
-~
~~
M.p. ["C]
(dec.)
Yield
~-
~~
'H-NMR,
ii-values [a]
-
-
-,
~~
~
~~
(3a)
13
80
115
(3a')
H
75
145
fib')
CH3
67
103
4 . 6 4 ~(CD.,),CO
;
4.90. 4.62d. ' J = - I2 132;
4 4 8 q ; CD3CN
4.90. 5 . 0 5 ~ ;4.49. 4.46q:
75
80
75
47
92
77 -80
i n 1 --lo4
101
75 -78
CD3CN
5.20, 5 0 5 ~ 4.50:
;
CD~CI~
6.05s: 3.87q: CD2CI2
5 9 7 s ; 3.85q; C D ~ C N
6 z s ; 3 . 9 ~ 4(cI),)~co
;
6.00s: 3 . 8 5 ~ :C D I C N
( 3 ~ ' ) C(CHd3
13111 ChHs
(3rl'j C6H5
( i f ' ) Ct,H1-NO2-(p)
(.;g 1
ChHd -C'lH.3-(p)
.~
~
--
~- ~-
52
-
~
~~
-
5.16. 4.96d. ' J = - I 2 Hz:
-
-
[n]Thesign:ilsaIegicen in [he order S-CH;-S"
~
~
~~
~~
or S~ C H --S ': O - - C H L
161.
Evidence for the regioselective ethylation at the 0-atom
of ( 1 ) is provided, inter a h , by the quantitative nucleophilic
cleavage of the S-0 bond of ( 3 u ) with NaOD in the NMR
experiment. S-alkoxysulfonium salts behave analogously[71.
The salts (3) rapidly cleave in aqueous neutral medium
at 5"C, giving the carbonyl compounds ( 4 ) and propylene
disulfide ( 5 ) in high yields (over 60%). The observed separation
of ( 5 ) , which was also isolated in the acid hydrolysis of
( I )[21,confirmsthe postulated reaction mechanism ria hydroxydithianium ions.
This hydrolytic variant for the cleavage of 1,3-dithiane 1oxides ( 1 ) riu 0-ethyl derivatives (3) constitutes a novel
and preparatively simple method.
As precursors for the preparation of ( 3 ) we used the trun.s-2substituted sulfoxides ( I ) (Table I ) (content of trails isomer
>90 ?,j. which we synthesized from the 1,3-dithiane~[~]
by
monooxidation with NaIO4['I.
BF?
+
NaOD
+
C2HQD + NaBF4
( I ti)"].
OC2H5
rJ%
I
D s , 0 C 2 H 5
0
Table I . Some nen I,.i-dithiane I-oxides ( I j [a].
€3 F p
T-
i3n2i
BF p
~-~
~
R
~
-~
~
I I P ~C
~
Yield
['',;I
H
O C~H ~ - ( ~ ) 90
( I f 1 CAHJ- NO2-(p)
( l y 1 C h H l C'H3-(p)
~
n
S,S=O
We carried out a "C-NMR analysis on the parent compound ( 3 u ) . The signals of the ring-C-atoms were assigned
on the basis of selective 'H-13C decoupling, those of the
ethyl-C-atoms were locatable under off-resonance conditions
[I3C-NMR (CD3CN): 6= 75.1 (OCHlj; 46.7 (C-6); 45.8 (C-2);
29.0 (C-5); 27.2 (C-4); 15.5 (CH3)]. The sequence of the ring-Catom signals corresponds to that of the starting sulfoxide
13ai)
~.
-+
trans.
ci.5
M.p.
['C]
"C-NMR,
ii-values [b]
9 2 : ~ 166
83
91.9
94
92:X
6x.x.29.?.i1.2,
54.4. 55.0 ( 0 C H 2 )
176 -177 6X.6.29.1.310.517
165
6X.X,29.0.3O.X.
52.2. 20 7 (C'H,)
~-
[a] ( l u i . R - H ; i l b l , R = C H , : ( I ( J, R = C ( C H 3 I I : I I d j . R = C h H S 'ire
known. [h] "C-NMR of the trrrns-compounds (23 MHr, CDCI3, TMS=O):
thc signals arc xiven in t h e sequence C-2, C-4. C-5. C-6 [5].
The tetrafluoroborates (3) were characterized as 2,4,6-trinitrobenzenesulfonates ( 3 ' ) (Table 2).
-
['I, J. Apel, Dip1.-Chem. R. Manske
Bereich ()r@aiiischcChemie der Universitgt,'Gesamthochschule
fleinricti-l'lett-Str. 10. D-3500 Kassel (Germany)
[ -1 Author 11, w h o m correspondence should be addressed.
This work was supported by the Fonds der Chemischen Industric.
We thank I>r. S. Brryrr (C'niversitit Marburg) for help with the experiment?
o n the selectivc decoupling and low-temperature ' H - N M R measurements
and Prof Dr. I / . LrirLiier (Uiiiversitlt Giittingen) for recording thc 100 M H r
' H - N M R spectra. Thanks are also due to Pror. Dr. If. Kessler (Universitht
Frankfurt, Main) for valuable discussions regarding the temperature-depcndent ' H - N M R spectra.
[*] Prof. Dr. .I. Gosselck. Dr. 1. Stahl
A low-temperature 'H-NMR experiment [in (CD3),CO;
T up to - 106"C] provided n o evidence of a conformational
process in the sense of the equilibration (3ul ) * ( 3 ~ 2 ) . The
splitting of the A-resonance of the AB doublet of the C-2
protons ( J 2 & = 2.5 Hz) at lower field strength, the size of
= 12 H ~ ) [ ~ ] ] , the
a n dseparathe geminal couplingconstant (2J,,ZH
tion of Hbe and H h d by cu. 0.4 ppm in the 'H-NMR spectrum
(100MHzj indicate almost exclusive participation of the conformer ( 3 ~ ~ ) .
Conformationally fixed forms are also present in the salts
f 3 h ) - ( 3 g ) ; ( 3 h ) and ( 3 c ) contain small proportions of
cis isomers.
A novel intramolecular decomposition has been observed
in the case of ( 3 d ) . In anhydrous dichloromethane at room
temperature it cleaves quantitatively within about 1 h into
benzaldehyde ( 4 d ) and 1 -ethyl-l,2-dithiolanium tetrafluoroborate (6).
[**I
The salt (6) was isolated as the 2,4,6-trinitrobenzenesuIfonate (6') (dec. pt 153-1 54°C) ['H-NMR (CDICN)of (6')
165
7 0 1 00 0
1.41 (t, 3H), 2.74 (t of t, 2H), 3.32 (4, 2H), 3.75 (t, 2H),
3.99 (t, 2H), assignment by proton decoupling]. The spectral
pattern corresponds to that of 1,2-dithiolane 1,l -dioxide['!
General Procedure
Synthesis of (3): (1) (6 to 8 mmol) is dissolved in anhydrous
CH2Cl2in the absence of moisture and the solution treated
with 2 g of molecular sieve (4& MERCK). An equimolar
amount of (2) in lOml of anhydrous CHzC12 is then added
at 0°C and the mixture stirred for up to 3 h under argon.
The salt (3) is precipitated with anhydrous ether, the solution
decanted off, and the crude product (3) dried over P4OID
at 0.1 torr/25"C. The salts (3') are first obtained by addition
of a concentrated ethanolic solution of picrylsulfonic acid
to the crude (3) and then reprecipitated from acetonitrile/ether
or CH2Clr/ether.
Regeneration of ( 4 ) : The dried crude tetrafluoroborate
(3) is treated with water (5°C).After a few minutes the precipitate of ( 5 ) is removed by filtration and the aldehyde worked-up
or precipitated as the 2,4-dinitrophenylhydrazone derivative.
opened, while the newly formed five-membered ring remains
intact, i . e. bond switch is observed at n-hypervalent sulfur.
We report here on a simple and typical example of bond
switch. When 3,4-disubstituted 5-imino-A2-l,2,4-thiadiazoline
( I )I3' is heated with excess imidate at 60-80°C without
solvents, ethanol is eliminated and the 1 : 1 adduct (3) of ( I )
and the nitrile R3-CN is obtained in good yields (in Table 1).
Table 1. Some 1,2,4-thiadiazole ( 3 ) . ('H-NMR data: 6 values, CDC13, Me&
int. [4]).
R'
Received. November 13, 1978 [ Z 148 IE]
German version: Angew. Chem 91, 179 (1979)
CAS Registry numbers:
( l a ) , 16487-10-8: ( I b ) , 60349-75-9; ( I c ) , 41893-04-3; (l<1),.60349-76-0;
( l e ) , 69278-13-3; (1j). 69278-14-4: ( l y ) . 69278-15-5; ( 2 ) , 368-39-8: ( 3 ~ ) .
69278-17-7; ( 3 U ' ) , 69278-18-8: (3h'), 69278-20-2; ( 3 ~ ' ) 69292-14-4:
,
(3d),
69278-22-4: f 3 d ' ) , 69278-23-5: ( 3 f ' ) , 69278-25-7; (39'). 69278-27-9;
( 4 d ) . 100-52-7; ( 5 ) , 42557-04-0: ( 6 ) - 69275-29-1 ; i6'), 69278-30-4
[I]
[2]
[3]
141
151
161
[7]
181
[9]
Review of hydrolysis methods: 8.-7:
Gr6hel. D. Seebach, Synthesis 1977,
357.
R. Ktrltn, F . A . Neugehuuer, Chem. Ber. 94, 2629 (1961).
Review: D. Srehurh, Synthesis 1969. 17.
Review of oxidations with NaIOl: A . J. Faliudi. Synthesis 1974, 229.
F. A . Cure!, 0 . D. Duiiey. Jr., W C. Hurton, J. Org. Chem. 43. 96
(I978).
I . Sfuhl,Dissertation, UniversitBt GieBen 1973.
Review: J . P . Murino in: Topics in Sulfur Chemistry. Vol. 1. Thieme,
Stuttgart 1976, p. 68.
J. B. Lumbert, S . I . Feutherman. Chem. Rev. 75, 611 (1975).
L. field, R. 8.Burbee. J. Org. Chem. 34, 316 (1969).
Bond Switch with Participation of K-Bonded S" in
Thiathiophthene-AnalogousSystems[**]
By Kin-ja Akiba, Shin-ichi Arai, Tolzru Tsuchiya, Yohsuke Yamarnoto, and Fujiko Iwusaki"]
In the thiathiophthenes, a class of stable x-hypervalent molecules, the S-S bonds are influenced by substitution or introduction of heteroatoms into the ring"'. Both iminothiadiazolines['"] and iminooxadiazolinesL2b1react with activated acetylenes with cycloaddition-elimination;the elimination is probably due to the great difference in electronic nature of the
two five-membered rings of the intermediate n-h4-sulfurane.
In all these reactions, the original S-heteroatom bond is
U
h
c
d
R2
R3
Me
Me
hl e
2.3hfO.03 [a] 3.6910.13 2 5410.03
Me
Mc
Ph
7.2 -7.6 (m. 3 H)
8.0- 8.4 (m, 2H)
El
Me
Me
Ph
Me
Me
7.48 k0.02
M.p.
["CI
Yield
139.2 -140.2
66
152.2 -183.7
80
149.2~-150.2
174.1- 175.1
77
48
[ X,]
[a] Coupling with N H (6=9.5. J = 1.5 Hz).
The structure of the adduct (3) was deduced by comparison
of its NMR spectral data with those of related compound^'^].
The IR spectra contain characteristic absorptions at 3250
(v= NH) and 1630-1640cm-'
(VC=NH)[~"].
We also synthesized (3 a), (3 c ) and (3 d ) V I U an independent
route by heating the nitriles R'-CN
with the thiadiazole
(4)15] to SO-100°C in the presence of AIC13; the yield of
(3) was about 20%['].
Finally, the structure of ( 3 a ) was determined by an X-ray
structure analysis on a single crystal. The molecule is almost
planar (dihedral angle between the "rings": 274.7"); the N."S
and N-S bond lengths are 2.500 and 1.668A, respectively,
thus confirming intramolecular N... S interaction.
Me
[A]
Fig. 1 . Bond lengths
and angles ["I in compound ( 3 n ) (Details. F .
Iwaaki. K . ilkiba, unpublished).
[*] Prof. Dr. K. Akiba. DipLChem. S. Arai, Y. Yamamoto. Dr. T. Tsuchiya
Department of Chemistry, Faculty of Science, The University of Tokyo
Hongo. Tokyo 113 (Japan)
[**I
Prof. Dr. F. Iwasaki
Department of Materials Science, The University of Electro-CommunicatlOIlS
Chofu-shi. Tokyo 182 (Japan)
This work was supported in part by the Itoh Science Foundation.
166
Surprisingly, the salt formation of the bases ( 3 ) proceeds
ria bond switching. Thus the tetrafluoroborates of (3 a ) and
( 3 c ) have the structures ( 7 a ) and ( 7 c ) , respectively, derived
as shown below by long range coupling with the NH proton
(the position is marked by an asterisk). This is supported
by the finding that the protons of the three analogous methyl
,4uyru. Chem. Int. Ed. Enyi 18 ( 1 9 7 9 ) N o . 2
0 Verlag
Cheniir. G m h H , D-6940 Weiniieim. 1979
0570-01133 7 Y m O 2 - O l 6 6 9; 01 .00.'0
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salt, oxide, carbonyl, compounds, ethoxy, dithian, faclie, regenerative, dithianium, via
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