An efficient stereoselective synthesis of sphingosine

Article abstract of DOI:10.1055/s-1998-4482

A stereocontrolled synthesis of D-(+)-erythro-sphingosine (1), starting from D-xylose as chiral pool material and employing the addition-fragmentation reaction of tosyl hydrazone of 2,3:4,5-di-O-isopropylidene-D-xylose as a key step for the chain extension with concomitant trans-selective C=C bond formation, is described.

Full text of DOI:10.1055/s-1998-4482

33
SHORT PAPERS
An Efficient Stereoselective Synthesis of Sphingosine
Pradeep Kumar, Richard R. Schmidt*
Fakultät Chemie, Universität Konstanz, Postfach 5560 M 725, D-78457 Konstanz, Germany
Fax: +49(7531)883135
Received 5 May 1997; revised 18 July 1997
step3 in order to construct the required trans C=C bond
with concomitant chain extension in one step.
A stereocontrolled synthesis of D-(+)-erythro-sphingosine (1),
starting from Dxylose as chiral pool material and employing the
addition–fragmentation reaction of tosyl hydrazone of 2,3:4,5-di-O-
isopropylidene-D-xylose as a key step for the chain extension with As shown in the Scheme, 2,3:4,5-di-O-isopropylidene-al-
concomitant trans-selective C=C bond formation, is described.
dehydo-D-xylose 4 was prepared following literature pro-
cedures in three steps. Thus, D-xylose was converted into
Sphingosine (1), phytosphingosine and the biosynthetic
precursor of both, sphinganine, are most abundant long-
chain amino alcohols possessing generally 18 or 20 car-
bon atoms. The occurrence of various structural modifica-
tions of the sphingosine moiety in nature and the
requirement of structurally varied derivatives for biologi-
cal testing led us to investigate sphingosine syntheses
based on tosyl hydrazones of sugars (Scheme). Various
D-xylose diethyl dithioacetal 2 by treatment with
ethanethiol in quantitative yield.4 Reaction of 2 with ace-
tone in the presence of catalytic amounts of sulfuric acid
gave 3 (73%) which on deprotection of the thiol group
with HgO/HgC12 furnished 4 in good yield.5 The subse-
quent treatment of the aldehyde 4 with tosyl hydrazide af-
forded the corresponding hydrazone 5 (76%) which was
subjected to the key addition–fragmentation reaction. The
methods for the synthesis of sphingosine and its analogues
have been documented in the literature.1 Recently, we
have reported an oxa-Cope rearrangement route as a com-
petitive alternative to the previously published sphin-
gosine syntheses.2 However, a simple and efficient large
scale synthesis is still desirable. Thus, it was envisaged to
plan a stereoselective synthesis from readily available car-
bohydrate precursors. The addition–fragmentation reac-
tion of tosyl hydrazone of sugar was employed as a key
reaction of tosyl hydrazone 5 with 3 equivalents of pre-
formed Grignard reagent prepared from 1-bromotridecane
afforded only the desired trans-allylic alcohol 6, yet in
moderate yield. Thus, the generally required trans C=C
bond was constructed with concomitant chain elongation
in one step. The stereoselective formation of (E)-alkene
was determined by 1H NMR and decoupling experiments.
Further, the synthesis of sphingosine (1) from 6 was
achieved employing a series of high-yielding functional

34
Short Papers
SYNTHESIS
MS: m/z(%) = (M+-1) 397(24.11), 383(48.23), 325(9.41), 283(8.82),
268(10), 243(15.88), 185(13.52), 155(13.52), 139(17.64),
113(27.64), 101(48.23), 91(61.17), 59(72.35).
Anal. calcd for C18H26N2O6S (398.45): C, 54.26; H, 6.58; N, 7.03; S,
8.05, Found: C, 54.02; H, 6.47; N, 7.28; S, 8.26.
group transformations (Scheme). The choice of introduc-
ing a readily removable benzoyl protective group seemed
to be more appropriate. Indeed, the hydroxyl group pro-
tection of 6 with benzoyl cyanide/triethylamine (® 7)
proceeded smoothly in high yield. Subsequent removal of
the isopropylidene group under acid catalysis furnished
the diol 8, Selective 1-O-protection was carried out at –
70°C using benzoyl cyanide/triethylamine to afford the
1,3-di-O-benzoylated compound 9. However, our attempt
to obtain 9 by direct regioselective 1,3-O-protection from
13 was unsuccessful. Compound 9 was then converted
into 2-O-mesylate derivative 10 which on reaction with
sodium azide in DMF afforded the corresponding 1,3-di-
O-benzoylated sphingosine 11. Removal of the benzoyl
group with sodium methoxide in methanol (Zemplén con-
ditions)6 furnished the azido sphingosine 12 which was in
all aspects identical with the reported compound.7 Trans-
formation into 1 could be readily performed as previously
described.8
(2R,3R,4E)-1,2-O-Isopropylideneoctadec-4-ene-1,2,3-triol (6):
To a stirred suspension of 5 (1.4 g, 3.51 mmol) in anhyd Et2O
(25 mL), maintained at 0°C under N2 was added dropwise preformed
tridecylmagnesium bromide (10.55 mL, 10.53 mmol, 1 M solution in
Et2O). The mixture was stirred at 0°C for 0.5 h, slowly warmed to r.t.
and stirred overnight at this temperature. Subsequently, the mixture
was hydrolyzed by the addition of ice-cold 1 M NH4Cl (10 mL) so-
lution. The organic phase was separated and the aqueous phase was
saturated with brine and subsequently extracted with Et2O (2 ´ 50 mL).
The combined organic phases were dried (Na2SO4), filtered and con-
centrated. Column chromatography using petroleum ether/EtOAc
(10:1) afforded 6 (0.57 g, 48%) as a colorless oil. TLC (silica gel, pe-
troleum ether/EtOAc, 8:2): Rƒ = 0.37; [a]D20 –1.3 (c = 1.0, CHCl3).
1H NMR (250 MHz, CDCl3): d = 0.85 (t, 3 H, CH3, J = 6.6 Hz), 1 .15–
1.30 (m, 22 H, 11 CH2), 1.34 (s, 3 H, CH3CCH3), 1.42 (s, 3 H,
CH3CCH3), 2.0 (dt, 2 H, CH=CHCH2, J = 6.9, 7.5 Hz), 2.3 (br s, 1 H,
CHOH), 3,69 (m, 1 H, OCH2), 3.94 (m, 3 H, OCH2, OCHCH2,
CHOH), 5.36 (dd, 1 H, CH=CHCH2, J = 6.9, 15.4 Hz), 5.77 (dt,
CH=CHCH2, J = 6.7, 15.3 Hz).
Furthermore, in an alternative approach for the formal
synthesis of sphingosine, the cleavage of the isopropy-
lidene group of 6 was carried out under acid catalysis to
furnish the triol 13. The benzylidene protection of 13 was
effected with benzaldehyde dimethylacetal in the pres-
ence of a catalytic amount of p-TSA to afford a mixture of
1,3- and 1,2-benzylidene compound in 9:1 ratio, The de-
sired major 1,3-benzylidene compound 14 was separated
by silica gel column chromatography. As the synthesis of
sphingosine from 14 has already been reported,7,8 the for-
mal synthesis of sphingosine 1 was completed.
MS: m/z(%) = M+-OH 323(8.82), 297(3.52), 239(30.58), 201(6.47),
101(100).
FAB-MAS
=
[2M]Na+ 703(5), [M]Na+ 363(94.28), 323(50),
265(7.85), 176(15), 154(14.28), 101(100).
Anal. calcd for C21H40O3 (340.53): C, 74.06; H, 11.84. Found: C,
74.10; H, 11.73.
(2R,3R,4E)-1,2-O-Isopropylidene-3-O-benzoyloctadec-4-ene-
1,2,3-triol (7):
To a solution of 6 (100 mg, 0.29 mmol) in anhyd CH2Cl2 (4 mL) con-
taining anhyd Et3N (0.5 mL), maintained at 0°C under N2 was added
dropwise a solution of benzoyl cyanide (42.48 mg, 0.32 mmol) dis-
solved in anhyd CH2Cl2 (1 mL) and the mixture was stirred for 2 h at
0°C and then 4 h at r.t. The excess of benzoyl cyanide was destroyed
In summary, a highly stereocontrolled synthesis of D
(+)-erythro-sphingosine from a sugar precursor by a
simple and operationally feasible procedure was by adding MeOH (1 mL), the solvent was concentrated in vacuo. The
residue was taken up in EtOAc (5 mL) and washed with sat. aq
NaHCO3 (2 ´ 5 mL). The organic phase was dried (Na2SO4), filtered
and concentrated; column chromatography over silica gel with petro-
achieved. The merits of this synthesis are high-yielding
reaction steps, ready access to the required trans C=C
bond and the various possibilities available for struc-
tural modifications.
leum ether/EtOAc, (9.5:0.5) gave 7 (111 mg, 85%) as a colorless oil.
TLC (silica gel, petroleum ether/EtOAc, 8:2): Rƒ = 0.75; [a]D20 +17.5
(c = 1.0, CHCl3).
Solvents were purified and dried by standard procedures before use;
petroleum ether of boiling range 35–70°C was used. Melting points
are uncorrected.1H NMR spectra: Bruker AC 250, internal standard
tetramethylsilane (TMS): J values in Hz. Mass spectra: Varian MAT
312 (70eV), Varian MAT 312/AMD 5000 FAB. Flash chromatogra-
phy: silica gel 60 (Baker, 0.03–0.06 mm) at a pressure of 0.3 bar. Thin
layer chromatography (TLC): Foil plates, silica gel 60 F254 (Merck;
layer thickness 0.2 mm); detection by treatment with a solution of 20 g
of ammonium molybdate and 0.4 g of cerium(IV) sulfate in 400 mL
of 10% sulfuric acid and heating at 150°C. Elemental analyses: He-
raeus CHN-O-Rapid. Optical rotations: Perkin-Elmer polarimeter
241/MS, 1 dm cell.
1H NMR (250 MHz, CDCl3): d = 0.88 (t, 3 H, CH3, J = 6.6 Hz), 1.23–
l.33 (m, 22 H, 11 CH2), 1.37 (s, 3 H, CH3CCH3), 1.45 (s, 3 H,
CH3CCH3), 2.04 (dt, 2 H, CH=CHCH2, J = 6.9,7.3 Hz), 3.83 (m,1 H,
OCH2), 4.04 (m, 1 H, OCH2), 4.34 (m, 1 H, OCHCH2O), 5.49 (m,
2 H, CH=CHCH2, CHOCOPh), 5.94 (dt, 1 H, CH=CHCH2, J = 6.7,
14.3 Hz), 7.40–7.46 (m, 2 H, Ph), 7.52–7.58 (m, 1 H, Ph), 8.05–8.08
(m, 2 H, Ph).
MS: m/z(%) = M+ 444(20), 429(100), 412(2.85), 397(7.85),
386(7. 14), 356(3.57), 343(5), 322(22.14), 281(6.42), 264(68.57),
237(14.28), 211(10.71), 201(62.14).
Anal. calcd for C28H44O4 (444.63): C, 75.63; H, 9.97. Found: C,
75.34; H, 10.01.
2,3:4,5-Di-O-isopropylidene-D-xylose Tosylhydrazone (5):
A mixture of 4 (5.17 g, 22.47 mmol) and p-toluenesulfonyl hydrazide
(4.18 g, 22.47 mmol) in anhyd MeOH (37.5 mL) was stirred for 4 h
at r.t. under N2. The hydrazone 5 thus separated as white solid was fil-
tered, washed with anhyd Et2O (20 mL), dried and used for further re-
action without purification. Yield (7.16 g, 76%). TLC (silica gel,
petroleum ether/EtOAc, 1:1): Rƒ = 0.52; mp 126°C; [a]D20 –3.6 (c =
l .0, CHCl3).
(2R,3R,4E)-3-O-Benzoyloctadec-4-ene-1,2,3-triol (8):
To a solution of 7 (330 mg, 0.74 mmol) in THF (25 mL) was added
1N HCl (3 mL), and the mixture was heated under stirring for 12 h at
60°C. Subsequently the solvent was concentrated in vacuo and the
residue was taken up in Et2O and the solution was neutralized with
sat. aq NaHCO3 (15 mL). The organic layer was washed with H2O,
dried (Na2SO4) and concentrated; column chromatography over silica
gel using petroleum ether/acetone (9:1) gave 8 (230 mg, 77%) as a
colorless oil. TLC (silica gel, petroleum ether/acetone, 8:2): Rƒ =
0.32; [a]D20 +l3.1 (c = 1.0, CHCl3).
1H NMR (250 MHz, CDCl3): d = 1.32 (s, 3 H, CH3), 1.33 (s, 3 H,
CH3), 1.34 (s, 3 H, CH3), 1.39 (s, 3 H, CH3), 2.40 (s, 3 H,
SO2C6H4CH3), 3.45 (dd, 1 H, J = 7.2, 8.5 Hz, H-3), 3.82 (m, 2 H,
OCH2, H-5), 4.02 (m, 1 H, OCH2CHO, H-4), 4.28 (dd, 1 H, J = 6, 7.8
Hz, H-2), 7.08 (d, 1 H, CH=N, J = 5.9 Hz), 7.28–7.31 (m, 2 H, Ph),
7.78–7.83 (m, 2 H, Ph), 8.08 (s, 1 H, NH).
1H NMR (250 MHz, CDCl3): d = 0.88 (t, 3 H, CH3, J = 6.6 Hz), 1.23–
l.36 (m, 22 H, 11 CH2), 2.05 (dt, 2 H, CH=CHCH2, J = 6.9, 6.9 Hz),
2.36 (br s, 2 H, OH), 3.67 (m, 2 H, OCH2), 3.92 (m, 1 H, CHOH), 5.55

January 1998
SYNTHESIS
35
(m, 2 H, CH=CHCH2, CHOCOPh), 5.93 (dt, 1 H, CH=CHCH2, J = Anal. calcd for C32H43N3O4 (533.66): C, 72,02; H, 8. 12; N, 7.87.
6.7, 14.5 Hz), 7.4l–7.47 (m, 2 H, Ph), 7.54–7.61 (m, 1 H, Ph), 8.02– Found: C, 71.87; H, 8.16; N, 7.55.
8.08 (m, 2 H, Ph).
MS: m/z(%) = M+ 404(2.35), 373(5.29), 344(80), 264(15.29), (2S,3R,4E)-2-Azidooctadec-4-ene-1,3-diol (12):
252(85.29), 239(62.35), 222(36.47), 194(23.52), 165(30.58), 105(100). A solution of NaOMe in MeOH (1 mL, 0.2 M) was added to 11
Anal. calcd for C25H40O4 (404.57): C, 74.21; H, 9.97. Found: C, (58 mg, 0.11 mmol) in anhyd MeOH (2 mL) and the mixture was
73.76; H, 9.80.
stirred for 2 h at r.t. Subsequently, it was neutralized with ion-ex-
change resin Amberlite IR 120, H+-form (20 mg). The resin was fil-
tered off and the filtrate concentrated in vacuo; column
chromatographic purification of the residue using CH2Cl2/MeOH
(9.75:0.25) gave 12 (35 mg, 98%) as a white solid. TLC (silica gel,
CH2Cl2/MeOH, 9.5:0.5): Rƒ = 0.45; mp 49 °C; [a]D20 –29.1 (c = 1,
CHCl3); ref. 7: mp. 49–50°C; [a]D20 –32.9 (c = 4. CHCl3). Spectro-
scopic properties (1H NMR, Mass) were in accord with those de-
scribed.7
(2R,3R,4E)-1,3-Di-O-benzoyloctadec-4-ene-1,2,3-trio1 (9):
To a solution of 8 (230 mg, 0.57 mmol) in anhyd THF (23 mL) con-
taining anhyd Et3N (1.15 mL), maintained at –70°C under an N2 at-
mosphere, was added dropwise a solution of benzoyl cyanide (80 mg,
0.61 mmol) in anhyd THF (2 mL) and the mixture was stirred for 3 h
at –70°C. The excess of benzoyl cyanide was destroyed by adding
MeOH (1 mL), the solvent was concentrated in vacuo. The residue
was taken up in EtOAc (15 mL) and washed with sat. aq NaHCO3
(2x15 mL). The organic phase was dried (Na2SO4), and concentrated;
column chromatography over silica gel with petroleum ether/acetone
(9:1) gave 9 (231 mg, 80%) as a colorless oil. TLC (silica gel, pe-
troleum ether/acetone, 7:3): Rƒ = 0.76; [a]D20 + 9.5 (c = 1.0, CHCl3).
1H NMR (250 MHz, CDCl3): d = 0.88 (t, 3 H, CH3, J = 6.6 Hz), 1.22–
1.42 (m, 22 H, 11 CH2), 2.09 (dt, 2 H, CH=CHCH2, J = 6.7, 6.9 Hz),
2.55 (br s, 1 H, OH), 4.19 (m, 1 H, CHOH). 4.48 (m, 2 H, OCH2), 5.64
(m, 2 H, CH=CHCH2, CHOCOPh), 5.97 (dt, 1 H, CH=CHCH2, J =
l4.5, 6.7 Hz), 7.38–7.47 (m, 4 H, Ph), 7,54–7.60 (m, 2 H, Ph), 7.97–
8.08 (m, 4 H, Ph).
(2S,3R,4E)-Octadec-4-ene-1,2,3-triol (13):
To a solution of 6 (300 mg, 0.88 mmol) in anhyd MeOH (10 mL) was
added p-toluenesulfonic acid (10 mg), and the mixture was stirred at
r.t. for 24 h. Subsequently the solvent was concentrated in vacuo and
the residue was taken up in CHCl3 and the solution was neutralized
with sat. aq NaHCO3 (10 mL); the organic phase was separated,
washed with H2O, dried (Na2SO4) and concentrated. Column chro-
matography using petroleum ether/acetone (7:3) afforded 13 (185 mg,
70%) as a white solid. TLC (silica gel, petroleum ether/acetone, 7:3):
Rƒ = 0.49; mp 59–60°C; [[a]D20 –0.3 (c = 1, CHCl3).
MS:m/z(%)=M+508(8.23),M+-H2O490(5.88),386(31.47),356(27.60),
343(12.35), 264(8.82), 251(5.29), 165(78.82), 105(100), 77(32.35).
Anal. calcd for C32H44O5 (508.67): C, 75.55; H, 8.72. Found: C,
75.67; H, 8.68.
1H NMR (250 MHz): 0.85 (t, 3 H, CH3, J = 6.6 Hz), 1.16–1.40 (m, 22
H, 11 CH2), 2.02 (dt, CH=CHCH2, J = 6.7, 6.7 Hz), 2.96 (br s, 2 H, 2
OH), 3.53–3.70 (m, 3 H, OCH2, CH=CHCHOH), 4.07 (m, 1 H,
CH2CHOH), 5.44 (dd, 1 H, CH=CHCH2, J = 7.3, 15.6 Hz), 5.74 (dt,
1 H, CH=CHCH2, J = 6.7. 15.4 Hz),
FAB:MS = [2M]Na+ 623(2.14), 473(4.28), 345(17.14), [M]Na+
323(100), 200(10.7), 173(20),
(2R,3R,4E)-1,3-Di-O-benzoyl-2-O-methylsulfonyloctadec-4-ene-
1,2,3-triol (10):
Methanesulfonyl chloride (0.06 g, 0.52 mmol) was added under N2 to
a solution of 9 (0.175 g, 0,34 mmol) in anhyd pyridine (2 mL). The
mixture was heated under stirring for 12 h at 70–80°C. The excess of
mesyl chloride was destroyed by adding a small amount of MeOH.
The above mixture was cooled to r.t. and pyridine was removed by co-
evaporation with toluene. Purification of the residue by chromatogra-
phy over silica gel with petroleum ether/EtOAc (9:1) gave 10 (149
mg, 75%) as a colorless oil. TLC (silica gel, petroleum ether/EtOAc,
8:2): Rƒ = 0.52; [a]D20 + 5.2 (c = 1, CHCl3).
Anal. calcd for C18H36O3 (300.47); C, 71.95; H, 12.08. Found: C,
72.17; H, 12.10.
(2S,3R,4E)-1,3-O-Benzylideneoctadec-4-ene-1,2,3-trio1 (14):
To a solution of 13 (71 mg, 0.24 mmol) in CH2Cl2 (5 mL) was added
p-toluenesulfonic acid (5 mg) and benzaldehyde dimethylacetal
(0.043 g, 0.0425 mL, 0.28 mmol); the mixture was stirred at r.t. for
5 h. Subsequently it was neutralized with sat. aq NaHCO3 (5 mL) and
washed with aq NaHSO3 to remove traces of benzaldehyde. The or-
ganic phase was separated, washed with H2O, dried (Na2SO4) and
concentrated. Column chromatography over silica gel using petro-
leum ether/acetone (9:1) furnished 14 as major product (55 mg, 60%).
TLC (silica gel, petroleum ether/acetone, 9:1): Rƒ = 0.42; mp 56–
57 °C; ref. 7: mp 54–55 °C. Spectroscopic properties (1H NMR, Mass)
were in accord with those described.7
1H NMR (250 MHz, CDCl3): d = 0.85 (t, 3 H, CH3, J = 6.6 Hz), 1.20–
l.40 (m, 22 H, 11 CH2), 2.04 (dt, 2 H, CH=CHCH2, J = 6.7, 6.7 Hz),
2.97 (s, 3 H, SCH3), 4.45 (m, 1 H, OCH2), 4.67 (m, 1 H, OCH2), 5.20
(m, 1 H, CHOMs), 5.51 (dd, 1 H, CH=CHCH2, J = 7.7, 15.4 Hz), 5.78
(dd, 1 H, CHOCOPh, J = 7.4, 7.4 Hz), 6.02 (dt, 1 H, CH=CHCH2,
J = 6.7, 15.3 Hz), 7.40–7.60 (m, 6 H, Ph), 8.04–8.08 (m, 4 H, Ph).
MS: m/z(%) = M+ 586(2.85), M+-OSO2CH3 491(21.42), 465(2.85),
385(22.14), 368(40.71), 343(11.42), 305(3.57), 264(26.42),
246(18.57), 200(6.42), 122(30), 105(100), 91(25), 77(98.57), 67(20),
55(28.57), 43(53.57).
This work was supported by the Deutsche Forschungsgemeinschaft
and the Fonds der Chemischen Industrie. P. K. is grateful to the Alex-
ander von Humboldtfoundation for a research fellowship.
Anal. calcd for C33H46O7S (586.76): C, 67.55; H, 7.90; S, 5.46.
Found: C, 67.16; H, 8.06; S, 5.74.
(2S,3R,4E)-2-Azido-1,3-di-O-benzoyloctadec-4-ene-1,3-diol (11):
To a solution of 10 (110 mg, 0.19 mmol) in anhyd DMF (5 mL) was
added NaN3 (70 mg, 1.09 mmol), and the mixture was heated under
stirring at 100°C for 36 h. The mixture was cooled, diluted with Et2O,
washed with H2O and brine, The organic phase was separated, dried
(Na2SO4) and concentrated. Purification of the residue over silica gel
column with petroleum ether/EtOAc (9.5:0.5) gave 11 (90 mg, 90%)
as a colorless oil. TLC (silica gel, petroleum ether/EtOAc, 9:1): Rƒ =
0.77; [a]D20 – 28.9 (c = 1, CHCl3),
(1) Wild, R.; Schmidt, R. R. Tetrahedron Asymm. 1994, 5, 2195; and
references therein.
Li, Y-Long; Wu, Y-Lin Liebigs Ann. 1996, 2079; and references
therein.
(2) Schmidt, R.R,; Bär, T.; Wild, R. Synthesis 1995, 868; and ref-
erences therein.
(3) Chandrasekhar, S.; Takhi, M.; Yadav, J. S. Tetrahedron Lett.
1995, 36, 5071.
(4) Asbun, W.; Binkley, S. B. J. Org. Chem. 1966, 31, 2215.
Wolfrom, M. L.; Newlin, M. R.; Stahly, E. E. J. Am. Chem. Soc.
1931, 53, 4379.
(5) Kochetkov, N. K.; Dmitriev, B. A. Tetrahedron 1965, 21, 803.
(6) Zemplén, G. Ber. Dtsch. Chem. Ges. 1927, 60, 1555.
(7) Zimmermann, P.; Schmidt, R. R. Liebigs Ann. Chem. 1988, 663.
(8) Schmidt, R. R.;Zimmermann, P. TetrahedronLett. 1986, 27, 481.
1H NMR (250 MHz, CDCl3): d = 0.85 (t, 3 H, CH3, J = 6.6 Hz), 1.21–
1 .40 (m, 22 H, 11 CH2), 2.06 (dt, 2 H, CH=CHCH2, J = 7, 7 Hz), 4.12
(m, 1 H, CHN3), 4.34 (m, 1 H, OCH2), 4,5 (m, 1 H, OCH2), 5.62 (m,
2 H, CH=CHCH2, CHOCOPh), 5.96 (dt, 1 H, CH=CHCH2, J = 6.7,
14.7 Hz), 7.40–7.60 (m, 6 H, Ph), 8.02–8,07 (m, 4 H, Ph).
MS: m/z(%) = M+ 533(5), M+-N2 505(20), M+-N3 491(100), 343
(42.85), 262(17.14), 190(83.57), 105(100), 77(81.42), 43(32.85).