Reductive hydroxyalkylation/alkylation of amines with lactones/esters

Article abstract of DOI:10.1039/c2ob25901j

We have developed a one-pot method for the direct intermolecular reductive hydroxyalkylation or alkylation of amines using lactones or esters as the hydroxyalkylating/alkylating reagents. The method is based on the in situ amidation of lactones/esters with DIBAL-H-amine complex (for primary amines) or DIBAL-H-amine hydrochloride salt complex (for secondary amines), followed by reduction of the amides with an excess of DIBAL-H. Different from the reduction of Weinreb amides with DIBAL-H where aldehydes are formed, the reduction of the in situ formed Weinreb amides yielded amines. Moreover, this method is not limited to Weinreb amides, instead, it also works for other amides in general. A plausible mechanism is suggested to account for the outcome of the reactions.

Full text of DOI:10.1039/c2ob25901j

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PAPER
Reductive hydroxyalkylation/alkylation of amines with lactones/esters†
Yu-Huang Wang,a Jian-Liang Ye,a Ai-E Wanga and Pei-Qiang Huang*a,b
Received 10th May 2012, Accepted 14th June 2012
DOI: 10.1039/c2ob25901j
We have developed a one-pot method for the direct intermolecular reductive hydroxyalkylation or
alkylation of amines using lactones or esters as the hydroxyalkylating/alkylating reagents. The method is
based on the in situ amidation of lactones/esters with DIBAL-H–amine complex (for primary amines) or
DIBAL-H–amine hydrochloride salt complex (for secondary amines), followed by reduction of the
amides with an excess of DIBAL-H. Different from the reduction of Weinreb amides with DIBAL-H
where aldehydes are formed, the reduction of the in situ formed Weinreb amides yielded amines.
Moreover, this method is not limited to Weinreb amides, instead, it also works for other amides in
general. A plausible mechanism is suggested to account for the outcome of the reactions.
Introduction
Amines are an important class of compounds in organic chem-
istry, which constitute a major body of natural products (alka-
loids) and pharmaceutical agents.1 For the preparation of higher
order amines, the monoalkylation of primary or secondary
amines with halides is a logic but problematic method2,3 due to
the well-known over-alkylation (Scheme 1, route A).2a As a
result, many indirect methods4 have been developed for the
monoalkylation of amines, which include the classic Gabriel
synthesis of primary amines,5 alkylation involving N-protection
and deprotection,6 addition to imines,7 reductive amination of
Scheme 1 Typical known (routes A to C) and Present (route D) syn-
aldehydes or ketones (Scheme 1, route B),8 and reduction9 or
thetic approaches to secondary and tertiary amines.
reductive alkylation of amides (Scheme 1, route C).10 On the
other hand, lactones and esters are a class of stable, easily avail-
able and environmentally friendly starting materials.11,12 Their
Results and discussion
uses for amines synthesis are usually related to stepwise pro-
cedures.13 Only a single instance of one-step synthesis14 has
The investigation stemmed from the amide synthesis developed
from our laboratory, namely, the amidation of lactones/esters
with DIBAL-H–amine complex or DIBAL-H–amine hydrochlo-
ride salt complex.19 The reductive hydroxyalkylation of benzyl-
amine with lactone 1a was selected as a model reaction and the
results are outlined in Table 1. The optimal protocol was ident-
ified as successive treatment of lactone 1a with 1.1 equiv of
DIBAL-H–benzylamine complex in THF at rt, and 5.0 equiv of
DIBAL-H at rt (Table 1, entry 4).
With the optimal reaction conditions defined, the reductive
alkylations of amines with other lactones were investigated. As
outlined in Table 2, the reductive alkylation of primary amines
with different lactones gave the corresponding hydroxyalkylated
secondary amines in good yields (entries 1–8). For the reductive
hydroxyalkylation of allylamine, portion-wise addition of 8.0
equiv of DIBAL-H with prolonged reaction time (48 h) was
necessary to ensure a decent yield (Table 2, entries 9, 10). For
the reductive alkylation of secondary amines, use of its
been reported, which involved a low-yield (<35%) intramolecu-
lar reductive alkylation of lactam-ester.14a In continuation with
our endeavor3b,10a,b,15 to develop step-economical synthetic
methods,16 a one-pot synthesis17 of hydroxyalkylated amines/
amines by reductive (hydroxy)alkylation of amines with lac-
tones/esters (Scheme 1, route D) was undertaken. We now report
the results of this investigation. It is worth noting that hydro-
xyalkyl carbinamines constitutes a group of multi-functionalized
compounds of multi-uses.8b,18
aDepartment of Chemistry, College of Chemistry and Chemical
Engineering, Xiamen University, Xiamen, Fujian 361005, P.R. China.
E-mail: pqhuang@xmu.edu.cn; Fax: +86-592-2186400
bThe State Key Laboratory of Elemento-Organic Chemistry, Nankai
University, Tianjin 300071, P.R. China
†Electronic supplementary information (ESI) available: 1H and 13C
NMR spectra of all new compounds. See DOI: 10.1039/c2ob25901j
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Table 1 Investigation on the conditions for the reductive
4-hydroxybutylation of benzylamine with γ-butyrolactone
DIBAL-H produced complex D, which after workup, gave
amine product eventually.
Conclusions
In summary, a one-pot method for the intermolecular reductive
hydroxyalkylation/alkylation of amines using lactones/esters as
the hydroxyalkylating/alkylating reagents has been developed.
This method can be used for direct synthesis of either secondary
or tertiary amines depending on the starting amines used. More-
over, in view of the current interest in the direct reductive alkyl-
ation of amides,10 the capture of the presumed in situ formed
iminium ion intermediate C (Scheme 2) by a carbon-centered
nucleophile would led to a C–C bond formation, and provide a
direct method for the synthesis of sec-alkylcarbinamines from
amines and lactones/esters.
% Yielda
Entry
DIBAL-H (equiv)
Temp. (°C)
Time (h)
2a
3a
1
2
3
4
5
3.2
3.2
4
5
5
0
rt
rt
rt
5
—
54
76
90
87
—
32
9
0
0
24
24
3
50
1
a Isolated yield.
Experimental section
General method
hydrochloride salt–DIBAL-H complex was essential in the ami-
dation step,19 and the subsequent reduction reaction proceeded
smoothly to give the corresponding tertiary amines (entries
11–14). Remarkably, in contrast with the reaction of the Weinreb
amides and DIBAL-H, which gave aldehydes as the reduction
products,20 reaction of the Weinreb amides, generated in situ
from lactones 1a/1c and DIBAL-H–N-methyl-N-methoxyamine
hydrochloride salt complex, yielded the reductive hydroxyalky-
lated amines (entries 13, 14).
In view of future application of this method for the synthesis
of natural products, the reaction with chiral and commercially
unavailable lactones was envisioned. Among a number of
methods available for the synthesis of lactones,11,12 the SmI2-
mediated21 one-pot reductive coupling of a ketone with an
α,β-unsaturated ester was a straightforward and versatile one.22
Lactone 1-oxaspiro[4.5]decan-2-one (1e) was thus synthesized
by SmI2-mediated one-pot reductive coupling22b of cyclohexa-
none with methyl acrylate (76% yield), and subjected to the reac-
tion with benzylamine to give the desired hydroxyalkylated
amine 2o in 78% yield (entry 15). The reductive hydroxyalkyla-
tion of benzylamine with (R)-β-methyl-γ-butyrolactone (1f), a
chiron easily available from degeneration of Tigogenin,23 led to
hydroxyalkylated amine (R)-2p in 83% yield (entry 16).
This one-pot method can also be applied to the reductive
alkylation of amines with esters. As can be seen from entries 17,
18 (Table 2), reductive alkylation of primary or secondary
amines gave smoothly the corresponding secondary or tertiary
amines in comparable yields. The reaction of diethylamine with
enantiomerically pure ester 1h, another chiron easily available in
kilogram scale,24 produced the desired amine 2s in 58% yield
(entry 19). Finally, reductive alkylation of benzylamine with
ester 1i produced the amine 2t in 60% yield (entry 20).
A plausible mechanism for the one-pot reductive alkylation of
amines with lactones/esters is suggested in Scheme 2. The carbo-
nyl group of the in situ formed amide chelates with two mol-
ecules of DIBAL-H to form intermediate A, which undergoes an
intramolecular hydride delivery to yield intermediate B. Inter-
mediate B is prone to N-lone pair assisted elimination to generate
an iminium species C. Reduction of C with a third molecule of
Melting points were uncorrected. HRFABMS spectra were
recorded on a 7.0T FT-MS instrument. H NMR and 13C NMR
1
spectra were recorded on a Bruker Avance III spectrometer at
400 and 100 MHz, respectively. Chemical shifts (δ) are reported
in ppm and referenced to residual solvent or solvent signals
(CDCl3, 7.26 ppm for H NMR and 77.0 ppm for 13C NMR;
1
CD3CN, 1.94 ppm for H NMR and 118.3 ppm for 13C NMR).
1
Silica gel (300–400 mesh) was used for flash column chromato-
graphy, eluting (unless otherwise stated) with ethyl acetate–
hexane mixture. THF was distilled over sodium benzophenone
ketyl under N2.
Typical procedure for the reductive hydroxyalkylation/alkylation
of amines using lactones/esters
Under a nitrogen atmosphere, to a solution of γ-butyrolactone 1a
(0.076 mL, 1.0 mmol) in THF (3.5 mL) was added
DIBAL-H·H2NBn complex (1.1 mmol), prepared19 from
DIBAL-H (1 M in hexane, 1.1 mL, 1.1 mmol) and benzylamine
(0.12 mL, 1.1 mmol) in THF (0.4 mL) at rt. After being stirred
for 30 min, the mixture was cooled to 0 °C, and DIBAL-H
(1.0 M in hexane, 5.0 mL, 5.0 mmol) was added dropwise. The
resulting mixture was stirred at rt. After a complete conversion
of the amide intermediate as indicated by TLC monitoring (3 h),
the reaction was quenched carefully with MeOH (0.5 mL) at
0 °C, and diluted with THF (10 mL). To the mixture was added
5 mL of a saturated aqueous solution of potassium sodium tar-
trate and stirred vigorously for 3 h before being extracted with
Et2O (10 mL × 3). The combined organic layers were washed
with brine, dried over Na2SO4, filtered and concentrated under
reduced pressure. The residue was purified by flash column
chromatography on silica gel (eluent: CH2Cl2–MeOH = 10 : 1
containing 1% ammonia) to give 4-hydroxybutylamine 2a25a
(162 mg, 90%).
N-Benzyl-4-hydroxybutan-1-amine (2a). Colorless oil. ν/cm−1
(film) 3292, 3062, 3028, 2931, 2858, 1645, 1603, 1547, 1495,
1453, 1037, 1058, 1029, 738, 699. δH (400 MHz, CDCl3)
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Table 2 Reductive ω-hydroxyalkylation/alkylation of amines with ω-lactones/esters
Entry
1
Ester
4/Temp./time (equiv/°C/h)
DIBAL-H/temp./time (equiv/°C/h)
5/rt/3
Product 2a (%Yield)
1.1/rt/0.5
2
3
1.1/rt/0.5
1.1/rt/0.5
5/rt/4
7/rt/6
4
5
2.5/rt/0.5
2.5/rt/0.5
5/rt/23
5/rt/24
6
7
8
2.5/rt/0.5
2.5/rt/0.5
2.5/rt/0.5
6/rt/20
6/rt/17
6/rt/17
9
2.5/rt/0.5
2.5/rt/0.5
8/rt/48
8/rt/48
10
11
12
13
2/rt/0.5
2/rt/0.5
2/rt/0.5
5/rt/1
5/rt/1
4/0/0.5
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Table 2 (Contd.)
Entry
14
Ester
4/Temp./time (equiv/°C/h)
DIBAL-H/temp./time (equiv/°C/h)
4/0/0.5
Product 2a (%Yield)
2/rt/0.5
15
1.5/rt/0.5
6/rt/5
16
17
1.2/rt/0.5
5/50/2
5/rt/5
6/rt/48
18
5/50/2
5/rt/1
19
20
5/rt/2
6/rt/5
2/rt/0.5
6/rt/48
a Isolated yield. b Yield of the amide intermediate 3. c Yield of side product 1,6-hexanediol 6.
1.68–1.56 (4H, m, CH2), 2.65 (2H, t, J = 5.8 Hz, NCH2), 3.55
(2H, s br, OH and NH), 3.56 (2H, t, J = 6.8 Hz, OCH2), 3.75
(2H, s, NCH2Ph), 7.34–7.21 (5H, m, Ph). δC (100 MHz,
CDCl3), 27.9 (CH2), 31.8 (CH2), 49.0 (NCH2), 53.6 (NCH2Ph),
62.2 (OCH2), 127.0, 128.1, 128.3, 139.2. MS (ESI, m/z): 180
(M + H+). HRMS (ESI, m/z) [M + H+] Calculated for
C11H18NO2+ 180.1383, found: 180.1378.
(CH2), 33.5 (CH2CO), 43.5 (NCH2Ph), 61.9 (CH2OH), 127.3,
127.6, 128.6, 138.1, 173.6 (CO). MS (ESI, m/z): 216 (M + Na+).
N-Benzyl-5-hydroxypentan-1-amine
(2b). Following
the
typical procedure, the reaction of the amide generated in situ
from ω-valerolactone 1b (0.095 mL, 1.0 mmol) and
DIBAL-H·H2NBn (1.1 mmol), with DIBAL-H (1.0 M in
hexane, 5.0 mL, 5.0 mmol) produced, after flash column chrom-
atography (eluent: CH2Cl2–MeOH = 10 : 1, v/v, containing 1%
aqueous ammonia), 2b25b (177 mg, 92%) as a colorless oil.
ν/cm−1 (film) 3350, 3062, 3028, 2931, 2857, 1643, 1602, 1548,
1495, 1453, 1383, 1075, 1054, 745, 699. δH (400 MHz, CDCl3)
1.41–1.33 (2H, m, CH2), 1.52 (4H, pentet, J = 7.1 Hz,
CH2CH2), 2.61 (2H, t, J = 7.1 Hz, NCH2), 2.78 (2H, s br, OH
and NH), 3.55 (2H, t, J = 6.4 Hz, OCH2), 3.76 (2H, s,
N-Benzyl-4-hydroxybutanamide (3a).19 White solid. mp
73–74 °C. ν/cm−1 (film) 3297, 3085, 2921, 2871, 1640, 1549,
1453, 1422, 1379, 1275, 1059, 1015, 731, 696. δH (400 MHz,
CDCl3) 1.81 (2H, pentet, J = 6.2 Hz, CH2), 2.31 (2H, t, J =
6.9 Hz, CH2CO), 3.59 (2H, dd, J = 10.4, 5.4 Hz, CH2O), 3.74
(1H, t, J = 4.7 Hz, OH), 4.35 (2H, d, J = 5.7 Hz, NCH2Ph), 6.69
(1H, s br, NH), 7.32–7.20 (5H, m). δC (100 MHz, CDCl3) 28.1
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N-Butyl-5-hydroxypentan-1-amine (2e). Following the typical
procedure, the reaction of the amide generated in situ from
ω-valerolactone 1b (0.095 mL, 1.0 mmol) and DIBAL-
H·H2Nn-Bu (2.5 mmol), with DIBAL-H (1.0 M in hexane,
5.0 mL, 5.0 mmol) produced, after flash column chromatography
(eluent: CH2Cl2–MeOH = 10 : 1, v/v, containing 1% aqueous
ammonia), 2e25e (135 mg, 85%) as a colorless oil. ν/cm−1 (film)
3372, 3286, 2931, 2860, 1634, 1537, 1466, 1414, 1377, 1307,
1117, 1058. δH (400 MHz, CDCl3) 0.85 (3H, t, J = 7.3 Hz,
CH3), 1.53–1.21 (10H, m, CH2CH2), 2.52 (4H, app. q, J = 7.0 Hz,
NCH2), 2.71 (2H, s br, OH and NH), 3.50 (2H, t, J = 6.5 Hz,
OCH2). δC (100 MHz, CDCl3) 13.8 (CH3), 20.3 (CH2), 23.4
(CH2), 29.4 (CH2), 31.9 (CH2), 32.4 (CH2), 49.5 (NCH2), 49.6
(NCH2), 61.8 (OCH2). MS (ESI, m/z): 160 (M + H+). HRMS
(ESI, m/z) [M + H+] Calculated for C9H22NO+ 160.1696, found:
160.1694.
Scheme 2 Plausible mechanism for the one-pot reductive alkylation of
amines with lactones/esters.
N-(4-Hydroxybutyl)-3-methylbutan-1-amine (2f). Following
the typical procedure, the reaction of the amide generated in situ
from γ-butyrolactone 1a (0.076 mL, 1.0 mmol) and
DIBAL-H·H2NCH2CH2CH(CH3)2 (2.5 mmol), with DIBAL-H
(1.0 M in hexane, 6.0 mL, 6.0 mmol) produced, after flash
column chromatography (eluent: CH2Cl2–MeOH = 10 : 1, v/v,
containing 1% aqueous ammonia), 2f (116 mg, 73%) as a color-
less oil. ν/cm−1 (film) 3383, 3289, 2955, 2929, 1870, 1644,
1537, 1469, 1416, 1382, 1367, 1307, 1115, 1071. δH (400 MHz,
CDCl3) 0.85 (6H, d, J = 6.6 Hz, CH3), 1.35 (2H, app. q, J = 7.4 Hz,
CH2), 1.66–1.54 (5H, m, CH2CH2 and CHMe2), 2.63–2.56
(4H, m, NCH2), 3.52 (2H, t, J = 4.8 Hz, OCH2), 3.70 (2H, s br,
OH and NH). δC (100 MHz, CDCl3) 22.5 (Me), 26.0 (CHMe2),
28.7 (CH2), 32.5 (CH2), 38.7 (CH2), 47.6 (NCH2), 49.7 (NCH2),
62.4 (OCH2). MS (ESI, m/z): 160 (M + H+). HRMS (ESI, m/z)
Calculated for [M + H+] C9H22NO+ 160.1695, found: 160.1696.
NCH2Ph), 7.32–7.21 (5H, m, Ph). δC (100 MHz, CDCl3) 23.3
(CH2), 29.3 (CH2), 32.3 (CH2), 48.9 (NCH2Ph), 53.7 (NCH2),
61.9 (OCH2), 126.9, 128.1, 128.3, 139.6. MS (ESI, m/z): 194
(M + H+). HRMS (ESI, m/z) [M + H+] Calculated for
C12H20NO+ 194.1539, found: 194.1533.
N-Benzyl-6-hydroxyhexan-1-amine (2c). Following the typical
procedure, the reaction of the amide generated in situ from
ε-caprolactone 1c (0.110 mL, 1.0 mmol) and DIBAL-H·H2NBn
(1.1 mmol), with DIBAL-H (1.0 M in hexane, 7.0 mL,
7.0 mmol) produced, after flash column chromatography (eluent:
CH2Cl2–MeOH = 10 : 1, v/v, containing 1% aqueous ammonia),
2c25c (179 mg, 87%) as a colorless oil. ν/cm−1 (film) 3295,
3062, 3027, 2929, 2855, 1642, 1603, 1581, 1495, 1454, 1380,
1058, 737, 699. δH (400 MHz, CDCl3) 1.36–1.29 (4H, m,
CH2CH2), 1.51 (4H, app. pentet, J = 7.1 Hz, CH2CH2), 2.60
(2H, t, J = 7.3 Hz, NCH2), 2.87 (2H, s br, OH and NH), 3.53
(2H, t, J = 6.6 Hz, OCH2), 3.76 (2H, s, NCH2Ph), 7.31–7.20
(5H, m, Ph). δC (100 MHz, CDCl3) 25.5 (CH2), 26.9 (CH2),
29.5 (CH2), 32.5 (CH2), 48.9 (NCH2), 53.6 (NCH2Ph), 62.0
(OCH2), 126.8, 128.0, 128.2, 139.5. MS (ESI, m/z): 208 (M +
H+). HRMS (ESI, m/z) [M + H+] Calculated for C13H22NO+
208.1696, found: 208.1696.
4-Hydroxy-N-isopropylbutan-1-amine (2g). Following the
typical procedure, the reaction of the amide generated in situ
from γ-butyrolactone 1a (0.076 mL, 1.0 mmol) and DIBAL-
H·i-PrNH2 (2.5 mmol), with DIBAL-H (1.0 M in hexane,
6.0 mL, 6.0 mmol) produced, after flash column chromatography
(eluent: CH2Cl2–MeOH = 10 : 1, v/v, containing 1% aqueous
ammonia), 2g25f (107 mg, 81%) as a colorless oil. ν/cm−1 (film)
3363, 3277, 2965, 2933, 2865, 1644, 1470, 1383, 1364, 1339,
1175, 1134, 1060. δH (400 MHz, CDCl3) 1.05 (6H, d, J = 6.3 Hz,
Me), 1.67–1.59 (4H, m, CH2CH2), 2.60 (2H, t, J = 5.8 Hz,
NCH2), 2.77 (1H, septet, J = 6.3 Hz, NCH), 3.44 (2H, s br, OH
and NH), 3.53 (2H, t, J = 4.9 Hz, OCH2). δC (100 MHz, CDCl3)
22.5 (Me), 29.1 (CH2), 32.4 (CH2), 46.9 (NCH2), 48.7 (NCH),
62.3 (OCH2). MS (ESI, m/z): 132 (M + H+). HRMS (ESI, m/z)
[M + H+] Calculated for C7H18NO+ 132.1383, found: 132.1390.
N-Butyl-4-hydroxybutan-1-amine (2d). Following the typical
procedure, the reaction of the amide generated in situ from
γ-butyrolactone 1a (0.076 mL, 1.0 mmol) and DIBAL-H·H2Nn-
Bu (2.5 mmol), with DIBAL-H (1.0 M in hexane, 5.0 mL,
5.0 mmol) produced, after flash column chromatography (eluent:
CH2Cl2–MeOH = 10 : 1, v/v, containing 1% aqueous ammonia),
2d25d (120 mg, 83%) as a colorless oil. ν/cm−1 (film) 3372,
3286, 2956, 2931, 2871, 1644, 1537, 1466, 1416, 1377, 1309,
1116, 1072. δH (400 MHz, CDCl3) 0.83 (3H, t, J = 7.3 Hz,
CH3), 1.26 (2H, sextet, J = 6.9 Hz, CH2), 1.41 (2H, pentet, J =
6.9 Hz, CH2), 1.62–1.50 (4H, m, CH2CH2), 2.54 (2H, t, J = 7.3 Hz,
NCH2), 2.57 (2H, t, J = 5.6 Hz, NCH2), 3.48 (2H, t, J = 4.9 Hz,
OCH2), 4.00 (2H, s br, OH and NH). δC (100 MHz, CDCl3)
13.7 (CH3), 20.2 (CH2), 28.2 (CH2), 31.5 (CH2), 32.1 (CH2),
49.0 (NCH2), 49.4 (NCH2), 62.2 (OCH2). MS (ESI, m/z): 146
(M + H+). HRMS (ESI, m/z) [M + H+] Calculated for
C8H20NO+ 146.1539, found: 146.1542.
4-Hydroxy-N-isopropylpentan-1-amine (2h). Following the
typical procedure, the reaction of the amide generated in situ
from γ-valerolactone 1d (0.095 mL, 1.0 mmol) and
DIBAL-H·H2Ni-Pr (2.5 mmol), with DIBAL-H (1.0 M in
hexane, 6.0 mL, 6.0 mmol) produced, after flash column chrom-
atography (eluent: CH2Cl2–MeOH = 10 : 1, v/v, containing 1%
aqueous ammonia), 2h25g (109 mg, 75%) as a colorless oil.
ν/cm−1 (film) 3367, 3277, 2966, 2929, 2868, 1647, 1469, 1383,
1370, 1339, 1174, 1126, 1090. δH (400 MHz, CDCl3) 1.03 (3H,
d, J = 6.3 Hz, NCHMe), 1.04 (3H, d, J = 6.3 Hz, NCHMe), 1.12
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N-Allyl-5-hydroxypentanamide (3c).25i White solid. mp
68–70 °C. ν/cm−1 (film) 3293, 3083, 2930, 2867, 1641, 1548,
1422, 1384, 1261, 1158, 1058, 988, 921. δH (400 MHz, CDCl3)
1.55 (2H, app. dt, J = 14.1, 6.1 Hz, CH2), 1.70 (2H, pentet, J =
7.3 Hz, CH2), 2.22 (2H, t, J = 7.3 Hz, CH2CO), 3.19 (1H, s br,
OH), 3.59 (2H, t, J = 5.8 Hz, OCH2), 3.82 (2H, app. tt, J = 5.7,
1.4 Hz, NCH2), 5.06–5.18 (2H, m,vCH2), 5.73–5.85 (1H,
m,vCH), 6.26 (1H, s br, NH). δC (100 MHz, CDCl3) 21.8
(CH2), 31.8 (CH2), 35.9 (CH2CO), 41.8 (NCH2), 61.7 (OCH2),
116.2 (vCH2), 134.2 (vCH), 173.3 (CO). MS (ESI, m/z) 180
(M + Na+).
(3H, d, J = 6.0 Hz, OCHMe), 1.46–1.31 (2H, m, CH2),
1.78–1.60 (2H, m, CH2), 2.51–2.43 (1H, m, NCH), 2.78–2.71
(2H, m, NCH2), 3.71–3.62 (1H, m, OCH), 3.79 (2H, s br, OH
and NH). δC (100 MHz, CDCl3) 22.2 (NCHMe), 22.6
(NCHMe), 23.6 (OCHMe), 27.8 (CH2), 39.0 (CH2), 47.1
(NCH), 48.7 (NCH2), 67.2 (OCH). MS (ESI, m/z): 146 (M +
H+). HRMS (ESI, m/z) [M + H+] Calculated for C8H20NO+
146.1539, found: 146.1541.
N-Allyl-4-hydroxybutAN-1-amine (2i). Following the typical
procedure, the reaction of the amide generated in situ from
γ-butyrolactone
1a
(0.076
mL,
1.0
mmol)
and
N,N-Diethyl-4-hydroxybutan-1-amine (2k). Following the
typical procedure, the reaction of the amide generated in situ
from γ-butyrolactone 1a (0.076 mL, 1.0 mmol) and
DIBAL-H·HNEt2·HCl (2 mmol), with DIBAL-H (1.0 M in
hexane, 5.0 mL, 5.0 mmol) produced, after flash column chrom-
atography (eluent: CH2Cl2–MeOH = 10 : 1, v/v, containing 1%
aqueous ammonia), 2k25j (103 mg, 71%) as a colorless oil.
ν/cm−1 (film) 3388, 2970, 2935, 2872, 2817, 1653, 1469, 1382,
1293, 1199, 1065. δH (400 MHz, CDCl3) 1.00 (6H, t, J = 7.2
Hz, Me), 1.63–1.59 (4H, m, CH2CH2), 2.39–2.36 (2H, m,
NCH2), 2.51 (4H, q, J = 7.2 Hz, NCH2Me), 3.52–3.49 (2H, m,
OCH2). δC (100 MHz, CDCl3) 10.6 (Me), 26.3 (CH2), 32.7
(CH2), 46.1 (NCH2Me), 53.3 (NCH2), 62.5 (OCH2). MS (ESI,
m/z): 146 (M + H+). HRMS (ESI, m/z) [M + H+] Calculated for
C8H20NO+ 146.1539, found: 146.1541.
DIBAL-H·H2NCH3CHvCH2 (2.5 mmol), with DIBAL-H
(1.0 M in hexane, 8.0 mL, 8.0 mmol) produced, after flash
column chromatography (eluent: CH2Cl2–MeOH = 10 : 1, v/v,
containing 1% aqueous ammonia), 2i25h (93 mg, 72%), along
with 13% of the amide intermediate 3b. 2i: yellow oil. ν/cm−1
(film) 3372, 3288, 3078, 2933, 2862, 1644, 1548, 1453, 1377,
1187, 1108, 1060, 996, 919. δH (400 MHz, CDCl3) 1.62–1.51
(4H, m, CH2CH2), 2.58 (2H, t, J = 5.9 Hz, NCH2), 3.18 (2H,
app. dt, J = 6.1, 1.3 Hz, NCH2CHv), 3.50 (2H, t, J = 6.7 Hz,
OCH2), 3.50 (2H, s br, OH and NH), 5.04 (1H, ddd, J = 10.2,
2.7, 1.2 Hz, CHv), 5.11 (1H, ddd, J = 17.2, 3.2, 1.6 Hz,v
CH2), 5.82 (1H, ddt, J = 16.4, 10.2, 6.1 Hz,vCH2). δC
(100 MHz, CDCl3) 28.0 (CH2), 31.9 (CH2), 48.8 (NCH2), 51.8
(NCH2CHv), 62.2 (OCH2), 116.4 (vCH2), 135.8 (vCH). MS
(ESI, m/z): 130 (M + H+). HRMS (ESI, m/z) [M + H+] Calcu-
lated for C7H16NO+ 130.1226, found: 130.1234.
N,N-Diethyl-4-hydroxypentan-1-amine (2l). Following the
typical procedure, the reaction of the amide generated in situ
from γ-valerolactone 1b (0.095 mL, 1.0 mmol) and
DIBAL-H·HNEt2·HCl (2 mmol), with DIBAL-H (1.0 M in
hexane, 5.0 mL, 5.0 mmol) produced, after flash column chrom-
atography (eluent: CH2Cl2–MeOH = 10 : 1, v/v, containing 1%
aqueous ammonia), 2l25k (108 mg, 68%) as a colorless oil.
ν/cm−1 (film) 3408, 2975, 2938, 2798, 1648, 1475, 1385, 1190,
1122, 1058. δH (400 MHz, CDCl3) 1.02 (6H, t, J = 7.2 Hz,
CH2Me), 1.13 (3H, d, J = 6.2 Hz, CHMe), 1.39–1.29 (1H, m,
CH2), 1.77–1.52 (3H, m, CH2), 2.50–2.36 (4H, m, NCH2Me),
2.66–2.57 (2H, m, NCH2), 3.71–3.63 (1H, m, OCH). δC
(100 MHz, CDCl3) 10.6 (CH2Me), 23.8 (CH2), 24.9 (CHMe),
39.5 (CH2), 46.0 (NCH2Me), 53.7 (NCH2), 67.3 (OCH). MS
(ESI, m/z) 160 (M + H+). HRMS (ESI, m/z) [M + H+] Calculated
for C8H20NO+ 160.1696, found: 160.1699.
N-Allyl-4-hydroxybutanamide (3b).25i White solid. mp
72–74 °C. δH (400 MHz, CDCl3) 1.83 (2H, app. pentet, J = 6.4
Hz, CH2), 2.33 (2H, t, J = 7.0 Hz, CH2CO), 3.62 (2H, t, J = 5.8
Hz, NCH2), 3.69 (1H, s br, OH), 3.81 (2H, app. t, J = 5.6 Hz,
OCH2), 5.06–5.18 (2H, m,vCH2), 5.84–5.72 (1H, m,vCH),
6.57 (1H, s br, NH). δC (100 MHz, CDCl3) 28.2 (CH2), 33.5
(CH2CO), 41.9 (NCH2), 61.8 (OCH2), 116.2 (vCH2), 134.0
(vCH), 173.6 (CO). ν/cm−1 (film) 3299, 3086, 2924, 2872,
1650, 1642, 1552, 1421, 1384, 1261, 1058, 922. MS (ESI, m/z)
166 (M + Na+).
N-Allyl-5-hydroxypentan-1-amine (2j). Following the typical
procedure, the reaction of the amide generated in situ from
ω-valerolactone
1b
(0.095
mL,
1.0
mmol)
and
DIBAL-H·H2NCH3CHvCH2 (2.5 mmol), with DIBAL-H
(1.0 M in hexane, 8.0 mL, 8.0 mmol) produced, after flash
column chromatography (eluent: CH2Cl2–MeOH = 10 : 1, v/v,
containing 1% aqueous ammonia), 2j (97 mg, 67%), along with
8% of the amide intermediate 3c. 2j: yellow oil. ν/cm−1 (film)
3293, 3083, 2930, 2867, 1641, 1548, 1421, 1383, 1262, 1158,
1056, 988, 920. δH (400 MHz, CDCl3) 1.37–1.32 (2H, m, CH2),
1.47 (4H, app. septet, J = 7.1 Hz, CH2CH2), 2.53 (2H, t, J = 7.1
Hz, NCH2), 2.57 (2H, s br, OH and NH), 3.16 (2H, app. dt, J =
6.1, 1.6 Hz, NCH2CHv), 3.51 (2H, t, J = 6.5 Hz, OCH2), 5.02
(1H, ddd, J = 10.2, 2.6, 1.1 Hz,vCH2), 5.09 (1H, ddd, J = 17.2,
3.2, 1.5 Hz,vCH2), 5.82 (1H, ddt, J = 16.4, 10.2, 6.1 Hz, CH).
δC (100 MHz, CDCl3) 23.4 (CH2), 29.4 (CH2), 32.4 (CH2), 49.0
(NCH2), 52.2 (NCH2CHv), 61.8 (OCH2), 116.0 (vCH2),
136.3 (vCH). MS (ESI, m/z): 144 (M + H+). HRMS (ESI, m/z)
[M + H+] Calculated for C8H18NO+ 144.1383, found: 144.1385.
4-Hydroxy-N-methoxy-N-methylbutan-1-amine (2m). Follow-
ing the typical procedure, the reaction of the amide generated in
situ from γ-butyrolactone 1a (0.076 mL, 1.0 mmol) and
DIBAL-H·HN(OCH3)CH3·HCl (2 mmol), with DIBAL-H
(1.0 M in hexane, 4.0 mL, 4.0 mmol) produced, after flash
column chromatography (eluent: EtOAc–hexane = 5 : 1, v/v),
2m (91 mg, 68%) as a colorless oil. ν/cm−1 (film) 3400, 2941,
2871, 1462, 1383, 1049, 998. δH (400 MHz, CDCl3) 1.62 (4H,
s, CH2CH2), 2.54 (3H, s, NMe), 2.62 (2H, s br, NCH2), 3.50
(3H, s, OMe), 3.59 (2H, t, J = 5.5 Hz, OCH2). δC (100 MHz,
CDCl3) 24.7 (CH2), 31.4 (CH2), 44.7 (NMe), 59.6 (OMe), 60.6
(OCH2), 62.6 (NCH2). MS (ESI, m/z) 156 (M + Na+). HRMS
+
(ESI, m/z) [M + Na+] Calculated for C6H15NNaO2 156.0995,
found: 156.0997.
This journal is © The Royal Society of Chemistry 2012
Org. Biomol. Chem., 2012, 10, 6504–6511 | 6509

View Article Online
6-Hydroxy-N-methoxy-N-methylhexan-1-amine (2n). Follow-
ing the typical procedure, the reaction of the amide generated in
situ from ε-caprolactone 1c (0.110 mL, 1.0 mmol) and
DIBAL-H·HN(OCH3)CH3·HCl (2 mmol), with DIBAL-H (1.0 M
in hexane, 4.0 mL, 4.0 mmol) produced, after flash column
N-Benzyl-2-phenylethanamine (2q). Following the typical
procedure, the reaction of the amide generated in situ from ethyl
2-phenylacetate 1g (164 mg, 1.0 mmol) and DIBAL-H·H2NBn
(5 mmol), with DIBAL-H (1.0 M in hexane, 6.0 mL, 6.0 mmol)
produced, after flash column chromatography (eluent: CH2Cl2–
MeOH = 50 : 1, v/v, containing 1% aqueous ammonia), 2q25l
(161 mg, 76%), along with 10% of the amide intermediate 3d.
2q: colorless oil. ν/cm−1 (film) 3331, 3061, 3026, 2924, 2849,
1661, 1602, 1584, 1495, 1453, 1359, 1118, 1029, 737, 698. δH
(400 MHz, CDCl3) 1.55 (1H, s br, NH), 2.83 (2H, t, J = 6.6 Hz,
CH2Ph), 2.90 (2H, t, J = 6.6 Hz, NCH2), 3.80 (2H, s, NCH2Ph),
7.34–7.17 (10H, m, Ph). δC (100 MHz, CDCl3) 36.3 (CH2Ph),
50.5 (NCH2), 53.8 (NCH2Ph), 126.1, 126.9, 128.1, 128.4 (2C),
128.7, 140.0, 140.2. MS (ESI, m/z) 212 (M + H+). HRMS (ESI,
m/z) [M + H+] Calculated for C12H20NO+ 212.1434, found:
212.1439.
chromatography (eluent: EtOAc–hexane
= 5 : 1, v/v), 2n
(106 mg, 66%), along with 22% of the 1,6-hexanediol 6. 2n:
colorless oil. ν/cm−1 (film) 3369, 2936, 2859, 1647, 1464, 1441,
1379, 1049. δH (400 MHz, CDCl3) 1.28–1.38 (4H, m, CH2CH2)
1.56–1.46 (4H, m, CH2CH2), 2.35 (1H, s br, OH), 2.50 (3H, s,
NMe), 2.54 (2H, t, J = 7.8 Hz, NCH2), 3.45 (3H, s, OMe), 3.56
(2H, t, J = 6.6 Hz, OCH2). δC (100 MHz, CDCl3) 25.3 (CH2),
25.6 (CH2), 27.1 (CH2), 32.5 (CH2), 45.1 (NMe), 59.9 (OMe),
60.7 (OCH2), 62.5 (NCH2). MS (ESI, m/z) 162 (M + H+).
+
HRMS (ESI, m/z) [M + H+] Calculated for C8H20NO2
162.1489, found: 162.1488.
N-Benzyl-2-phenylacetamide (3d).25m White solid. mp 118–
119 °C. ν/cm−1 (film) 3289, 3083, 3031, 2924, 1640, 1600,
1584, 1552, 1492, 1453, 1432, 1366, 1259, 1081, 1029, 727,
694. δH (400 MHz, CDCl3) 3.59 (2H, s, CH2CO), 4.38 (2H, d, J
= 5.8 Hz, NCH2Ph), 5.87 (1H, s br, NH), 7.36–7.14 (10H, m,
Ph). δC (100 MHz, CDCl3) 43.5 (CH2CO), 43.7 (NCH2Ph),
127.3 (2C), 127.4, 128.6, 129.0, 129.4, 134.8, 138.1, 170.8
(CO). MS (ESI, m/z) 248 (M + Na+).
N-Benzyl-3-(1-hydroxycyclohexyl)pentan-1-amine (2o). 1-Oxa-
spiro[4.5]decan-2-one 1e was synthesized by SmI2-mediated
reductive coupling22b of cyclohexanone with methyl acrylate
(yield: 76%).
Following the typical procedure, the reaction of the amide
generated in situ from 1-oxaspiro[4.5]decan-2-one 1e (154 mg,
1.0 mmol) and DIBAL-H·H2NBn (1.5 mmol), with DIBAL-H
(1.0 M in hexane, 6.0 mL, 6.0 mmol) produced, after flash
column chromatography (eluent: CH2Cl2–MeOH = 10 : 1, v/v,
containing 1% aqueous ammonia), 2o (193 mg, 76%) as a color-
less oil. ν/cm−1 (film) 3389, 3081, 3062, 3027, 2930, 2855,
1602, 1494, 1452, 1261, 1105, 1028, 969, 737, 698. δH
(400 MHz, CD3CN) 1.66–1.22 (14H, m, CH2CH2), 2.58 (2H, t,
J = 6.4 Hz, NCH2), 3.30 (2H, s br, OH and NH), 3.73 (2H, s,
NCH2Ph), 7.36–7.24 (5H, m, Ph). δC (100 MHz, CD3CN) 23.2
(CH2), 24.0 (CH2), 27.0 (CH2), 38.6 (CH2), 50.7 (NCH2), 54.2
(NCH2Ph), 70.6 (C), 127.9, 129.3 (2C), 141.2. MS (ESI, m/z)
248 (M + H+). HRMS (ESI, m/z) [M + H+] Calculated for
C16H26NO+ 248.2009, found: 248.2008.
N,N-Diethyl-2-phenylethanamine (2r). Following the typical
procedure, the reaction of the amide generated in situ from ethyl
2-phenylacetate 1g (164 mg, 1.0 mmol) and DIBAL-H·H-
NEt2·HCl (5 mmol), with DIBAL-H (1.0 M in hexane, 5.0 mL,
5.0 mmol) produced, after flash column chromatography (eluent:
CH2Cl2–MeOH = 50 : 1, v/v, containing 1% aqueous ammonia),
2r25j (117 mg, 66%) as a colorless oil. ν/cm−1 (film) 3057,
3026, 2968, 2932, 2871, 2800, 1603, 1581, 1495, 1453, 1383,
1200, 1117, 1067, 741, 698. δH (400 MHz, CDCl3) 1.07 (6H, t,
J = 7.1 Hz, Me), 2.62 (4H, q, J = 7.1 Hz, CH2Me), 2.80–2.67
(4H, m, CH2CH2), 7.22–7.16 (3H, m, Ph), 7.31–7.24 (2H, m,
Ph), δC (100 MHz, CDCl3) 11.7 (Me), 33.3 (CH2Me), 46.8
(CH2Ph), 54.8 (NCH2), 125.9, 128.3, 128.6, 140.6. MS (ESI,
m/z) 178 (M + H+). HRMS (ESI, m/z) [M + H+] Calculated
for C12H20NO+ 178.1590, found: 178.1593.
(R)-N-Benzyl-4-hydroxy-3-methylbutan-1-amine
(2p). Fol-
lowing the typical procedure, the reaction of the amide generated
in situ from (R)-3-methyl-γ-butyrolactone 1f (100 mg,
1.0 mmol), easily available from degeneration of Tigogenin,23
and DIBAL-H·H2NBn complex (1.2 mmol), with DIBAL-H
(1.0 M in hexane, 5.0 mL, 5.0 mmol) produced, after flash
column chromatography (eluent: CH2Cl2–MeOH = 10 : 1, v/v,
containing 1% aqueous ammonia), 2p (159 mg, 83%) as a color-
less oil. [α]2D0 +16.2 (c 1.0 in CHCl3). ν/cm−1 (film) 3295, 3087,
3063, 3028, 2924, 2871, 1495, 1455, 1381, 1045, 744, 699. δH
(400 MHz, CDCl3) 0.87 (3H, d, J = 6.9 Hz, Me), 1.50–1.40
(1H, m, CH), 1.71–1.64 (1H, m, CH2), 1.81–1.72 (1H, m, CH2),
2.64 (1H, ddd, J = 12.5, 9.1, 3.8 Hz, NCH2), 2.86 (1H, ddd, J =
11.9, 6.4, 3.8 Hz, NCH2), 3.29 (1H, dd, J = 11.3, 8.1 Hz,
OCH2), 3.51 (1H, dd, J = 11.3, 3.6 Hz, OCH2), 3.80 (1H, d, J =
13.1 Hz, NCH2Ph), 3.81 (1H, d, J = 13.2 Hz, NCH2Ph), 4.14
(2H, s br, OH and NH), 7.34–7.26 (5H, m, Ph). δC (100 MHz,
CDCl3) 17.8 (Me), 35.6 (CH), 36.1 (CH2), 47.1 (NCH2), 53.4
(NCH2Ph), 68.0 (OCH2), 127.5, 128.5, 128.6, 137.9. MS (ESI,
m/z) 194 (M + H+). HRMS (ESI, m/z) [M + H+] Calculated for
C12H20NO+ 194.1539, found: 194.1544.
(R)-5-(Benzyloxy)-N,N-diethyl-4-methylpentan-1-amine (2s).
Following the typical procedure, the reaction of the amide gener-
ated in situ from (R)-methyl 5-(benzyloxy)-4-methylpentanoate24
1h (236 mg, 1.0 mmol) and DIBAL-H·HNEt2·HCl (5 mmol),
with DIBAL-H (1.0 M in hexane, 6.0 mL, 6.0 mmol) produced,
after flash column chromatography (eluent: CH2Cl2–MeOH =
50 : 1, v/v, containing 1% aqueous ammonia), 2s (153.0 mg,
58%) as a colorless oil. [α]2D0 +2.8 (c 1.0 in CHCl3). ν/cm−1
(film) 3087, 3064, 3029, 2967, 2931, 2871, 2796, 1494, 1453,
1376, 1201, 1095, 734, 697. δH (400 MHz, CDCl3) 0.94 (3H, d,
J = 6.8 Hz, CHMe), 1.02 (6H, t, J = 7.2 Hz, CH2Me), 1.15–1.06
(1H, m, CH), 1.55–1.36 (3H, m, CH2), 1.82–1.73 (1H, m, CH2),
2.40 (2H, ddd, J = 8.5, 6.2, 1.7 Hz, NCH2), 2.52 (4H, q, J = 7.2
Hz, NCH2Me), 3.25 (1H, dd, J = 9.1, 6.4 Hz, OCH2), 3.32 (1H,
dd, J = 9.1, 6.4 Hz, OCH2), 4.49 (1H, d, J = 12.7 Hz, OCH2Ph),
4.50 (1H, d, J = 12.7 Hz, OCH2Ph), 7.35–7.24 (5H, m). δC
(100 MHz, CDCl3) 11.5 (CH2Me), 17.1 (Me), 24.2 (CH), 31.6
(CH2), 33.4 (CH2), 46.8 (NCH2Me), 53.2 (NCH2), 73.0 (OCH2),
6510 | Org. Biomol. Chem., 2012, 10, 6504–6511
This journal is © The Royal Society of Chemistry 2012

View Article Online
(b) S.-H. Xiang, J. Xu, H.-Q. Yuan and P.-Q. Huang, Synlett, 2010,
1829–1832.
75.9 (OCH2Ph), 127.4, 127.5, 128.3, 138.7. MS (ESI, m/z) 264
(M + H+). HRMS (ESI, m/z) [M + H+] Calculated for
C17H30NO+ 264.2322, found: 264.2318.
10 (a) K.-J. Xiao, J.-M. Luo, K.-Y. Ye, Y. Wang and P.-Q. Huang, Angew.
Chem., Int. Ed., 2010, 49, 3037–3040; (b) K.-J. Xiao, Y. Wang, K.-Y. Ye
and P.-Q. Huang, Chem.–Eur. J., 2010, 16, 12792–12796;
(c) K. Shirokane, Y. Kurosaki, T. Sato and N. Chida, Angew. Chem., Int.
Ed., 2010, 49, 6369–6372; (d) G. Vincent, R. Guillot and C. Kouklovsky,
Angew. Chem., Int. Ed., 2011, 50, 1350–1353. For a mini-review, see:
(e) D. Seebach, Angew. Chem., Int. Ed., 2011, 50, 96–101.
11 For a review on the synthesis of lactones, see: Z. Paryzek and I. Skiera,
Org. Prep. Proced. Int., 2007, 39, 203–296.
12 For a review on the synthesis of esters, see: S. Alison and J. Franklin,
J. Chem. Soc., Perkin Trans. 1, 1999, 3537–3554.
N-Benzyl-4-pentenylamine (2t). Following the typical pro-
cedure, the reaction of the amide generated in situ from ethyl
4-pentenoate 1i (640 mg, 5.0 mmol) and DIBAL-H·H2NBn
(10 mmol) with DIBAL-H (1.0 M in hexane, 30.0 mL,
30.0 mmol) produced, after fractionated, 2t25n (556 mg, 60%) as
a colorless oil. ν/cm−1 (film) 3308, 3089, 3064, 3027, 2963,
2929, 2869, 1645, 1498, 1453, 1368, 1088, 998, 907, 733, 698;
δH (400 MHz, CDCl3) 1.26 (1H, s br, NH), 1.55–1.64 (2H, m,
CH2CH2NH), 2.04–2.10 (2H, m, CH2CHv), 2.61 (2H, t, J =
7.3 Hz, CH2CH2NH), 3.76 (2H, s, NHCH2Ph), 4.92–5.05 (2H,
m,vCH2), 5.79 (1H, tdd, J = 6.7, 10.2, 17.0 Hz, CH2CHv),
7.20–7.35 (5H, m, PhH); δC (100 MHz, CDCl3) 29.3 (CH2),
31.8 (CH2), 49.0 (CH2CH2NH), 54.2 (NHCH2Ph), 115.0
(CH2v), 127.3, 128.4, 128.7, 138.6 (CH2CHv), 140.3; MS
(ESI, m/z) 176 (M + H+). HRMS (ESI, m/z) [M + H+] Calculated
for C17H30NO+ 176.1434, found: 176.1442.
13 For a recent example, see: N. S. Johnson and F. O. Ayorinde, J. Am. Oil
Chem. Soc., 2011, 88, 1425–1430.
14 (a) S. Augusto, V. Rene and P. Giovanni, Ann. Chim. (Rome, Italy), 1957,
47, 1177–1184; (b) For a reductive alkylation via specially designed thio-
esters, see: Y. L. Han and M. Chorev, J. Org. Chem., 1999, 64, 1972–1978.
15 (a) R.-F. Yang and P.-Q. Huang, Chem.–Eur. J., 2010, 16, 10319–10322;
(b) S.-C. Tuo, J.-L. Ye, A.-E. Wang, S.-Y. Huang and P.-Q. Huang, Org.
Lett., 2011, 13, 5270–5273; (c) J.-C. Liao, K.-J. Xiao, X. Zheng and
P.-Q. Huang, Tetrahedron, 2012, 68, 5297–5302.
16 For a review on green synthesis, see: (a) C.-J. Li and B. M. Trost, Proc.
Natl. Acad. Sci. U. S. A., 2008, 105, 13197–13202. For a review on step
economy synthesis, see: (b) P. A. Wender, V. A. Verma, T. J. Paxton and
T. H. Pillow, Acc. Chem. Res., 2008, 41, 40–49.
17 For recent books and reviews on one-pot and tandem reactions, see:
(a) L. F. Tietze, G. Brasche and K. Gericke, Domino Reactions in
Organic Synthesis, Wiley-VCH, Weinheim, Germany, 2006;
(b) D. Enders, C. Grondal and M. R. M. Hüttl, Angew. Chem., Int. Ed.,
2007, 46, 1570–1581; (c) H. Pellissier, Tetrahedron, 2006, 62, 1619–
1665; (d) H. Pellissier, Tetrahedron, 2006, 62, 2143–2173.
18 (a) H. F. Russell, J. B. Bremner, J. Bushelle-Edghill, M. R. Lewis, S.
R. Thomas and F. Bates II, Tetrahedron Lett., 2007, 48, 1637–1639;
(b) C. Boisson, J. C. Berthet, M. Lance, M. Nierlich and M. Ephritikhine,
Chem. Commun., 1996, 2129–2130.
Acknowledgements
The authors are grateful to the NSF of China (20902075) for
financial support, and Dr W.-S. Tian and Mr H.-D. Dong for
generously providing us with (R)-3-methyl-γ-butyrolactone and
methyl (R)-5-(benzyloxy)-4-methylpentanoate. We also thank
the Natural Science Foundation of Fujian Province (2009J05037,
2011J01056), the Specialized Research Fund for the Doctoral
Program of Higher Education (No. 20090121120007), and the
Scientific Research Foundation for the Returned Overseas
Chinese Scholars, Ministry of Education of China for additional
financial supports.
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