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Exceedingly Mild Desulfurization of Thiols by Sodium Triethylhydroborate and Transition Metal Chlorides.

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The methylthio group of (8) was easily displaced by nucleophiles and gave, for example, the 5-amino and 5-hydrazino derivatives, m.p. 165 and 159 "C, respectively. It appears
that this new heterocycle, the substitution of which can be so
easily modified, could provide many interesting new compounds as candidate drugs.
The transfer of the methylene group from nitrogen to sulfur in the reaction (2) + (4) is contrary to the usual direction
of isomerism (e. g. thiocyanates -+ isothiocyanates). The
same unusual shift furnished the (non-basic) by-product (7).
That this transfer may occur at the dithiocarbamate stage (2)
is indicated by a change in the 'H-NMR spectrum when water i s added to the cold mixture of the diamine ( l ) ,carbon
disulfide, ammonia, and methanol. The initial spectrum of
the N-alkyl dithiocarbamate (2) changes to that of the S-alkyl dithiocarbamate (5) (see Table 1).
Table 1. 'H-NMR data of intermediates (2) and (5) and products (41 and (81. 6
values, in (CD,),SO [a].
(21, 8.30' ( 1 H, NH), 7.22 (5H. Ph), 5.85. (2H, NHZ), 5.35 (ZH, CHzPh), 4.58
(ZH, d**, CHzNH coupled with NH
Procedure
(4) [and (7)]:The diamine (1)13](1.0 g, 0.005 mol), pyridine
(20 ml), CS2 (3.8 g, 10 equiv.), and triethylamine (1.0 g, 2
equiv.) are heated in a bath at 115 "C for 6 h. The mixture is
taken to dryness in uacuo at 90"C, and the residue shaken
with 1N KOH (12.5 ml). Filtration from the sulfide (7) [m.p.
173°C (from 50% aqueous ethanol); MS, m/e=406 (M')]
and acidification of the filtrate to pH 3.5 gives (4) in 60%
yield, crystals from 50% aqueous ethanol [m. p. about 190 "C
with effervescence. MS: m/e= 262 (M +)I.
(8): Compound (4) (0.131 g), I N NaOH (0.6 ml), and
CH31(0.085 g, 1.2 equiv.) are stirred for 15 min at 20°C. After filtration, a 91% yield of (8) is obtained 1m.p. 127°C
(from cyclohexane)].
Received: September 10. 1979 [Z 432 IE]
German version: Angew. Chem. 92, 319 (1980)
[I] M . Busch, J. Prakt. Chem. 51 121, 257 (1895); W L. F. Armarego: Quinazolines. Wiley-Interscience, New York 1967. p. 276.
[2] A. Dunand, to be published.
131 A . Albert, J. Chem. SOC.Perkin Trans. I 1973, 1634.
(41, 7 19 (m, SH, Ph), 5.60 (2H, CHzPh), 425 (ZH, CHzS)
(5). 7.99. (2H, SC NH,), 7.22 (5H. Ph), 5.77' (2H, 4-NHz). 5.27 (2H, CHIPh),
4.00 ( 2 H, s. CH,S)
f8), 7.31 (5H. Ph). 5.72 (2H, CHzPh), 4.40 (2H, CHzS), 2.58 (3H, Me)
[a] *: vanishes on addition of DZO:**: d becomes s on addition of DZO.-For
comparison. the CHzS signal in the sulfide (7) is 6=3.63.
Exceedingly Mild Desulfurization of Thiols by
Sodium Triethylhydroborate and Transition Metal
Chlorides[**]
By Howard Alper and Trish L. Prince"'
The S-methyl derivative (8) of the thione forms triclinic
crystals (Pi, a=8.742, b=9.717, c=9.823
a=110.09",
p= 113.70", y = 102.17", Z=2). The molecular configuration
was determined by conventional crystal structure analysis
(diffractometer data''', R = 5.1%) (see Fig. 1).
A,
Fig. 1. Crystal structure of 3-benzyl-3,7-dihydro-5-methylthio-1,2,3-triazolo[4,5dJ[l,3]thiazine (8) 121.
Desulfurization reactions are of considerable current interest, particularly with reference to their possible application
to the removal of sulfur from fuel oil, coke, and other energy
sources. One of us has recently begun a search for new desulfurization processes[']. We now wish to report a simple and
exceedingly mild method for the desulfurization of thiols.
Mixed hydride/transition metal halide reagents have come
into increased use in recent years'''. Treatment of 2-naphthalenethiol (la) with anhydrous ferrous chloride and sodium triethylhydroborate [molar ratio 1:2 :41 in tetrahydrofuran at - 78 "C gives naphthalene (2a) in 81-85% yield,
2,2'-Binaphthyl (3a) appears as a reaction by-product if
CoC12is used instead of FeCI,. VC13 gave less fruitful results.
Table 1 lists examples.
Table 1. Desulfurization of thiols ( I ) to hydrocarbons (2) and didehydrodimers
(3) with Na[(C2H,),BH]/MC1..
The 1,2,3-triazole ring is completely planar. The thiazine
ring has a half-boat like conformation with the torsional an= 2.6(5)O and
gles C(S)---N(4>-C(S)-S(6)
S(6)-- C(7)--C(8)-C(9)
= - 30.4(5)"; C(7) and N(4) lie
slightly above and below the triazole plane, respectively.
While the C(sp3)-S bonds are only marginally different,
C(7)-S(6) (1.798(5) A) and C(11)-S(l0) (1.7811(7) A), the
two C(sp2)-S
bonds differ significantly by having
C(5)- S(6) (1.779(4) A) larger than C(5)-S(l0) (1.733(4) A)
in relation with more N-C-S-C
torsion around
C(5)- S(6) ( - 24.6(4)") than around C(5)-S(10) ( - 8.2(4)").
The methyl hydrogen atoms' observed locations are consistent with a staggered configuration around the S(lO)-C(ll)
bond. The benzyl substituent also has an energetically favored configuration, the C( 12)-C(pheny1) bond being almost
perpendicular to the triazole ring, and the N(3)-C( 12) bond
is only 10" out of perpendicular to the benzene ring.
Angew. Chem. Int. Ed. Engi. 19 (1980) No. 4
R=
MCI,
Yield
(2)
a
b
C
d
e
2-Naphthyl
2,s-Dichlorobenzene
4-Methoxybenzyl
Triphenylmethyl
1-Dcdecyl
FeCl2
coc12
VCI,
coc12
FeCI,
FeCI2
FeCIZ
8 1-85
72
23
84
63
59
78
[%I
[a]
13)
27
8
[a] Isolated yields. Products identified by comparison of analytical and spectral
data with those of authentic materials.
['I
Prof. Dr. H. Alper, T. L. Prince
Department of Chemistry, University of Ottawa
Ottawa, Canada KIN 984
["I We are indebted to the Natural Sciences and Engineering Research Council
for support of this research.
0 Veriag Chemie, CmbH, 6940 Weinheim, 1980
0570-0833/80/0404-03t5
$02.50/0
315
311-314 Anzeige
This desulfurization reaction not only occurs with aromatic thiols, but with benzylic and nonaromatic thiols as well.
Yields are good and product isolation is simple.
General procedure
The thiol ( I ) (1.5 mmol) in THF (2-3 ml) is added to anhydrous metal chloride (3.0 mmol) in THF (2 ml). After addition of THF (8 ml), the reaction mixture is stirred at room
temperature for 15-25 min, cooled to - 78 "C, and then a
1 M solution of Na[(C2H5),BH]in THF (6.0-6.2 ml) is added by syringe. The solution is stirred for 15-20 min at
- 78 "C, and then allowed to warm to room temperature
with stirring. Moist sodium sulfate is added, followed by water (10 ml), and the reaction mixture is filtered. The products
are then extracted from the filtrate by methylene chloride or
chloroform; further purification, if necessary, is by column
chromatography.
Received: October 8, 1979 [Z 439 IE]
German version: Angew. Chem. 92, 321 (1980)
[I] H. Alper, H. N. Paik, J . Org. Chem. 42. 3522 (1977).
121 E. C. Ashby, J. J. Lin. J. Org. Chem. 43, 1263, 2567 (1978); F. Solo, Y. Mori,
M. Solo, Tetrahedron Lett. 1979, 1405; F. Sam in Y. Ishii, M. Tsulsui:Fundamental Research in Homogeneous Catalysis. Vol. 2. Plenum Press, New York
1978, p. 81, and references cited therein.
Similar reactions also occur with primary and secondary
amines and, more slowly, with thiols. Thus, by choosing a
suitable substrate, a product may be made with almost any
desired spatial arrangement of fluorophosphino groups. Two
typical syntheses are described, that of bis[2-(difluorophosphinoxy)ethyl]sulfide (5)and that of phosphoryltrioxytris(difluorophosphane) (6).
Experimental
Preparation of (5): Compound (I)['] (4 mmol) is condensed into a glass ampoule (at -196°C) containing
S(CH2CH20H),(1.7 mmol) and the reagents are warmed to
room temperature for 45 min. After the volatile products
have been distilled out at - 78 "C, (5) (1.4 mmol, 80% yield)
is obtained in a pure form by distillation in vacuo at room
temperature. Subsequent manipulation of (5)is by syringe in
an inert atmosphere@].
Preparation of (6): Compound ( I ) (16.5 mmol) is condensed into a glass ampoule (at - 196 "C) containing 100%
H,P04 (4.5 mmol). On warming to room temperature, effervescence occurs and the solid material disappears. After 30
min, the volatile products are removed, and (6) (4.3 mmol,
95% yield) is obtained as a clear liquid, involatile at - 45 "C,
by fractional condensation in vacuoI'1.
Received September 3, 1979 [Z 440 IE]
German version: Angew. Chem. 92, 323 (1980)
General Method for Preparation of Multidentate
Fluorophosphane Ligandd"]
J. F. Nixon, Adv. Inorg. Chem. Radiochem. 13, 363 (1970), and references
cited therein.
C. A. McAulCfe, W. Leuason: Phosphine, Arsine and Stibine Complexes of
the Transition Elements. Elsevier, Amsterdam, 1979, 9. 310, and references
cited therein.
R. B. King, J. Gimeno, J . Chem. SOC.Chem. Commun. 1977, 142.
M. G. Newton, R. 8. King, M. Chang, N . S. Pantaleo, J. Gimeno, J. Chem.
SOC.Chem. Commun. 177, 531.
Preparation, see D. E. J. Arnold, E. R. Cromre. D. W. H. Rankin, J . Chem.
SOC.Dalton Trans. 1977, 1999.
'H-NMR (CDCI,): 6=2.81 (4H, t, J = 7 Hz),4.19(4H, q, J P H = J H H = ~ Hz);
"CC-NMR:6 r 3 2 . 4 (d. J p c = 3 Hz). 62.1 ( t x d , J ~ c = 9Hz, J p c = 3 Hz); 19FNMR 6 = -48 (d, J ~ = t 2 9 4Hz); "P-NMR: 6=112 (1x1, Jpp=1294 Hz,
J P H = 7Hz); IR (film): 2970, 2910, 1465, 1425, 1405, 1295, 1200, 1050, 1005,
965. 805. 760, 560 c m - '
"P-NMR (CDCL): 6 = 108 (3P, t x d , JpF=1385 Hz, Jpy=28 Hz),-41 (1 P.
m); IYF-NMR:6 = -38 ( d x d , JPF=1384 Hz, JpF=tOHz); IR (gas): 1345,
1042,988,867,728.529,469,399 cm- '; m. p. - 19 "C, vapor pressure at 0 "C,
By Ernest R. Cromie, George Hunter, and David W: H
Rankin"'
Although fluorophosphanes are well known as monodentate ligands[", very little work has been done with multidentate fluorophosphanes[21,and few suitable ligands are readily
available. They are of interest because they can bond in a
number of different ways: for example, CH3N(PF2)2may
form two bonds to a single metal atomI3Jor a bridge between
two metal atomsL4].We report here a reaction which may be
used to prepare a wide variety of fluorophosphanes which
may prove to be useful multidentate ligands.
We have observed that bis(difluorophosphino)sulfide (I)[']
reacts with organic and inorganic mono- and polyhydroxy
compounds (2) to give difluorophosphane sulfides (3) and
the desired difluorophosphinoxy compounds (4).
S(PF2)z + ROH
(1)
(2)
+
SPFZH + ROPF2
(3)
(4)
The product (4) is normally much less volatile than (3), and
may therefore easily be obtained in a pure form. Use of an
excess of hydroxy compound (2) should be avoided, as a slow
substitution reaction of (3) occurs, yielding less volatile products (SPFHR, SPHR2).
The group R may be almost any organic group, such as
primary, secondary, or tertiary alkyl, aryl or acyl, and inorganic "hydroxides" such as phosphoric acid may also be
used. With 1,2-diols PF3 is eliminated from the initial products to give 2-fluorodioxaphospholanes,which may also be
of interest as ligands.
[*] Dr. D. W. H. Rankin, E. R. Cromie, G. Hunter
Department of Chemistry. University of Edinburgh
West Mains Road, Edinburgh EH9 3JJ (Scotland)
[*'I We thank the Science Research Council for research studentships (to E. R.
C. and G. H.).
316
1 torr.
@ Veriag Chemie, GmbH, 6940 Weinheim, 1980
I9'Pt-NMR Spectroscopy of Catalytically Active
Complexes. Extremely Large Spin-Spin Coupling
between Platinum and Tin'"'
By Karl-H. A . Ostoja Starzewski and Paul S. Pregosin[']
Platinum-phosphane complexes in combination with
tin(r1) chloride are excellent homogeneous catalysts for hydrogenation and hydroformylation reactions'']. As part of
our study''] on the NMR characteristics of the active intermediates formed in these reactions, we found IJ(i9sPtit9Sn)
in tran~-[PtCl(SnCl~)(PEt~)~]
to be 28 954 Hz, which represents the largest one-bond spin-spin coupling constant ever observed (cf. Table
['I
Dr. P. S. Pregosin, Dr. K.-H. A. Ostoja Starzewski
Laboratorium fur Anorganische Chemie, ETH-Zenlrum
Universitatstrasse 6. CH-8092 Ziinch (Switzerland)
["I
This work was supported by the Swiss National Science Foundation. We
thank Prof. L. M Venand for helpful discussions.
OS?0-0833/S0/0404-031~ $ 02S0/0
Angew. Chem. I n l . Ed. Engl. 19 (1980) No. 4
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mild, triethylhydroborat, metali, sodium, desulfurization, thiol, exceedingly, transitional, chloride
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