One-step conversion of aldehydes to oxazolines and 5,6-dihydro-4H-1,3-oxazines using 1,2- and 1,3-azido alcohols

Article abstract of DOI:10.1021/jo9521256

The reactions of 1,2- and 1,3-hydroxy azides with aldehydes under acidic conditions were examined. A variety of Lewis acids were examined, of which BF₃·OEt₂ was found the most convenient. Trimethylsilyl ether derivatives of the alcohols could also be reacted using trimethylsilyl triflate as the promoter. Twenty-five examples that proceed in moderate to quantitative yields are reported.

Full text of DOI:10.1021/jo9521256

2484
J . Org. Chem. 1996, 61, 2484-2487
On e-Step Con ver sion of Ald eh yd es to Oxa zolin es a n d
5,6-Dih yd r o-4H-1,3-oxa zin es Usin g 1,2- a n d 1,3-Azid o Alcoh ols
J ennifer G. Badiang and J effrey Aube´*
Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66045-2506
Received November 30, 1995X
The reactions of 1,2- and 1,3-hydroxy azides with aldehydes under acidic conditions were examined.
A variety of Lewis acids were examined, of which BF3‚OEt2 was found the most convenient.
Trimethylsilyl ether derivatives of the alcohols could also be reacted using trimethylsilyl triflate
as the promoter. Twenty-five examples that proceed in moderate to quantitative yields are reported.
Sch em e 1
In 1955, Boyer and co-workers found that the reaction
of alkyl azides with aromatic aldehydes could be carried
out using H2SO4 in benzene to afford amides in 10-25%
yields (eq 1).1 In contrast, using 2-azidoethanol (1) or
3-azido-1-propanol (2a ) under similar conditions afforded
oxazolines or dihydrooxazines, respectively, with much
greater efficiency (eq 2).
As originally disclosed, the Boyer reaction was reported
to be limited severely in scope, resulting in good yields
only when electron-poor aldehydes were used as reac-
tants. Recently, we reported a similar reaction using
ketones.3 In the present paper, we disclose that modi-
fication of Boyer’s original reaction conditions allows for
a substantial extension of the scope of the process. Thus,
reactions of a range of aldehydes with azido alcohols 1
and 2a and (()-1-azido-2-phenylethanol (3) result in
efficient routes to a variety of oxazolines and dihydroox-
azines. Oxazolines are subunits in a number of natural
products and have found use as asymmetric catalysts and
as peptidomimetics.4
These authors proposed that both reactions proceeded
via mechanisms involving initial nitrogen attack, and
attributed better yields of the latter process to increased
acid stability of the hydroxy azides.1b,c With the benefit
of hindsight and mindful of recent developments in
reactions of alkyl azides with carbonyl and carbocation
electrophiles,2 we recently proposed the mechanism
shown in Scheme 1.2g In this scenario, initial hemiketal
formation is followed by dehydration to set up an in-
tramolecular attack of the azide on the resulting oxonium
ion. Elimination of H+ and N2 directly affords the
heterocyclic products. An alternative mechanism involv-
ing a 1,2-hydride shift coupled with N2 loss followed by
proton loss is also possible, but seems less likely in light
of the poor migratory ability of H in similar processes.2e,3
Resu lts a n d Discu ssion
Our first goal was to see whether Lewis acid promotion
would overcome the reported limitations of the reaction
to electron-poor aromatics. In particular, we hoped to
extend the reach of this process to include 2-alkyl
heterocycles. Using benzaldehyde and hexanal as test
cases, we found that 1,3-azidopropanol 2a underwent
smooth addition using a variety of Lewis acids (Table 1).
To our slight surprise, the list of effective reagents for
the reaction of hexanal included H2SO4, in spite of the
previous report to the contrary.1a We also established,
following the precedent of Marko´,5 that 1-azido-3-[(tri-
* Address correspondence to this author. Tel: (913) 864-4496. Fax
(913) 864-5326. E-mail: jaube@rx.pharm.ukans.edu.
X Abstract published in Advance ACS Abstracts, March 15, 1996.
(1) (a) Boyer, J . H.; Hamer, J . J . Am. Chem. Soc. 1955, 77, 951-
954. (b) Boyer, J . H.; Canter, F. C.; Hamer, J .; Putney, R. K. J . Am.
Chem. Soc. 1956, 78, 325-327. (c) Boyer, J . H.; Morgan, L. R., J r. J .
Org. Chem. 1959, 24, 561-562.
(2) (a) Aube´, J .; Milligan, G. L.; Mossman, C. J . J . Org. Chem. 1992,
57, 1635-1637. (b) Aube´, J .; Rafferty, P. S.; Milligan, G. L. Heterocycles
1993, 35, 1141-1147. (c) Aube´, J .; Milligan, G. L. J . Am. Chem. Soc.
1991, 113, 8965-8966. (d) Pearson, W. H.; Schkeryantz, J . M.
Tetrahedron Lett. 1992, 33, 5291-5294. (e) Pearson, W. H.; Wala-
valkar, R.; Schkeryantz, J . M.; Fang, W.-K.; Blickensdorf, J . D. J . Am.
Chem. Soc. 1993, 115, 10183-10194. (f) Pearson, W. H.; Fang, W.-K.;
Kampf, J . W. J . Org. Chem. 1994, 59, 2682-2684. (g) Aube´, J .;
Milligan, G. L.; Mossman, C. J . J . Am. Chem. Soc. 1995, 117, 10449-
10459.
(3) Aube´, J .; Gracias, V.; Milligan, G. L. J . Am. Chem. Soc. 1995,
117, 8047-8048.
(4) For reviews, see: (a) Frump, J . A. Chem. Rev. 1971, 71, 483-
505. (b) The Chemistry of Heterocyclic Compounds; Turchi, J ., Ed.; J ohn
Wiley and Sons, Inc.: New York, 1986; Vol. 45. (c) Gant, T. G.; Meyers,
A. I. Tetrahedron 1994, 50, 2297-2360.
(5) Marko´, I. E.; Mekhalfia, A. Tetrahedron Lett. 1991, 32, 4779-
4782.
0022-3263/96/1961-2484$12.00/0 © 1996 American Chemical Society

Conversion of Aldehydes to Oxazolines and Dihydrooxazines
J . Org. Chem., Vol. 61, No. 7, 1996 2485
Ta ble 1. Effect of Lew is Acid on th e Syn th esis of
Ta ble 2. Rea ction s of Azid oh yd r in s w ith Ald eh yd es in
5,6-Dih yd r o-4H- 1,3-oxa zin es
th e P r esen ce of BF 3‚OEt2
methylsilyl)oxypropane (2b) could be directly reacted
with aldehydes using TMSOTf catalysis. Of the various
Lewis acids, BF3‚OEt2 was judged most convenient in
terms of availability, effectiveness, and ease of workup.
Accordingly, a range of aldehydes were subjected to
reactions with 1, 2a , and 3 in the presence of BF3‚OEt2
(Table 2). Overall, good yields could be obtained for the
entire range of aromaticsincluding electron-richsand
aliphatic aldehydes examined. 1H and 13C NMR spectra
show that the products were obtained in good purity.
However, many of these compounds were hydrolyzed to
corresponding amides upon exposure to atmospheric
moisture.
formation of competing products. Still, moderate yields
could be obtained using favorable substrates (e.g., eq 4).
Two additional examples merit particular mention.
First, p-acetylbenzaldehyde was prepared and subjected
to the reaction conditions to determine the chemoselec-
tivity of the reaction. Clean reaction of the aldehyde in
the presence of the ketone was observed in this case (eq
3).
Despite this limitation, the reactions of azido alcohols
with aldehydes show promise for the preparation of a
variety of useful heterocycles.
Exp er im en ta l Section
General methods have been published.2g CAUTION. Al-
though we have not experienced any problems, alkyl azides
should be treated as potential explosion hazards. Except
where noted, all reagents were obtained commercially.
3-Azid o-1-p r op a n ol (2a ). To 70 mL of DMF was added
3-bromo-1-propanol (10 g, 72 mmol). Sodium azide (19 g, 290
mmol) was added slowly. The mixture was stirred vigorously
at room temperature for 10.5 h at which time 200 mL of Et2O
was added. The organic layer was washed with H2O (50 mL)
and brine (50 mL). The aqueous layer was extracted with Et2O
(5 × 50 mL). The organic layer was dried over Na2SO4,
filtered, and concentrated at 1 atm. The crude product was
purified by column chromatography (1:1 f 3:1 Et2O/pentane)
Finally, we note that the reaction was problematic
when reactions with R,â-unsaturated aldehydes were
attempted. We presume that the availability of ad-
ditional electrophilic sites in the aldehyde results in

2486 J . Org. Chem., Vol. 61, No. 7, 1996
Badiang and Aube´
to afford 7.0 g of 2 (96%):6 1H NMR (300 MHz, CDCl3) δ 1.78
(pentet, J ) 6.0 Hz, 2H), 2.37 (br s, 1H), 3.39 (t, J ) 6.0 Hz,
2H), 3.68 (t, J ) 6.0 Hz, 2H); 13C NMR (74.5 MHz, CDCl3) δ
2-Ben zyl-5-p h en yloxa zolin e (8c): 158 mg, 80% yield; Rf
0.4 (1:1 hexane/EtOAc); 1H NMR (300 MHz, CDCl3) δ 3.71 (s,
2H), 3.74-3.82 (m, 1H), 4.13 (dd, J ) 6.9, 7.2 Hz, 1H), 4.27
(dd, J ) 3.9, 10.2 Hz, 1H), 5.47 (dd, J ) 2.4, 7.8 Hz, 1H), 7.17-
7.39 (m, 10H); 13C NMR (74.5 MHz, CDCl3) δ 35.4, 63.1, 73.2,
81.5, 126.0, 127.5, 128.6, 129.2, 129.6, 135.3, 141.4, 167.0; IR
(NaCl) 3400, 1660, 1485, 1445, 1230, 1150 cm-1; MS (FAB),
m/ z 238 (M+ + H), 120, 91; HRMS calcd for C16H16NO
238.1232 (M+ + H), found 238.1231.
2-(p-Nitr op h en yl)-5-p h en yloxa zolin e (9c): 80 mg, 80%
yield; Rf 0.3 (3:1 pentane/Et2O); mp 143-145 °C; 1H NMR (300
MHz, CDCl3) δ 4.20 (dd, J ) 7.2, 8.1 Hz, 1H), 4.54 (dd, J )
5.1, 10.2 Hz, 1H), 5.73 (dd, J ) 2.1, 8.1 Hz, 1H), 7.34-7.55
(m, 5H), 8.24 (AB q, ∆ν ) 30.4 Hz, J ) 9.0 Hz, 4H); 13C NMR
(74.5 MHz, CDCl3) δ 63.7, 82.2, 124.0, 126.2, 129.0, 129.3,
129.7, 133.8, 140.7, 150.0, 162.6; IR (NaCl, CHCl3) 3400, 1640,
1590, 1520, 1330 cm-1; MS (FAB), m/ z 269 (M+ + H), 253,
150, 135, 120, 104, 91; HRMS calcd for C15H13N2O3 269.0926
(M+ + H), found 269.0934.
31.8, 48.8, 60.0; IR (NaCl, CCl4) 3400, 2940, 2085, 1250 cm-1
.
Gen er a l P r oced u r e for th e P r ep a r a tion of 2-Su bsti-
tu ted -5,6-d ih yd r o-4H-1,3-oxa zin es a n d 2-Su bstitu ted Ox-
a zolin es. A solution of aldehyde (1.0 equiv) and azide (1.1
equiv) in CH2Cl2 (0.2-0.5 M) was cooled to 0 °C followed by
dropwise addition of BF3‚OEt2 (2.0 equiv); the addition of acid
was accompanied by gas evolution. The reaction mixture was
allowed to warm to room temperature and the solution stirred
for the specified time in Table 2. Saturated NaHCO3 (ca. 25-
35 mL) was added slowly, and the solution was stirred until
bubbling ceased. The reaction mixture was extracted with
Et2O, EtOAc, or CH2Cl2 (3 × 30 mL), and the organic layer
was washed with brine, dried (Na2SO4), filtered, and concen-
trated to afford the crude product, which was purified by silica
gel chromatography.
2-n -P en tyl-5-p h en yloxa zolin e (5c): 259 mg, 79% yield;
Rf 0.4 (3:1 hexane/EtOAc); 1H NMR (300 MHz, CDCl3) δ 0.84-
0.94 (m, 3H), 1.33-1.40 (m, 4H), 1.68-1.73 (m, 2H), 2.37 (t, J
) 7.7 Hz, 2H), 3.76 (dd, J ) 6.3, 7.9 Hz, 1H), 4.24 (dd, J )
3.9, 10.2 Hz, 1H), 5.45 (dd, J ) 2.1, 8.1 Hz, 1H), 7.27-7.41
(m, 5H); 13C NMR (74.5 MHz, CDCl3) δ 14.4, 22.7, 26.1, 28.6,
31.8, 63.0, 81.0, 126.0, 128.6, 129.1, 141.6, 168.5; IR (NaCl,
CHCl3) 1660, 1485, 1445, 1425, 1220, 1160 cm-1; MS (FAB),
m/ z 218 (M+ + H), 120; HRMS calcd for C14H20NO 218.1545
(M+ + H), found 218.1551.
2-(p -Ca r b om e t h oxyp h e n yl)-5,6-d ih yd r o-4H -1,3-oxa -
zin e (10a ): 160 mg, 75% yield; Rf 0.4 (1:1 hexane/EtOAc); 1H
NMR (300 MHz, CDCl3) δ 2.00 (pentet, J ) 5.7 Hz, 2H), 3.63
(t, J ) 5.9 Hz, 2H), 3.92 (s, 3H), 4.38 (t, J ) 5.4 Hz, 2H), 7.99
(AB q, ∆ν ) 22.4 Hz, J ) 8.7 Hz, 4H); 13C NMR (74.5 MHz,
CDCl3) δ 22.4, 43.1, 52.6, 65.8, 127.4, 129.7, 132.1, 138.1, 155.3,
167.2; IR (NaCl, CHCl3) 1710, 1640, 1425, 1400, 1340, 1270,
1125, 1090 cm-1; MS (FAB), m/ z, 220 (M+ + H), 163; HRMS
+
calcd for C12H14NO3 220.0974 (M + H), found 220.0960.
2-(1,3-Ben zod ioxa n -5-yl)-5,6-d ih yd r o-4H -1,3-oxa zin e
1
(6a ): 150 mg, 73% yield; Rf 0.3 (1:1 hexane/EtOAc); H NMR
2-(p-Ca r bom eth oxyp h en yl)oxa zolin e (10b): 102 mg,
55% yield; Rf 0.4 (1:1 hexane/EtOAc); mp 130-132 °C; 1H NMR
(300 MHz, CDCl3) δ 3.93 (s, 3H), 4.09 (t, J ) 9.5 Hz, 2H), 4.46
(t, J ) 9.5 Hz, 2H), 8.04 (AB q, ∆ν ) 20.0 Hz, J ) 8.4 Hz, 4H);
13C NMR (74.5 MHz, CDCl3) δ 52.7, 55.5, 68.2, 128.5, 129.9,
132.1,132.8 164.2, 166.8; IR (NaCl, CHCl3) 1710, 1635, 1430,
1400, 1270 cm-1; MS (FAB), m/ z 206 (M+ + H), 163; HRMS
calcd for C11H13NO3 206.0817 (M+ + H), found 206.0835.
2-(p -Ca r b om et h oxyp h en yl)-5-p h en yloxa zolin e (10c):
131 mg, 82% yield; Rf 0.6 (2:1 hexane/EtOAc); mp 94-95 °C;
1H NMR (300 MHz, CDCl3) δ 3.95 (s, 3H), 4.03 (dd, J ) 6.9,
8.1 Hz, 1H), 4.52 (dd, J ) 4.8, 10.2 Hz, 1H), 5.70 (dd, J ) 1.8,
8.1 Hz, 1H), 7.34-7.43 (m, 5H), 8.07-8.13 (m, 4H); 13C NMR
(74.5 MHz, CDCl3) δ 52.7, 63.7, 81.8, 126.2, 128.7, 128.8, 129.3,
130.0, 132.1, 133.0, 141.1, 163.6; IR (NaCl, CHCl3) 3400, 1710,
1635, 1270 cm-1; MS (FAB), m/ z 282 (M+ + H), 163; HRMS
calcd for C17H16NO3 282.1130 (M+ + H), found 282.1139.
2-(p -Me t h o x y p h e n y l)-5,6-d ih y d r o -4H -1,3-o x a zin e
(11a ): 200 mg, 70% yield; Rf 0.2 (1:1 hexane/EtOAc); 1H NMR
(300 MHz, CDCl3) δ 1.92 (pentet, J ) 5.7 Hz, 2H), 3.54 (t, J )
6.0 Hz, 2H), 3.78 (s, 3H), 4.30 (t, J ) 5.4 Hz, 2H), 6.82 (d, J )
9.0 Hz, 2H), 7.79 (d, J ) 8.7 Hz, 2H); 13C NMR (74.5 MHz,
CDCl3) δ 22.1, 42.6, 55.3, 65.1, 113.3, 126.8, 128.4, 155.3, 161.4;
IR (NaCl, CHCl3) 2950, 1640, 1605, 1510, 1350, 1305, 1280,
1270, 1250 cm-1; MS (FAB), m/ z 192 (M+ + H), 135; HRMS
calcd for C11H14NO2 192.1025 (M+ + H), found 192.1033.
2-(p-Acetylp h en yl)-5,6-d ih yd r o-4H-1,3-oxa zin e (12a ):
146 mg, 73% yield; Rf 0.4 (3:1 EtOAc/hexane); mp 95-97 °C;
1H NMR (300 MHz, CDCl3) δ 4.33 (t, J ) 5.4 Hz, 2H), 3.58 (t,
J ) 5.9 Hz, 2H), 2.57 (s, 3H), 1.95 (pentet, J ) 5.7 Hz, 2H),
7.91 (AB q, ∆ν ) 10.7 Hz, J ) 9.0 Hz, 4H); 13C NMR (74.5
MHz, CDCl3) δ 22.2, 27.1, 43.1, 65.6, 127.4, 128.3, 138.5, 138.6,
155.5, 198.0; IR (NaCl, CHCl3) 1645, 1675, 1605, 1300, 1260,
1130, 1100 cm-1; MS (FAB), m/ z 204 (M+ + H), 147; HRMS
calcd for C12H14NO2 204.1025 (M+ + H), found 204.1039.
(300 MHz, CDCl3) δ 1.96 (pentet, J ) 5.7 Hz, 2H), 3.58 (t, J )
5.8 Hz, 2H), 4.33 (t, J ) 5.6 Hz, 2H), 5.97(s, 2H), 6.78 (d, J )
8.1 Hz, 1H), 7.37 (d, J ) 1.8 Hz, 1H), 7.44 (dd, J ) 8.1, 1.8 Hz,
1H); 13C NMR (74.5 MHz, CDCl3) δ 22.0, 42.6, 65.2, 101.3,
107.4, 107.6, 121.4, 147.5, 155.0; IR (NaCl, CHCl3) 3400, 1640,
1500, 1485, 1440, 1250 cm-1; MS (FAB), m/ z 206 (M+ + H),
149; HRMS calcd for C11H12NO3 206.0817(M+ + H), found
206.0804.
2-(1,3-Ben zod ioxa n -5-yl)-oxa zolin e (6b): 107 mg, 56%
yield; Rf 0.4 (1:1 hexane/EtOAc); mp 114-117 °C; 1H NMR (300
MHz, CDCl3) δ 4.03 (t, J ) 9.3 Hz, 2H), 4.40 (t, J ) 9.3 Hz,
2H), 6.02 (s, 2H), 6.83 (d, J ) 8.1 Hz, 1H), 7.41 (d, J ) 1.2 Hz,
1H), 7.50 (dd, J ) 6.9, 1.2 Hz, 1H); 13C NMR (74.5 MHz, CDCl3)
δ 55.3, 68.0, 101.9, 108.4, 108.7, 122.2, 123.5, 148.0, 150.6,
164.6; IR (NaCl, CHCl3) 1640, 1500, 1490, 1450, 1255 cm-1
;
MS (FAB), m/ z 192 (M+ + H), 149; HRMS calcd for C10H10
-
NO3 192.0661 (M+ + H), found 192.0663.
2-(1,3-Ben zod ioxa n -5-yl)-5-p h en yloxa zolin e (6c): 50
mg, 37% yield; Rf 0.5 (1:1 pentane/Et2O); 1H NMR (300 MHz,
CDCl3) δ 3.96 (dd, J ) 6.6, 7.8 Hz, 2H), 4.45 (dd, J ) 4.5, 10.2
Hz, 1H), 5.64 (dd, J ) 1.8, 8.0 Hz, 1H), 6.03 (s, 2H), 6.85 (d, J
) 8.1 Hz, 1H), 7.33-7.41 (m, 5H), 7.49 (s, 1H), 7.58 (d, J )
8.4 Hz, 1H); 13C NMR (74.5 MHz, CDCl3) δ 63.6, 81.5, 102.0,
108.5, 108.9, 122.1, 123.7, 126.1, 128.7, 129.2, 141.5, 148.1,
150.7, 164.0; IR (NaCl, CHCl3) 1640, 1495, 1480, 1440, 1250
cm-1; MS (FAB), m/ z 268 (M+ + H), 149, 91; HRMS calcd for
C16H14NO3 268.0974 (M+ + H), found 268.0984.
2-ter t-Bu tyl-5-p h en yloxa zolin e (7c): 123 mg, 69% yield;
Rf 0.4 (1:1 hexane/EtOAc); 1H NMR (300 MHz, CDCl3) δ 1.30
(s, 9H), 3.75 (dd, J ) 6.3, 7.8 Hz, 1H), 4.26 (dd, J ) 4.2, 10.2
Hz, 1H), 5.45 (dd, J ) 2.4, 7.8 Hz, 1H), 7.26-7.41 (m, 5H); 13
C
NMR (74.5 MHz, CDCl3) δ 28.2, 33.7, 63.3, 81.0, 125.9, 128.5,
129.2, 142.1, 174.5; IR (NaCl) 3400, 1650, 1490, 1470, 1450,
1255 cm-1; MS (FAB), m/ z 204 (M+ + H), 146, 120; HRMS
calcd for C13H18NO 204.1388 (M+ + H), found 204.1404.
2-Ben zyl-5,6-d ih yd r o-4H-1,3-oxa zin e (8a ): 148 mg, 70%
yield; Rf 0.4 (5% MeOH/CHCl3); 1H NMR (300 MHz, CDCl3) δ
1.84 (pentet, J ) 5.7 Hz, 2H), 3.39 (t, J ) 5.9 Hz, 2H), 3.45 (s,
2H), 4.13 (t, J ) 5.6 Hz, 2H), 7.22-7.36 (m, 5H); 13C NMR
(74.5 MHz, CDCl3) δ 22.0, 42.7, 43.0, 65.5, 127.0, 128.8, 129.3,
137.1, 159.5; IR (NaCl, CHCl3) 3400, 1660, 1490, 1350, 1240,
1080 cm-1; MS (FAB), m/ z 176 (M+ + H), 91; HRMS calcd for
C11H14NO 176.1075 (M+ + H), found 176.1071.
(7) Levy, A.; Litt, M. J . Polym. Sci., Part B: Polym. Phys. 1967, 5,
881-886.
(8) Wenker, H. J . Am. Chem. Soc. 1938, 60, 2152-2155.
(9) Pridgen, L. N.; Killmer, L. B.; Webb, R. L. J . Org. Chem. 1982,
47, 1985-1989.
(10) Levy, A.; Bassiri, T. G.; Litt, M. J . Polym. Sci., Part B: Polym.
Phys. 1967, 5, 871-879.
(11) Wagner-J auregg, T.; Roth, M. Chem. Ber. 1960, 93, 3036-3047.
(12) Elfeldt, P. Chem. Ber. 1891, 24, 3218-3228.
(13) Leffler, M. T.; Adams, R. J . Am. Chem. Soc. 1937, 59, 2252-
2258.
(6) Carrie´, R.; Carboni, B.; Vaultier, M. Tetrahedron 1987, 43, 1799-
1180.

Conversion of Aldehydes to Oxazolines and Dihydrooxazines
J . Org. Chem., Vol. 61, No. 7, 1996 2487
2-(p-Acetylp h en yl)oxa zolin e (12b): 80 mg, 42% yield; Rf
0.3 (3:1 EtOAc/hexane); mp 102-105 °C; 1H NMR (300 MHz,
CDCl3) δ 2.55 (s, 3H), 4.01 (t, J ) 9.3 Hz, 2H), 4.38 (t, J ) 9.6
Hz, 2H), 7.96 (AB q, ∆ν ) 12.0 Hz, J ) 9.0 Hz, 4H); 13C NMR
(74.5 MHz, CDCl3) δ 27.2, 55.5, 68.2, 128.6, 132.2, 139.4, 164.2,
Ack n ow led gm en t. This work was supported by the
National Institutes of Health. J .A. is an Alfred P. Sloan
Fellow and an American Cyanamid Faculty Awardee.
197.9; IR (NaCl, CHCl3) 1680, 1640, 1610, 1355, 1260 cm-1
;
MS (FAB), m/ z 190 (M+ + H), 147; HRMS calcd for C11H12
-
Su p p or tin g In for m a tion Ava ila ble: Synthetic proce-
dures and characterization data for p-acetaldehyde, 1, 2b, and
NO2 190.0868 (M+ + H), found 190.0855.
1
3 and copies of H and 13C NMR spectra for compounds 2b,
Syn th esis of Kn ow n Dih yd r ooxa zin es a n d Oxa zolin es.
The following known compounds were prepared as described
as above: 4a ,7 4b,8 4c,9 5a ,10 5b,7 7a ,8,11 7b,7 8b,12 9a ,13 9b,13,14
and 11b.14,15
5c, 6a , 6b, 6c, 7c, 8a , 8c, 9c, 10a , 10b, 10c, 11a , 12a , 12b,
and 13a (35 pages). This material is contained in libraries
on microfiche, immediately follows this article in the microfilm
version of the journal, and can be ordered from the ACS; see
any current masthead page for ordering information.
(14) Kwiatkowski, M.; Sund, C.; Ylikoski, J . Synthesis 1987, 9, 853-
854.
J O9521256
(15) Rehlander, P. Chem. Ber. 1894, 27, 2154-2161.