Chemoselective removal of acyloxy in 1-(benzotriazole-1-yl)alkyl esters and its application in the preparation of β-(benzotriazole-1-yl)alcohols

Article abstract of DOI:10.1080/00397910801993735

Mediated by samarium diiodide, 1-(benzotriazole-1-yl)alkyl esters 1 underwent cross-coupling with aldehydes or ketones to afford β-(benzotriazole-1-yl)alcohols 2 exclusively with the selective removal of acyloxy over benzotriazolyl. Copyright Taylor & Fra

Full text of DOI:10.1080/00397910801993735

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Chemoselective Removal of
Acyloxy in 1-(Benzotriazole-1-
yl)alkyl Esters and Its
Application in the Preparation
of β-(Benzotriazole-1-
yl)alcohols
Xiaoxia Wang a , Hui Mao a , Guanqun Xie a
Jingxing Du a
&
a Zhejiang Key Laboratory for Reactive Chemistry
on Solid Surfaces, College of Chemistry and Life
Sciences , Zhejiang Normal University , Jinhua,
China
Published online: 28 Aug 2008.
To cite this article: Xiaoxia Wang , Hui Mao , Guanqun Xie & Jingxing Du (2008)
Chemoselective Removal of Acyloxy in 1-(Benzotriazole-1-yl)alkyl Esters and
Its Application in the Preparation of β-(Benzotriazole-1-yl)alcohols, Synthetic
Communications: An International Journal for Rapid Communication of Synthetic
Organic Chemistry, 38:17, 2908-2918, DOI: 10.1080/00397910801993735
To link to this article: http://dx.doi.org/10.1080/00397910801993735
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Synthetic Communications1, 38: 2908–2918, 2008
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910801993735
Chemoselective Removal of Acyloxy in
1-(Benzotriazole-1-yl)alkyl Esters and
Its Application in the Preparation of
b-(Benzotriazole-1-yl)alcohols
Xiaoxia Wang, Hui Mao, Guanqun Xie, and Jingxing Du
Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, College of
Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, China
Abstract: Mediated by samarium diiodide, 1-(benzotriazole-1-yl)alkyl esters 1
underwent cross-coupling with aldehydes or ketones to afford b-(benzotriazole-1-yl)-
alcohols 2 exclusively with the selective removal of acyloxy over benzotriazolyl.
Keywords: 1-(Benzotriazole-1-yl)alkyl esters, carbonyl compounds, chemoselec-
tive reduction, cross-coupling, samarium diiodide
Bifunctional derivatives in which two leaving groups with different
reactivity attach to the same carbon (containing X-C-Y structure, where
X, Y is the leaving group) constitute a class of useful substrates for the
construction of multifunctional groups based on selective elimination
of one of the leaving groups. The breaking of either the C-X or C-Y bond
can usually be distinguished by a reducing agent. For example, the
reductive cleavage of the C-halogen bond occurred preferably over the
C-P bond when a-haloalkylphosphonates were treated with Bu3SnH.[1]
The Br-C-OAc structure underwent a reductive cleavage of the C-Br
bond and underwent cross-coupling with ketones by treatment with
SmI2-HMPA.[2] Reductive lithiation of a-aminosulfides R2N-C-SPh
could afford nonstabilized a-aminocarbanions with the sulfenyl group
Received December 23, 2007.
Address correspondence to Xiaoxia Wang, Zhejiang Key Laboratory for
Reactive Chemistry on Solid Surfaces, College of Chemistry and Life Sciences,
Zhejiang Normal University, Jinhua 321004, China. E-mail: wangxiaoxia@
zjnu.cn
2908

Chemoselective Removal of Acyloxy
2909
being cleaved first.[3a] The selective removal of the sulfenyl has also been
observed in the reduction of O,S-acetals[3b] (RO-C-SPh) by SmI2 in
benzene–HMPA solution with t-BuOH as an additive.
Compounds with a benzotriazolyl group (Bt) attached to an
a-heteroatom carbon no doubt constitute a fairly considerable part of such
building blocks (Bt-C-X, X ¼ halogen, NR2, alkoxy [OR], sulfenyl [SR],
etc.).[4] Likewise, the C-Bt bond could be selectively cleaved and used for
different synthetic purposes. SmI2 causes the C-Bt bond cleavage in N-
[(N,N-dialkylamino)-alkyl]-benzotriazoles (Bt-C-NR2) to form a variety
of compounds such as tertiary vicinal diamines,[5a] N-cycloalkylamines,[5b]
and 1,2-amino alcohols.[5c] We previously reported the cleavage of C-Bt
bonds in N-(a-benzotriazol-1-ylalkyl)amides (Bt-C-NHCOR) and N-(a-
benzotriazol-1-ylalkyl)sulfonamides (Bt-C-NHTs) to synthesize vicinal
diamides, vicinal disulfamides, and a-hydroxyalkylated sulfonamides.[6]
Herein we report the chemoselective reduction of Bt-C-OCOR
compounds [1-(benzotriazole-1-yl)alkyl esters 1] and their cross-coupling
with carbonyl compounds. It should be noted that compounds 1 contain
two good leaving groups, namely the acyloxy and benzotriazolyl groups.
The selective elimination of either of the leaving groups from the bifunc-
tional derivatives followed by a cross-coupling with carbonyl compounds
can provide a useful protocol for the construction of b-heteroatom-
substituted alcohols via hydroxyalkylation.[7]
Thus, a mixture of 1 and a carbonyl compound (aldehyde or ketone)
was added simultaneously to a SmI2-THF solution at room temperature
with an expectation to produce two kinds of coupling products corres-
ponding to the two cleavage pathways (Scheme 1). Path A involves the
Scheme 1. Two possible pathways for the reductive coupling of 1 with carbonyl
compounds.

2910
X. Wang et al.
reductive cleavage of the acyloxy by SmI2, and the resulting radical A
then attacks the carbonyl or ketyl[8] to give product 2, whereas in path
B the benzotriazolyl was cleaved to produce radical B, which coupled
with carbonyl or ketyl to afford compound 3.
Surprisingly, though the benzotriazolyl moiety in the Bt-C-OCOR
compounds could be selectively substituted by an alkyl, alkenyl, or aryl
group in organozinc reagents to afford carboxylic esters,[9] exclusive
removal of the acyloxy was observed (only path A was followed) under
the reductive conditions here. Correspondingly, the corresponding
cross-coupling products b-(benzotriazole-1-yl)alcohols 2 were obtained
in good to excellent yields. The results are listed in Table 1. The type
of product 3 was not detected in all the cases of the reductive coupling
reaction, indicating path B was not followed at all.
As can be summarized from Table 1, both aliphatic aldehydes and
ketones underwent the reductive coupling smoothly. Diphenylmethanone
also gave satisfactory yields (Table 1, entries 6 and 12). Aromatic alde-
hyde such as benzaldehyde mainly afforded pinacols as in the other
cross-coupling reaction.[7a] Generally, the yields of the cross-coupling
products resulting from ketones were higher than those from aldehydes.
The lower efficiency of the coupling involving aldehydes may result
from the side reactions such as simple reduction and pinacol coupling,
to which the aldehydes were prone.[11]
Under the reaction conditions, the removal of the acyloxy over the
benzotriazolyl group was always observed, no matter if R1 was an alkyl
or aryl. Theoretically, an electron-withdrawing group (such as chloro)
present in R1 could facilitate the leaving tendency of the corresponding
acyloxy (Table 1, entries 12 and 13); however, the electron-donating
group (methoxy) at the aryl in the acyloxy moiety does not diminish
the leaving ability to a remarkable extent (Table 1, entries 7–11).
R2 can be an alkyl or aryl and therefore broaden the scope for the syn-
thesis of compounds 2. Although b-(benzotriazole-1-yl)alcohols with the
structure BtꢀCH2ꢀC(OH)R1R2 could be smoothly prepared,[7i,j] their
homologues with a substituent at the methylene carbon could not be
obtained because of the limited substrates (BtꢀCH2ꢀX). The Katritzky
group reported the preparation of such compounds from N-allyl- or N-ben-
zyl benzotriazoles by treatment with n-butyllithium at ꢀ78 ꢁC followed by
the nucleophilic attack on aldehydes and ketones.[12] However, the com-
pounds with common substituents other than benzyl and allyl remained
unexplored, to which difficult lithiation may be ascribed. Therefore, the
cross-coupling between easily available 1-(benzotriazole-1-yl)alkyl esters
1 and carbonyl compounds mediated by SmI2 provides a general and highly
efficient method for the preparation of a variety of b-(benzotriazole-1-yl)
alcohols though the diastereoselectivities are not satisfactory at this stage.

2911

2912

Chemoselective Removal of Acyloxy
2913
In summary, mediated by SmI2 in THF at room temperature, the
reductive elimination of acyloxy over benzotriazolyl in a variety of
1-(benzotriazole-1-yl)alkyl esters occurred preferentially in the cross-
coupling reaction with carbonyl compounds. Good yields of a variety
of b-(benzotriazole-1-yl)alcohols can be prepared this way.
It was reported that different additives could alter the reductive
removal sequence of sulfenyl and alkoxy in monothioacetals[3b] with
SmI2 as the reducing agent. With the potential good leaving ability of
benzotriazolyl,[13] the possibility of reversing the reductive removal
sequence of acyloxy and benzotriazoyl in 1-(benzotriazole-1-yl)alkyl
esters is worth exploring further.
EXPERIMENTAL
Tetrahydrofuran was distilled from sodium benzophenone immediately
prior to use. Melting points are uncorrected. 1H NMR (400-MHz) spectra
were recorded on a Bruker AV400 NMR instrument as CDCl3 solutions
using TMS as internal standard. Chemical shifts (d) are reported in parts
permillion(ppm)andcouplingconstantsJaregiveninhertz. IRspectrawere
recorded in film or using KBr disks with a Nicolet Nexus 670 FT-IR
spectrometer. Massspectra were recordedon anHP 5989B MSspectrometer
(70 eV). Elemental analyses were performed on a Vario-ELIII instrument.
General Procedure for the Reductive Tandem Deacyloxy and
Cross-Coupling Reaction
1-(Benzotriazole-1-yl)alkyl esters 1 (1 mmol) dissolved in dry THF
(10 mL) were added at room temperature to 2.2 mmol of SmI2 dissolved
in THF (20 mL) under nitrogen. The resulting solution turned yellow in
0.5–1 h. Dilute hydrochloric acid (0.5 M, 5 mL) was added, and the result-
ing mixture was extracted with diethyl ether (3 ꢂ 20 mL). The combined
organic layer was washed with brine, dried over anhydrous sodium sul-
fate, and concentrated under reduced pressure to give a residue, which
was purified by column chromatography on silica gel with ethyl acetate
and cyclohexane (1:6) as eluent to afford the b-(benzotriazole-1-yl)
alcohols 2.
DATA
Compound 1a: colorless oil. nmax(film)=cmꢀ1: 2971, 2939, 2819, 1748
1
=
=
(C O), 1614 (N N). H NMR (400 MHz, CDCl3): d 8.08 (1H, d, J

2914
X. Wang et al.
8.4 Hz), 7.79 (1H, d, J 8.4 Hz), 7.54 (1H, t, J 7.6 Hz), 7.40 (1H, t, J
7.6 Hz), 7.22 (1H, t, J 7.2 Hz, CH), 2.50–2.58 (2H, m, CH2), 2.28–2.38
(2H, m, CH2), 1.59–1.64 (2H, m, CH2), 0.97 (3H, t, J 7.2 Hz, CH3),
0.88 (3H, t, J 7.2 Hz, CH3); 13C NMR (100 MHz, CDCl3): d 172.3
=
(C O), 145.9, 132.5, 127.9, 124.3, 120.0, 110.3, 80.5, 35.7, 26.5, 18.1,
13.4, 9.2. Anal. calcd. for C13H17N3O2: C, 63.14; H, 6.93; N, 16.99.
Found: C, 62.98; H, 6.95; N, 16.93%.
Compound 2a: colorless oil. nmax(film)=cmꢀ1: 3390 (OH), 2975, 2834,
1
=
1614 (N N), 1453, 747. H NMR (400 MHz, CDCl3): d 7.88 (d, J 8.0 Hz,
1H), 7.57 (d, J 8.0 Hz, 1H), 7.36 (t, J 8.0 Hz, 1H), 7.24 (t, J 7.6 Hz, 1H),
4.43 (dd, J 2.8, 12 Hz, 1H), 3.52 (br, s, 1H), 2.38–2.43 (m, 1H), 2.07–2.13
(m, 1H), 1.26 (s, 3H), 1.06 (s, 3H), 0.53 (t, J 7.2 Hz, 3H); 13C NMR
(100 MHz, CDCl3): d 145.1, 134.8, 127.3, 124.0, 119.6, 110.5, 71.3,
70.6, 29.2, 27.5, 22.1, 11.0. m=z (%): 221 (Mþ þ 2, 1.3), 161 (100), 132
(81.6), 104 (71.9), 77 (49.8), 59 (82.5). Anal. calcd. for C12H17N3O: C,
65.73; H, 7.81; N, 19.16. Found: C, 65.87; H, 7.80; N, 19.27%.
Compound 2b: colorless oil. nmax(film)=cmꢀ1: 3396 (OH), 3062,
2971, 2881, 1615 (N N), 1453, 747. 1H NMR (400 MHz, CDCl3): d
=
7.88 (d, J 8.4 Hz, 1H), 7.63 (d, J 8.4 Hz, 1H), 7.32 (t, J 8.0 Hz, 1H),
7.20 (t, J 7.6 Hz, 1H), 4.59 (dd, J 3.2, 12 Hz, 1H), 3.41 (br, s, 1H),
2.34–2.37 (m, 1H), 1.97–2.02 (m, 1H), 1.60–1.71 (m, 2H), 1.04–1.08 (m,
1H), 0.95–0.98 (m, 1H), 0.83 (t, J 7.2 Hz, 3H), 0.66 (t, J 7.6 Hz, 3H),
0.44 (t, J 7.6 Hz, 3H); 13C NMR (100 MHz, CDCl3): d 145.3, 134.4,
127.3, 123.9, 119.6, 111.0, 77.0, 67.6, 28.2, 27.3, 21.4, 10.8, 7.9, 7.5.
m=z (%): 248 (Mþ þ 1, 2.5), 161 (100), 146 (75.0), 132 (50.3), 104
(31.7), 87 (28.3), 77 (27.9). Anal. calcd. for C14H21N3O: C, 67.98; H,
8.56; N, 16.99. Found: C, 67.85; H, 8.58; N, 17.05%.
Compound 2c: colorless oil. nmax(film)=cmꢀ1: 3361 (OH), 2932,
1
=
2857, 1620 (N N), 1453, 744. Major: H NMR (400 MHz, CDCl3): d
7.94 (d, J 8.0 Hz, 1H), 7.24–7.40 (m, 8H) 5.57 (d, J 8.0 Hz, 1H), 4.96–
4.96 (m, 1H), 3.97 (br, s, 1H), 1.39–1.53 (m, 2H), 1.22–1.26 (m, 2H),
1
0.87 (t, J 7.2 Hz, 3H). Minor: H NMR (400 MHz, CDCl3): d 7.94 (d,
J 8.0 Hz, 1H), 7.24–7.40 (m, 8H), 5.57 (d, J 8.0 Hz, 1H), 4.96–4.96 (m,
1H), 3.97 (br, s, 1H), 1.86–1.87 (m, 1H), 1.65–1.70 (m, 1H), 1.39–1.53
(m, 2H), 1.22–1.26 (m, 3H). m=z (%): 281 (Mþ, 2.3), 208 (29.9), 180
(100), 91 (13.1), 77 (15.4). Anal. calcd. for C17H19N3O: C, 72.57; H,
6.81; N, 14.94. Found: C, 72.66; H, 6.83; N, 14.89%.
Compound 2d: colorless oil. nmax(film)=cmꢀ1: 3405 (OH), 2953,
1
=
2863, 1615 (N N), 1445, 742. Major: H NMR (400 MHz, CDCl3): d
8.10–8.12 (m, 1H), 7.59–7.62 (m, 1H), 7.47–7.53 (m, 1H), 7.40 (t, J
8.0 Hz, 1H), 4.50–4.56 (m, 1H), 2.49–2.53 (m, 1H), 2.16–2.19 (m, 1H),
1.70–1.75 (m, 1H), 1.25 (q, J 7.2 Hz, 1H), 1.01 (t, J 7.2 Hz, 3H),
0.96 (s, 3H), 0.65 (t, J 7.2 Hz, 3H). Minor: 1H NMR (400 MHz,

Chemoselective Removal of Acyloxy
2915
CDCl3): d 8.10–8.12 (m, 1H), 7.59–7.62 (m, 1H), 7.47–7.53 (m, 1H),
7.40 (t, J 8.0 Hz, 1H), 4.50–4.56 (m, 1H), 2.49–2.53 (m, 1H), 2.16–
2.19 (m, 1H), 1.70–1.75 (m, 1H), 1.36 (s, 3H), 1.25 (q, J 7.2 Hz, 1H),
0.87 (s, 3H), 0.65 (t, J 7.2 Hz, 3H). m=z (%): 233 (Mþ, 1.3), 218
(1.8), 161 (100), 146 (73.5), 132 (69.2), 104 (49.8), 77 (34.7), 73 (53.8).
Anal. calcd. for C13H19N3O: C, 66.92; H, 8.21; N, 18.01. Found: C,
66.81; H, 8.19; N, 18.05%.
Compound 2e: colorless oil. nmax(film)=cmꢀ1: 3402, 2963, 2875, 1623
1
=
(N N), 1448, 745. H NMR (400 MHz, CDCl3): d 8.09–8.14 (m, 3H),
7.74–7.77 (m, 3H), 7.55–7.65 (m, 2H), 7.42–7.51 (m, 6H), 5.77 (dd, J
6.4, 8.8 Hz, 1H), 2.81–2.89 (m, 1H), 2.53–2.61 (m, 1H), 0.93 (t, J
7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3): d 146.1, 143.6, 137.5, 137.2,
133.5, 132.7, 130.7, 130.1, 128.45, 128.40, 127.5, 126.8, 124.4, 120.1,
109.7, 65.1, 28.1, 11.3. m=z (%): 343 (Mþ, 1.0), 183 (71.8), 161 (100),
146 (63.7), 132 (45.3), 104 (43.6), 77 (38.1). Anal. calcd. for
C22H21N3O: C, 76.94; H, 6.16; N, 12.24. Found: C, 76.86; H, 6.15; N,
12.30%.
Compound 2f: white solid, mp 147–149 ꢁC. nmax(film)=cmꢀ1: 3457
1
=
(OH), 2975, 1614 (N N), 1452, 741. H NMR (400 MHz, CDCl3): d
8.07 (d, J 8.0 Hz, 1H), 7.51 (d, J 8.0 Hz, 2H), 7.36–7.44 (m, 2H), 7.30–
7.36 (m, 4H), 5.54 (s, 1H), 4.22 (s, 1H, OH), 1.36 (s, 3H), 1.32 (s, 3H).
13C NMR (100 MHz, CDCl3): 145.0, 135.8, 133.8, 128.9, 128.5, 128.4,
127.8, 124.4, 120.1, 109.6, 73.5, 71.4, 28.7, 27.3. m=z (%): 252
(Mþ ꢀ 15, 1.2), 209 (35.7), 180 (100), 104 (20.8), 77 (14.3), 59 (22.8).
Anal. calcd. for C16H17N3O: C, 71.89; H, 6.41; N, 15.72. Found: C,
72.01; H, 6.38; N, 15.67%.
Compound 2g: colorless oil. nmax(film)=cmꢀ1: 3450 (OH), 2971,
1
=
1621 (N N), 1442, 748. Major: H NMR (400 MHz, CDCl3): d 7.96
(d, J 8.4 Hz, 1H), 7.28–7.41 (m, 8H), 5.49–5.52 (m, 1H), 5.09–5.16
1
(m, 1H), 1.26 (d, J 6.0 Hz, 3H). Minor: H NMR (400 MHz, CDCl3):
d 8.03 (d, J 8.4 Hz, 1H), 7.28–7.41 (m, 8H), 5.49–5.52 (m, 1H), 5.09–
5.16 (m, 1H), 1.26 (d, J 6.0 Hz, 3H). m=z (%): 253 (Mþ, 0.9), 209
(35.8), 180 (100), 152 (24.1), 104 (21.9), 91 (6.7), 77 (16.4). Anal. calcd.
for C15H15N3O: C, 71.13; H, 5.97; N, 16.59. Found: C, 71.22; H, 5.99;
N, 16.55%.
Compound 2h: colorless oil. nmax(film)=cmꢀ1: 3461 (OH), 2953, 1619
1
=
(N N), 1450, 743. Major: H NMR (400 MHz, CDCl3): d 7.96 (d, J
8.0 Hz, 1H), 7.14–7.34 (m, 5H), 7.10–7.12 (m, 2H), 5.45–5.48 (m, 1H),
5.07–5.13 (m, 1H), 3.50 (s, 1H, OH), 2.29 (s, 3H), 1.23 (d, J 6.4 Hz,
3H). Minor: 1H NMR (400 MHz, CDCl3): d 8.05 (d, J 8.0 Hz, 1H),
7.14–7.34 (m, 5H), 7.10–7.12 (m, 2H), 5.45–5.48 (m, 1H), 5.07–5.13 (m,
1H), 3.90 (s, 1H, OH), 2.29 (s, 3H), 1.23 (d, J 6.4 Hz, 3H). m=z (%):
269 (Mþ þ 2, 1.5), 223 (100), 194 (77.3), 180 (65.8), 118 (26.1), 104

2916
X. Wang et al.
(19.5), 77 (14.6). Anal. calcd. for C16H17N3O: C, 71.89; H, 6.41; N, 15.72.
Found: C, 71.84; H, 6.38; N, 15.75%.
Compound 2i: colorless oil. nmax(film)=cmꢀ1: 3441 (OH), 2979, 2930,
1
=
1627 (N N), 1452, 744. H NMR (400 MHz, CDCl3): d 8.03 (d, J 8.4 Hz,
1H), 7.32–7.47 (m, 5H), 7.10 (d, J 8.0 Hz, 2H), 5.57 (s, 1H), 4.30 (s, 1H,
OH), 2.27 (s, 3H), 1.35 (s, 3H), 1.33 (s, 3H). m=z (%): 281 (Mþ, 2.5), 223
(100), 194 (74.1), 180 (69.0), 118 (24.8), 104 (21.6), 77 (17.2). Anal. calcd.
for C17H19N3O: C, 72.57; H, 6.81; N, 14.94. Found: C, 72.53; H, 6.84; N,
14.88%.
Compound 2j: colorless oil. nmax(film)=cmꢀ1: 3492 (OH), 2969, 2941,
1
=
1613 (N N), 1452, 745. H NMR (400 MHz, CDCl3): d 8.03 (d, J 8.0 Hz,
1H), 7.58 (d, J 8.0 Hz, 1H), 7.51 (d, J 8.0 Hz, 1H), 7.30–7.45 (m, 2H),
7.09–7.17 (m, 3H), 5.68 (s, 1H), 4.30 (s, 1H, OH), 2.25 (s, 3H), 1.42–
1.58 (m, 4H), 0.93–0.97 (m, 3H), 0.82 (t, J 7.2 Hz, 3H). m=z (%): 309
(Mþ, 2.1), 252 (4.2), 223 (100), 194 (68.3), 180 (53.1), 118 (28.4), 104
(21.6), 87 (11.4), 77 (9.6). Anal. calcd. for C19H23N3O: C, 73.76; H,
7.49; N, 13.58. Found: C, 73.70; H, 7.45; N, 13.61%.
Compound 2k: colorless oil. nmax(film)=cmꢀ1: 3408 (OH), 2965,
2929, 1659 (N N), 1450, 743. 1H NMR (400 MHz, CDCl3): d 8.07
=
(d, J 8.4 Hz, 1H), 7.75 (t, J 8.4 Hz, 4H), 7.65 (d, J 8.4 Hz, 2H), 7.54–
7.57 (m, 2H), 7.43–7.48 (m, 4H), 7.36 (t, J 7.6 Hz, 1H), 5.33 (d, J
10.4 Hz, 1H), 3.25–3.31 (m, 1H), 1.02 (d, J 6.8 Hz, 3H), 0.95 (d, J
6.4 Hz, 3H); 13C NMR (100 MHz, CDCl3): d 145.8, 142.7, 137.6,
137.2, 133.3, 132.6, 130.5, 130.0, 128.3, 127.8, 127.4, 124.0, 120.1,
109.3, 70.4, 32.9, 20.4, 20.3. m=z (%): 357 (Mþ, 0.7), 183 (47.6), 161
(100), 146 (61.3), 132 (57.1), 104 (49.6), 77 (36.5). Anal. calcd. for
C23H23N3O: C, 77.28; H, 6.49; N, 11.76. Found: C, 77.35; H, 6.46;
N, 11.79%.
Compound 2l: colorless oil. nmax(film)=cmꢀ1: 3404 (OH), 2956, 2864,
1
=
1619 (N N), 1451, 743. H NMR (400 MHz, CDCl3): d 8.11 (d, J 8.4 Hz,
1H), 7.50–7.56 (m, 2H), 7.41 (t, J 8.4 Hz, 1H), 4.41 (d, J 4.8 Hz, 1H),
2.76–2.84 (m, 1H), 1.03 (s, 3H), 0.97–0.99 (m, 6H); 13C NMR
(100 MHz, CDCl3): d 144.6, 135.3, 127.8, 124.2, 120.0, 109.8, 74.1,
71.8, 29.8, 28.7, 27.6, 23.0, 18.9. m=z (%): 234 (Mþ þ 1, 1.7), 161 (100),
146 (70.2), 132 (56.1), 104 (45.7), 77 (41.9). Anal. calcd. for
C13H19N3O: C, 66.92; H, 8.21; N, 18.01. Found: C, 66.87; H, 8.25; N,
18.05%.
ACKNOWLEDGMENTS
We are grateful to the Natural Science Foundation of Zhejiang Province
(Project No. Y405035) for financial support.

Chemoselective Removal of Acyloxy
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