Preparation of Z-α,β-unsaturated diazoketones from aldehydes. Application in the construction of substituted dihydropyridin-3-ones

Article abstract of DOI:10.1021/jo401191s

The stereoselective preparation of α,β-unsaturated diazoketones with Z geometry is described from aldehydes and a new olefination reagent. When prepared from amino aldehydes, these diazoketones could be converted to substituted dihydropyridin-3-ones in just one step, after an intramolecular N-H insertion reaction. The straightforward synthesis of a natural trihydroxylated piperidine demonstrates the utility of these unsaturated diazoketones for the rapid construction of piperidines.

Full text of DOI:10.1021/jo401191s

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Note
Preparation of Z-alpha,beta-Unsaturated Diazoketones from Aldehydes.
Application in the Construction of Substituted Dihydropyridin-3-ones.
Isac G. Rosset, and Antonio Carlos Bender Burtoloso
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/jo401191s • Publication Date (Web): 15 Aug 2013
Downloaded from http://pubs.acs.org on August 16, 2013
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Preparation of Z-α,β-Unsaturated Diazoketones from Aldehydes. Application in
the Construction of Substituted Dihydropyridin-3-ones.
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Isac G. Rosset and Antonio C. B. Burtoloso*
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Instituto de Química de São Carlos, Universidade de São Paulo, CEP 13560-970, São Carlos,
SP, Brasil.
antonio@iqsc.usp.br
RECEIVED DATE (will be automatically inserted after manuscript is accepted).
_____________________________________________________________________________
The stereoselective preparation of α,β-unsaturated diazoketones with Z geometry is described
from aldehydes and a new olefination reagent. When prepared from amino-aldehydes, these
diazoketones could be converted to substituted dihydropyridin-3-ones in just one step, after an
intramolecular N-H insertion reaction. The straightforward synthesis of
a natural
trihydroxylated piperidine demonstrates the utility of these unsaturated diazoketones for the
rapid construction of piperidines.
________________________________________________________________________
Diazocompounds are a very interesting class of compounds that can promote a wide
range of reactions, such as cyclopropanations, insertion reactions, ylide formation, dimerization,
and elimination and formation of ketenes by the Wolff rearrangement, among others.1 An
interesting class of these diazocompounds is the α,β-unsaturated diazoketones,2 which has
received little attention when compared to the saturated ones due to the difficulty of its
preparation by the usual existing methods.3 Recently,2a we described a methodology for the
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synthesis of E-α,β-unsaturated diazoketones from diazophosphonate 1, and their use as efficient
platforms in the synthesis of indolizidines2b,c (Scheme 1, Chart A). We wondered if we could
also extend this method to the synthesis of the rare Z isomers after developing new types of
Still-Gennari4 or Ando phosphonates5 such as 2 or 3 (Scheme 1, Chart B). Interestingly, the
success in this transformation could also permit the synthesis of γ-amino-unsaturated
diazoketones like 4 if amino-aldehydes6 are used. These intermediates would possess the proper
Z geometry for a direct cyclization to furnish highly functionalized piperidine systems, such as
dihydropyridin-3-ones like 5. Moreover, depending on the amino-aldehyde that is employed,
not only piperidines, but also indolizidine and quinolizidine systems could be achieved.
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Scheme 1. Unsaturated diazoketones as platforms for the direct synthesis of alkaloids.
Herein, we would like to show the development of a new Horner-Wadsworth-Emmons
(HWE) reagent for the synthesis of α,β-unsaturated diazoketones with Z geometry and the
conversion of some of them to substituted dihydropyridin-3-ones like 5 in just one step after an
intramolecular N-H insertion reaction.7 Moreover, a three-step synthesis of a natural
trihydroxylated piperidine8 demonstrates the utility of these unsaturated diazoketones for the
rapid construction of piperidines. Dihydropyridin-3-ones similar to 5 have already been applied
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with success in the total syntheses of haouamine,9,10 paroxetine,11 and ergolines,12 and they can
also be powerful platforms in the synthesis of many other piperidines. Notwithstanding these
applications, straightforward methods to prepare substituted dihydropyridin-3-ones (especially
enantiopure ones) are still scarce,13 being that olefin metathesis13i,m is one of the most efficient
methods to prepare them.
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To investigate our proposal, we started our work by synthesizing new
diazophosphonates 6-814 (Scheme 2), with the aim of achieving the desired Z-α,β-unsaturated
diazoketones by an Ando-type HWE reaction.5 It is worth mentioning that the most useful
methodology to prepare diazoketones, involving diazomethane acylation in the presence of acyl
chlorides or mixed anhydrides, is generally not good for the synthesis of α,β-unsaturated
diazoketones. This is because dipolar cycloaddition to the conjugated double bond rapidly
occurs, resulting in the formation of pyrazolines.15 Diazophosphonate 6, 7, and 8 were prepared
by the reaction of diazomethane and the activated 2-(aryloxyphosphoryl)acetic acids16; they are
stable yellow solids that can be stored for months without decomposition.. This stability was
also demonstrated after thermogravimetric analysis17 from diazophosphonate 6, showing no
decomposition in temperatures up to 150 oC.
Scheme 2. New Ando-type phosphonates.
ꢀ
With a secure and reproducible way to prepare 6, 7, and 8, we then studied the
preparation of the Z-unsaturated diazoketones, using benzaldehyde as a model in the HWE
reaction (Table 1).
Table 1. Evaluation of the HWE reaction between diazophosphonates 6-8 and benzaldehyde.
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Entrya phosphonate
Base
NaH
Yieldb Z:E c
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2
6
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8
6
6
6
6
6
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8
6
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70
63
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92
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7:3
6:4
1:1
7:3
7:3
1:1
6:4
9:1
8:2
8:2
8:2
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NaH
3
NaH
4d
5e
6
NaH
NaH
DIPEA
BuLi
7
8
t-BuOK
t-BuOK
t-BuOK
t-BuOK
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10
11f
a
Unless otherwise noted, all the reactions were carried out using 0.16 mmol of the aldehyde, 0.16 mmol of the
phosphonate and 0.18 mmol of the base. For the generation of the phosphonate anion, a 0.05 M solution of 6-8 in
b
THF was added to a suspension of the base in THF (0.3M). Yields (%) for E + Z after column chromatography
purification. c Measured by H NMR. d A 0.3 M solution of the phosphonate was added to the base. e 2 equiv. of the
1
phosphonate anion was employed. f 3 equiv. of 18-crown-6 ether was used as additive.
As depicted in Table 1, the use of potassium t-butoxide as the base (entry 8) was crucial
to guarantee a high yield (92%) and a high level of Z-selectivity (Z:E ratio = 9:1). Employing
sodium hydride, a similar yield could be obtained only when two equivalents of
diazophosphonate 6 were used, and with the cost of a lower diastereoselectivity (Z:E ratio =
7:3). The modification of the aromatic ring of the phosphonate (sterically and electronically) did
not improve the yield or the Z:E ratio of the HWE reactions. The use of this best condition for
the HWE reaction could also be extended to 4-methoxybenzaldehyde, 4-nitrobenzaldehyde, and
hexanal, leading to the respective unsaturated diazoketones 10-12 in very good yields and
excellent diastereoselectivities (Figure 1).
ꢀ
Figure 1. Synthesis of Z-α,β-unsaturated diazoketones from aromatic and aliphatic aldehydes.
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Aiming the expedited preparation of dihydropyridin-3-ones as depicted in Scheme 1
(Chart B), we then turned our attention to evaluating the scope of this modified HWE reaction
in the presence of amino-aldehydes (Table 2). Unlike the aromatic and aliphatic aldehydes,
amino-aldehydes proved to have different behaviors in the HWE reaction with
diazophosphonate 6. For example, depending on the nitrogen protecting group and the size of
the substituent alpha to the carbonyl group (R1), different results18 were obtained with respect to
yields (40-74%) and diastereoselectivities (6:4 to 10:0) (Table 2).
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Table 2. Synthesis of diverse Z-α,β-unsaturated diazoketones from amino-aldehydes19
ꢀ
Yield Za Yield Ea Z:E
ꢀ
diazoketone
Yield Za Yield Ea Z:E
diazoketone
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50
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20
8:2
7:3
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7:3
40
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6:4
74
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0
10:0
8:2
73
63
0
7
10:0
9:1
14
a Isolated yields after column chromatography purification and isomer separation.
Next, in order to reach the desired dihydropyridin-3-ones, we evaluated the cyclization of the
synthesized diazoketones by a metal-catalyzed intramolecular N-H insertion reaction. It is
important to note that, although N-H insertion reactions from diazoketones have been well
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described for decades,1 no example of this transformation is available in the literature from α,β-
unsaturated diazoketones as substrates. For this peculiar case, the presence of the double bond
(and the acidic hydrogen in the gamma position) in these unsaturated diazoketones may set a
troubled scenario when compared to the saturated ones, creating the possibility of competing
reactions such as cyclopropanation and C-H insertion reactions. To verify this, an exhaustive
study was necessary in order to find the best conditions for the desired intramolecular N-H
insertion reaction (see supporting information for details). In this study, the simple Cbz-, Ts-,
and Boc-protected diazoketones 13-15 were employed as a model in the presence of different
rhodium and copper salts as catalysts. Based on the pioneering works of Christensen,7a
Rapoport,7b and others7c-h for this type of transformation, rhodium catalysts were the first choice.
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To our surprise rhodium catalysts were completely non-selective and furnished at 25 C a
complex mixture of products (TLC analysis), probably arising from competing C-H and C=C
insertion reactions as mentioned above. We then turned our attention to copper catalysts.
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Although they were shown to be inactive at 25 C, reactions carried out at 80o C led to yields
ranging from 30-70%. For those catalysts, the tosyl protecting group furnished the best result
(Figure 2). In agreement with the literature, the combination of the tosyl protecting group and
copper catalysts had been previously claimed by Wang20 as the best choice for intramolecular
N-H insertion reactions, especially when C-H insertions need to be avoided. After finding the
suitable conditions for the intramolecular N-H insertion reactions from γ-amino unsaturated
diazoketones 13-15, we then extended it to the synthesis of 2-substituted dihydropyridin-3-ones
25-2821 with different patterns of substitution (Figure 2).
Figure 2. Synthesis of dihydropyridin-3-ones from unsaturated diazoketones 13-19.
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In addition, to illustrate the utility of these dihydropyridin-3-ones in the direct synthesis of
hydroxylated piperidines, compound 22 was converted to (+/-)-(3R,5R)-piperidine-3,4,5-triol
31, an α-glycosidadse and β-galactosidase inhibitor isolated from Eupatorium fortunei TURZ22
(Scheme 3). Luche reduction23 from 22, followed by a highly selective OsO4 catalyzed
dihydroxylation reaction24 and tosyl group removal,25 led to the natural trihydroxylated
piperidine 31 after this sequence of three simple steps. All of the spectroscopic data for 31 is in
accordance with those published in the literature.22,26 It is interesting to note that chiral 31 could
also be prepared in an analogous sequence just by employing a CBS reduction from
dihydropyridin-3-one 22 instead of a Luche reduction.
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Scheme 3. Dihydropyridin-3-one 22 as an advanced intermediate in the total synthesis of 3,4,5-
trihydroxypiperidine 31.
In conclusion, we have developed a two-step method for easy access to highly functionalized
piperidine systems, such as dihydropyridin-3-ones, from aldehydes. This could be accomplished
after an unusual type of intramolecular N-H insertion reaction from Z-unsaturated diazoketones.
These rare diazoketones could be prepared by employing a new type of olefination reagent and
commercially available or easily prepared amino-aldehydes. The sequence is direct and permits
the expedited synthesis of hydroxylated piperidines, as was demonstrated during the preparation
of the natural piperidine 31. The synthesis of more complex piperidines, such as nojirimycin
analogues from chiral dihydropyridin-3-ones 28, is under way in our laboratory.
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EXPERIMENTAL SECTION
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Diphenyl (3-diazo-2-oxopropyl)phosphonate (6). 2-(diphenoxyphosphoryl)acetic acid (4.5 g,
15.4 mmol, 1.0 equiv) was added to a 100 mL flame-dried round bottom flask, followed by the
addition of dry toluene (3 x 20 mL) for azeothropic removal of moisture. Next, dry chloroform
(38.5 mL) was added and the system cooled to 0°C. Freshly distilled oxalyl chloride (4.0 mL,
46.2 mmol, 3.0 equiv) was then added dropwise to the reaction vessel and the solution stirred at
reflux for two hours. After this period, the solvent and volatiles were removed on the rotary
evaporator and the resultant residue was dissolved in dry tetrahydrofuran (THF) (14.4 mL)
(Careful: The acid chloride from 2-(diphenoxyphosphoryl)acetic acid is very unstable and care
should be exercised during these operations to avoid its hydrolysis). To the acid chloride
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solution, at 0 C, a cooled and freshly prepared 0.4 M ethereal solution of diazomethane (115
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mL) was added and the reaction allowed stirring at 0 C for 10 min. After that, the solvent was
removed in the rotary evaporator (Careful: Before concentrating on a rotary evaporator, it is
important to remove the excess of diazomethane by passing argon through the solution during 5
minutes) and the residue was purified by flash column chromatography (diethyl diethyl
ether:hexanes 8:2) to furnish the diphenyl (3-diazo-2-oxopropyl)phosphonate (6) (2.44 g, 7.70
o
mmol, 55%) as a yellow solid. mp = 61-63 C, Rf = 0.33 (silica gel, diethyl ether:hexanes =
8:2); IR (neat) νmax = 3101, 3070, 2970, 2920, 2110, 1636, 1591, 1491, 1362, 1279, 1213, 1188,
1163, 945, 768, 690, 617 cm-1; 1H NMR (200 MHz, CDCl3) δ 7.49–7.09 (m, 10H), 5.68 (s, 1H),
3.25 (d, JH-P = 21.8 Hz, 2H) ppm; 13C NMR (50 MHz, CDCl3) δ 183.6, 149.8 (d, JC-P = 8.8 Hz),
129.8 (d, JC-P = 0.7 Hz), 125.6 (d, JC-P = 1.2 Hz), 120.6 (d, JC-P = 4.4 Hz), 57.1, 39.8 (d, JC-P
=
132.2 Hz) ppm; HRMS (ESI-TOF): calcd for C15H14N2O4P [M + H+]: 317.06857, found
317.06711.
Di-o-tolyl (3-diazo-2-oxopropyl)phosphonate (7). (2.60 g, 7.55 mmol, 50%) as a yellow solid.
o
mp = 59-61 C, Rf = 0.32 (silica gel, diethyl ether:hexanes = 8:2); IR (neat) νmax = 3084, 3070,
2962, 2922, 2108, 1637, 1585, 1493, 1462, 1358, 1275, 1229, 1169, 1109, 1063, 1051, 951,
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845, 806, 762, 708 cm-1; H NMR (400 MHz, CDCl3) δ 7.29–7.05 (m, 8H), 5.71 (s, 1H), 3.29
5
6
(d, JH-P = 21.8 Hz, 2H), 2.24 (s, 6H) ppm; 13C NMR (100 MHz, CDCl3) δ 183.6, 148.7 (d, JC-P
=
7
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9.1 Hz), 131.6, 129.5 (d, JC-P = 5.4 Hz), 127.2, 125.5, 120.4, 56.9, 40.4 (d, JC-P = 132.4 Hz),
9
16.4 ppm; HRMS (ESI-TOF): calcd for C17H18N2O4P [M + H+]: 345.0999, found 345.0984.
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Bis(4-methoxyphenyl) (3-diazo-2-oxopropyl)phosphonate (8). (2.44 g, 7.70 mmol, 45%) as a
yellow solid. mp = 67-69 oC, Rf = 0.35 (silica gel, diethyl ether:hexanes = 8:2); IR (neat) νmax
=
3107, 3078, 3003, 2957, 2941, 2912, 2837, 2110, 1736, 1634, 1502, 1466, 1443, 1360, 1273,
1252, 1207, 1186, 1103, 1034, 947, 835, 810 cm-1; 1H NMR (200 MHz, CDCl3) δ 7.18–7.08 (m,
4H), 6.89–6.81 (m, 4H), 5.68 (s, 1H), 3.78 (s, 6H), 3.21 (d, JH-P = 21.8 Hz, 2H).; 13C NMR (50
MHz, CDCl3) δ 183.7, 157.1, 143.3 (d, JC-P = 8.9 Hz), 121.5 (d, JC-P = 4.1 Hz), 114.7, 57.0,
55.6, 39.5 (d, JC-P = 132.1 Hz), 30.5 ppm; HRMS (ESI-TOF): calcd for C17H18N2O6P [M + H+]:
377.0897, found 377.0918.
General Procedure for the HWE Reaction (t-BuOK as base):
(Z)-1-Diazo-4-phenylbut-3-en-2-one (9). In a flame-dried round bottom flask of 10 mL, under
argon atmosphere, was added t-BuOK (20.1 mg, 0.174 mmol, 1.1 equiv) and dry THF (580 µL).
The suspension was cooled to
0
oC and
a
solution of diphenyl (3-diazo-2-
oxopropyl)phosphonate (6) (50.0 mg, 0.158 mmol, 1.0 equiv) in dry THF (3.2 mL) was added.
o
After 10 min, the solution was cooled to -78 C and a solution of benzaldehyde (16 µL, 0.158
mmol, 1.0 equiv) in dry THF (790 µL) was added. After 1 h, the temperature was immediately
allowed to rise to 0 °C and stirred for 1 additional hour, when a saturated aqueous NH4Cl
solution (10 mL) was added to the reaction vessel. Next, the aqueous layer was extracted with
ethyl acetate (3 x 20 mL) and the combined organic layers were washed with water (15 mL),
brine (15 mL), dried over Na2SO4, filtered, and the solvent removed under reduced pressure.
The residue was purified by flash column chromatography (silica gel, diethyl ether:hexanes =
8:2) to give (Z)-1-diazo-4-phenylbut-3-en-2-one (9) (22.6 mg, 0.131 mmol, 83% yield) + the E
isomer (2,8 mg, 0.016 mmol, 9% yield) as yellow oils. Rf = 0.60; IR (neat) νmax = 3099, 3088,
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3024, 2096, 1634, 1603, 1493, 1450, 1423, 1391, 1339, 1148, 1103, 1067, 922, 843, 802, 698,
609, 561 cm-1; 1H NMR (400 MHz, CDCl3) δ 7.53 (m, 2H), 7.39–7.33 (m, 3H), 6.87 (d, J = 12.6
Hz, 1H), 6.03 (d, J = 12.7 Hz, 1H), 5.16 (s, 1H) ppm; 13C NMR (100 MHz, CDCl3) δ 186.5,
139.5, 135.0, 129.7, 129.1, 128.3, 127.2, 57.3 ppm; HRMS (ESI-TOF): calcd for C10H9N2O
[M+H+]: 173.0709, found 173.0798.
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(Z)-1-Diazo-4-(4-nitrophenyl)but-3-en-2-one (10). (31.7 mg, 0.146 mmol, 92% yield) as a
yellow solid, mp = 90-91 ºC, Rf = 0.37 (diethyl ether:hexanes 8:2); IR (neat) νmax = 3109, 2920,
2853, 2102, 1639, 1591, 1512, 1429, 1335, 1146, 1107, 874, 752, 704, 513 cm-1; 1H NMR (500
MHz, CDCl3) δ 8.23–8.15 (m, 2H), 7.73 (d, J = 8.0 Hz, 2H), 6.83 (d, J = 12.4 Hz, 1H), 6.17 (d,
J = 12.4 Hz, 1H), 5.31 (s, 1H) ppm; 13C NMR (125 MHz, CDCl3) 183.1, 147.7, 141.5, 137.4,
130.8, 129.1, 123.3, 58.0 ppm, HRMS (ESI) calcd for C10H8N3O3 [M+H+]: 218.0560, found:
218.0562.
(Z)-1-Diazo-4-(4-methoxyphenyl)but-3-en-2-one (11). (23.0 mg, 0.114 mmol, 72% yield) as a
yellow solid, mp = 120-121 ºC, Rf = 0.38 (diethyl ether:hexanes 8:2); IR (neat) νmax = 3062,
1
2090, 1643, 1587, 1512, 1421, 1367, 1551, 1172, 1093, 977, 827 cm-1; H NMR (500 MHz,
CDCl3) δ 7.65 (s, 2H), 6.90–6.82 (m, 2H), 6.75 (d, J = 12.6 Hz, 1H), 5.90 (d, J = 11.7 Hz, 1H),
5.23 (s, 1H), 3.83 (s, 3H) ppm; 13C NMR (125 MHz, CDCl3) 184.4, 161.5, 140.5, 129.9, 129.7,
127.1, 114.4, 55.9, 55.4 ppm, HRMS (ESI) calcd for C11H11N2O2 [M+H+]: 203.0815, found:
203.0812.
(Z)-1-diazonon-3-en-2-one (12). (20.5 mg, 0.123 mmol, 78% yield) as a yellow oil, Rf = 0.43
1
(acetone:hexanes 2:8); IR (neat) νmax = 2956, 2927, 2102, 1652, 1367 cm-1; H NMR (500
MHz, CDCl3) δ 6.04 (dt, J = 11.1, 7.5 Hz, 1H), 5.85 (s, 1H), 5.24 (s, 1H), 2.69 (d, J = 7.1 Hz,
2H), 1.47–1.41 (m, 2H), 1.36–1.17 (m, 6H), 0.88 (t, J = 6.9 Hz, 3H) ppm; 13C NMR (125 MHz,
CDCl3) δ 185.7, 148.0, 124.8, 56.7, 31.5, 29.5, 28.9, 22.5, 14.2. ppm, HRMS (ESI) calcd for
C9H15N2O [M+H+]: 167.1179, found: 167.1177.
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(Z)-Benzyl (5-diazo-4-oxopent-2-en-1-yl)carbamate (13). (28.0 mg, 0.108 mmol, 68% yield)
as a yellow oil, Rf = 0.35 (diethyl ether:hexanes 8:2); IR (neat) νmax = 3414, 3337, 3096, 3063,
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3043, 2102, 1713, 1643, 1605, 1524, 1454, 1416, 1346, 1265, 1148, 739 cm-1; H NMR (600
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MHz, CDCl3) δ 7.36–7.34 (m, 3H), 7.33 – 7.30 (m, 2H), 6.13 (s, 1H), 5.92 (d, J = 9.2 Hz, 1H),
5.44 (s, 1H), 5.33 (s, 1H), 5.10 (s, 2H), 4.31 (s, 2H).; 13C NMR (150 MHz, CDCl3) δ 185.1,
156.5, 143.6, 136.5, 128.6, 128.5, 128.1, 126.1, 66.8, 57.4, 39.9, 39.7 ppm; HRMS (ESI) calcd
for C13H14N3O3 [M+H+]: 260.1030, found: 260.1025.
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(Z)-N-(5-diazo-4-oxopent-2-en-1-yl)-4-methylbenzenesulfonamide (14). (22.0 mg, 0.079
o
mmol, 50% yield) as a yellow solid, mp = 97-98 C, Rf = 0.25 (diethyl ether:hexanes 8:2); IR
(neat) νmax = 3157, 3115, 2918, 2885, 2862, 2154, 2098, 1639, 1576, 1418, 1340, 1327, 1165,
1068, 883, 662 cm-1; 1H NMR (600 MHz, CDCl3) δ 7.75 (d, J = 8.3 Hz, 2H), 7.30 (dd, J = 8.5,
0.6 Hz, 2H), 6.13–6.08 (m, 1H), 5.89 (d, J = 11.2 Hz, 1H), 5.46 (s, 1H), 5.31 (s, 1H), 4.00 (s,
2H), 2.42 (s, 3H); 13C NMR (150 MHz, CDCl3) δ 185.0, 143.5, 142.0, 136.9, 129.8, 127.1,
126.7, 57.8, 41.7, 21.5 ppm; HRMS (ESI) calcd for C12H14N3O3S [M+H+]: 280.0750, found:
280.0732.
(Z)-tert-butyl (5-diazo-4-oxopent-2-en-1-yl)carbamate (15) (14.2 mg, 0.063 mmol, 40%
yield) as a yellow oil, Rf = 0.43 (diethyl ether:hexanes 8:2); IR (neat) νmax = 3352, 3096, 3080,
2976, 2930, 2102, 1699, 1643, 1605, 1514, 1416, 1344, 1275, 1252, 1169, 1070, 862, 783 cm-1;
1H NMR (400 MHz, CDCl3) δ 6.08 (s, 1H), 5.88 (d, J = 9.7 Hz, 1H), 5.33 (s, 1H), 5.15 (s, 1H),
4.35–4.09 (m, 2H), 1.41 (s, 9H); 13C NMR (125 MHz, CDCl3) δ 185.1, 156.0, 144.4, 125.7,
79.4, 57.2, 39.4, 28.4 ppm; HRMS (ESI) calcd for C10H16N3O3 [M+H+]: 226.1186, found:
226.1171.
(S,Z)-N-(5-diazo-4-oxo-1-phenylpent-2-en-1-yl)-4-methylbenzenesulfonamide (16). (37.6
mg, 0.115 mmol, 73% yield) as a yellow solid, mp = 147-149oC, Rf = 0.15 (diethyl
ether:hexanes 8:2); IR (neat) νmax = 3225, 3173, 3097, 3063, 3030, 2980, 2920, 2883, 2745,
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2102, 1734, 1707, 1643, 1589, 1493, 1450, 1418, 1350, 1325, 1288, 1265, 1221, 1159, 1119,
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1094, 1063, 1047, 939, 816, 700, 557 cm-1; H NMR (400 MHz, CDCl3) δ 7.68 (d, J = 8.3 Hz,
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2H), 7.27–7.22 (m, 7H), 6.18 (dd, J = 11.3, 8.8 Hz, 1H), 6.05–5.99 (m, 1H), 5.81 (d, J = 10.6
Hz, 1H), 5.68 (s, 1H), 5.30 (s, 1H), 2.41 (s, 3H) ppm; 13C NMR (100 MHz, CDCl3) δ 184.5,
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144.7, 143.4, 138.8, 137.0, 129.6, 128.9, 128.1, 127.4, 127.1, 124.4, 58.0, 55.2, 21.5 ppm; [α]25
D
= +165.6 (c 8.2, CHCl3), HRMS (ESI) calcd for C18H18N3O3S [M+H+]: 356.1063,
found:356.1065.
(R,Z)-N-(1-((tert-butyldiphenylsilyl)oxy)-6-diazo-5-oxohex-3-en-2-yl)-4-
methylbenzenesulfonamide (17). (51.4 mg, 0.099 mmol, 63% yield) as a yellow solid, mp =
90-92 oC, Rf = 0.45 (diethyl ether:hexanes 8:2); IR (neat) νmax = 3227, 3117, 3070, 3038, 2947,
2924, 2853, 2108, 1643, 1616, 1593, 1489, 1448, 1423, 1360, 1317, 1232, 1188, 1155, 1111,
1074, 1009, 924, 822, 729, 706, 667, 501, 494 cm-1; 1H NMR (400 MHz, CDCl3) δ 7.68 (d, J =
8.3 Hz, 2H), 7.53 (t, J = 7.5 Hz, 4H), 7.45–7.32 (m, 6H), 7.27–7.20 (m, 2H), 6.01 (dd, J = 11.1,
8.3 Hz, 1H), 5.78 (d, J = 10.8 Hz, 1H), 5.51 (d, J = 4.9 Hz, 1H), 5.26 (s, 1H), 5.01 (s, 1H), 3.76–
3.45 (m, 2H), 2.39 (s, 3H), 1.00 (d, J = 14.1 Hz, 9H); 13C NMR (100 MHz, CDCl3) δ 184.2,
144.5, 143.4, 136.9, 135.5, 135.4, 132.6, 129.9, 129.6, 127.8, 127.2, 65.2, 57.4, 53.7, 26.7, 21.5,
19.1 ppm; [α]25 = -100.4 (c 1.17, CHCl3,), HRMS (ESI) calcd for C29H34N3O4SSi [M+H+]:
D
548.2034, found: 548.2034.
(S,Z)-N-(8-diazo-2-methyl-7-oxooct-5-en-4-yl)-4-methylbenzenesulfonamide (18). (25.2 mg,
0.082 mmol, 52% yield) as a yellow solid, mp = 150-151 ºC, Rf = 0.25 (diethyl ether:hexanes
8:2); IR (neat) νmax = 3165, 3088, 2947, 2924, 2866, 2147, 2098, 1649, 1591, 1421, 1367, 1315,
1
1302, 1169, 1153, 1142, 1097, 1068, 935, 808, 660, 581, 550, 486 cm-1; H NMR (200 MHz,
CDCl3) δ 7.71 (d, J = 8.3 Hz, 2H), 7.32–7.22 (m, 2H), 5.86 (dd, J = 11.6, 8.2 Hz, 1H), 5.67 (s,
1H), 5.28 (s, 1H), 4.84–4.65 (m, 1H), 2.41 (s, 3H), 1.68–1.53 (m, 1H), 1.46–1.21 (m, 2H), 0.80
(dd, J = 18.3, 6.5 Hz, 6H) ppm; 13C NMR (50 MHz, CDCl3) δ 184.7, 147.3, 143.1, 137.7, 129.4,
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127.3, 124.2, 57.9, 50.3, 43.4, 24.4, 23.0, 21.5, 21.2 ppm; [α]25D = -90.4 (c 1.26, CHCl3), HRMS
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(ESI) calcd for C16H22N3O3S [M+H+]: 336.1376, found: 336.1373.
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(S,Z)-N-(6-diazo-5-oxohex-3-en-2-yl)-4-methylbenzenesulfonamide (19). (20.9 mg, 0.079
mmol, 50% yield) as a yellow solid, mp = 136-137 ºC, Rf = 0.23 (diethyl ether:hexanes 8:2); IR
(neat) νmax = 3159, 3109, 2980, 2964, 2924, 2870, 2106, 1645, 1593, 1462, 1418, 1369, 1353,
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1321, 1165, 1074, 978, 804, 579 cm-1; H NMR (600 MHz, CDCl3) δ 7.71 (d, J = 8.3 Hz, 2H),
7.28 (d, J = 8.0 Hz, 2H), 5.96 (dd, J = 11.5, 8.1 Hz, 1H), 5.71 (d, J = 11.6 Hz, 1H), 5.38 (s, 1H),
5.29 (s, 1H), 4.81 (dd, J = 14.0, 6.8 Hz, 1H), 2.42 (s, 3H), 1.22 (d, J = 6.9 Hz, 3H); 13C NMR
(150 MHz, CDCl3) δ 184.7, 147.7, 143.3, 137.6, 129.6, 127.2, 124.1, 57.8, 48.2, 21.5, 20.7 ppm;
[α]25D = -94.6º (c 0.82, CHCl3), HRMS (ESI) calcd for C13H16N3O3S [M+H+]: 294.0907, found:
294.0900.
(S,Z)-1-Diazo-4-(1-tosylpyrrolidin-2-yl)but-3-en-2-one (20). (37.3 mg, 0.117 mmol, 74%
yield) as a yellow solid, mp = 109-110 ºC, Rf = 0.43 (diethyl ether:hexanes 8:2); IR (neat) νmax
= 3080, 2953, 2924, 2856, 2096, 1728, 1649, 1605, 1448, 1420, 1348, 1196, 1157, 1109, 1088,
1
1032, 986, 824, 795, 723, 660, 584, 546 cm-1; H NMR (500 MHz, CDCl3) δ 7.69 (d, J = 8.2
Hz, 2H), 7.32 (d, J = 8.0 Hz, 2H), 6.29 (dd, J = 10.9, 8.2 Hz, 1H), 5.87 (d, J = 10.9 Hz, 1H),
5.37 (s, 1H), 5.17 (d, J = 7.1 Hz, 1H), 3.77–3.70 (m, 1H), 3.18 (ddd, J = 10.3, 7.4, 6.1 Hz, 1H),
2.43 (s, 3H), 2.14 (td, J = 13.2, 6.8 Hz, 1H), 1.83–1.75 (m, 1H), 1.68 – 1.54 (m, 2H) ppm; 13C
NMR (125 MHz, CDCl3) δ 184.9, 149.1, 143.5, 133.7, 129.0, 127.7, 123.3, 61.9, 58.5, 49.6,
31.7, 24.3, 21.5 ppm; [α]25 = -8.2 (c 1.21, CHCl3), HRMS (ESI) calcd for C15H18N3O3S
D
[M+H+]: 320.1063, found: 320.1068.
(S,Z)-benzyl 2-(4-diazo-3-oxobut-1-en-1-yl)pyrrolidine-1-carboxylate (21). (26.6 mg, 0.089
mmol, 56% yield) as a yellow oil, Rf = 0.42 (diethyl ether:hexanes 8:2); IR (neat) νmax = 3068,
3032, 2972, 2953, 2878, 2098, 1699, 1645, 1609, 1447, 1414, 1342, 1149, 1119, 1095, 793,
735, 698 cm-1; 1H NMR (200 MHz, CDCl3) δ 7.50–7.20 (m, 5H), 6.17–4.91 (m, 5H), 3.74–3.38
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(m, 2H), 2.51–2.23 (m, 1H), 2.08–1.60 (m, 4H) ppm; 13C NMR (50 MHz, CDCl3)1 δ 185.2,
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155.0, 149.0, 148.1, 136.7, 128.4, 128.2, 127.8, 127.7, 122.8, 66.7, 56.8, 55.9, 47.2, 46.9, 33.2,
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32.5, 30.3, 24.6, 24.1 ppm; [α]25 = -161.9 (c 0.90, CHCl3), HRMS (ESI) calcd for C16H16N3O3
D
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[M-H-]: 298.1197, found: 298.1190.
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General Procedure for the N-H Insertion Reaction:
1-tosyl-1,6-dihydropyridin-3(2H)-one (22). In a flame-dried round bottom flask of 5 mL was
added (Z)-N-(5-diazo-4-oxopent-2-en-1-yl)-4-methylbenzenesulfonamide (14) (1.0 eq., 0.090
mmol, 25 mg) dissolved in distilled benzene (1.8 mL, 0.05 mol/L). The mixture was then
warmed to reflux, followed by the addition of copper(II) acetylacetonate (0,1 eq., 8.95 µmol, 2.3
mg). After 1 min under stirring, the reaction was cooled and the solvent removed under reduced
pressure. Next, the crude product was purified by flash column chromatography
(hexanes:diethyl ether 2:8) to furnish 1-tosyl-1,6-dihydropyridin-3(2H)-one (22) (15.7 mg,
0.063 mmol, 70% yield) as a white solid. Rf = 0.60 (silica gel, hexanes:diethyl ether 2:8); mp =
o
101-103 C; IR (neat) νmax = 3157, 3115, 2918, 2885, 2862, 2154, 2098, 1639, 1576, 1450,
1418, 1340, 1327, 1230, 1165, 1111, 1095, 1068, 1041, 935, 883, 812, 798, 779, 735, 706, 662,
579, 554, 523 cm-1; 1H NMR (400 MHz, CDCl3) δ 7.67 (d, J = 8.3 Hz, 2H), 7.35 (d, J = 8.0 Hz,
2H), 6.92 (dt, J = 10.3, 3.7 Hz, 1H), 6.06 (dt, J = 10.3, 2.1 Hz, 1H), 3.97 (s, 2H), 3.81 (s, 2H),
2.44 (s, 3H) ppm; 13C NMR (100 MHz, CDCl3) δ 191.1, 144.9, 144.5, 132.8, 130.1, 128.0,
127.7, 52.8, 44.5, 21.6 ppm; HRMS (ESI) calcd for C12H14NO3S [M+H+]: 252.0689, found:
252.0685.
(S)-6-isobutyl-1-tosyl-1,6-dihydropyridin-3(2H)-one (25). (10.1 mg, 0.033 mmol, 55% yield)
as a white solid, mp = 118-120oC; Rf = 0.66 (diethyl ether:hexanes 8:2); IR (neat) νmax = 2959,
2924, 2866, 1701, 1690, 1597, 1468, 1387, 1340, 1259, 1161, 1132, 1090, 1040, 978, 905, 816,
758, 689, 585, 555 cm-1; 1H NMR (200 MHz, CDCl3) δ 7.60 (d, J = 8.3 Hz, 2H), 7.25 (d, J = 8.8
Hz, 2H), 6.71 (dd, J = 10.5, 4.9 Hz, 1H), 5.65 (d, J = 10.4 Hz, 1H), 4.63 (dt, J = 9.5, 4.8 Hz,
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1H), 4.38 (d, J = 18.9 Hz, 1H), 3.87 (d, J = 19.0 Hz, 1H), 2.39 (s, 3H), 1.94–1.86 (m, 1H), 1.63–
1.55 (m, 1H), 1.38 (m, 1H), 1.03 (t, J = 8.0 Hz, 6H) ppm; 13C NMR (50 MHz, CDCl3) δ 191.6,
149.5, 143.9, 136.1, 129.9, 129.1, 127.2, 126.4, 122.8, 52.2, 49.1, 40.5, 25.2, 23.0, 21.7, 21.5
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ppm; [α]25 = +19.1 (c 1.80, CHCl3), HRMS (ESI) calcd for C16H22NO3S [M+H+]: 308.1315,
D
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found: 308.1308.
(S)-6-phenyl-1-tosyl-1,6-dihydropyridin-3(2H)-one (26). (8.3 mg, 0.025 mmol, 45% yield) as
o
a white solid, mp = 146-147 C; Rf = 0.38 (diethyl ether:hexanes 1:1); IR (neat) νmax = 3059,
3042, 3026, 2970, 2922, 2885, 2854, 1682, 1585, 1491, 1452, 1389, 1346, 1257, 1167, 1090,
1043, 982, 926, 910, 764, 706, 687, 550 cm-1; H NMR (400 MHz, CDCl3) δ 7.58 (d, J = 8.3
1
Hz, 2H), 7.37 (s, 5H), 7.23 (d, J = 8.0 Hz, 2H), 6.96 (dd, J = 10.4, 5.2 Hz, 1H), 5.98 (dd, J =
10.4, 1.2 Hz, 1H), 5.81 (dd, J = 5.1, 1.3 Hz, 1H), 4.31 (d, J = 18.6 Hz, 1H), 3.70 (d, J = 18.6 Hz,
1H), 2.39 (s, 3H) ppm; 13C NMR (100 MHz, CDCl3) δ 191.4, 163.7, 146.6, 144.1, 136.0, 134.6,
129.9, 129.0, 128.9, 128.3, 128.1, 127.2, 56.3, 49.5, 21.5 ppm; [α]25 = -105.5 (c = 0.80,
D
CHCl3), HRMS (ESI) calcd for C18H18NO3S [M+H+]: 328.1002, found: 328.0997.
(S)-6-methyl-1-tosyl-1,6-dihydropyridin-3(2H)-one (27). (9.9 mg, 0.038 mmol, 55% yield) as
o
a white solid, mp = 85-86 C; Rf = 0.48 (diethyl ether:hexanes 8:2); IR (neat) νmax = 2922,
2867, 2870, 2853, 1695, 1597, 1458, 1391, 1342, 1259, 1192, 1165, 1128, 1092, 999, 922, 814,
781, 708, 687, 555 cm-1; 1H NMR (400 MHz, CDCl3) δ 7.62 (d, J = 8.2 Hz, 2H), 7.28–7.24 (m,
2H), 6.77 (dd, J = 10.4, 5.0 Hz, 1H), 5.78 (d, J = 10.4 Hz, 1H), 4.79–4.69 (m, 1H), 4.35 (d, J =
18.5 Hz, 1H), 3.87 (d, J = 18.5 Hz, 1H), 2.40 (s, 3H), 1.39 (d, J = 7.0 Hz, 3H) ppm; 13C NMR
(100 MHz, CDCl3) δ 191.5, 150.3, 144.0, 136.2, 130.0, 127.1, 126.2, 49.7, 48.7, 21.5, 17.5 ppm;
[α]25 = -19.8 (c 1.50, CHCl3,), HRMS (ESI) calcd for C13H16NO3S [M+H+]: 266.0845, found:
D
266.0833.
(R)-6-(((tert-butyldiphenylsilyl)oxy)methyl)-1-tosyl-1,6-dihydropyridin-3(2H)-one
(28).
(8.5 mg, 0.016 mmol, 50% yield) as a white solid, Rf = 0.40 (diethyl ether:hexanes 1:1); IR
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(neat) νmax = 2951, 2928, 2889, 2856, 1693, 1595, 1470, 1427, 1393, 1350, 1261, 1186, 1163,
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1111, 1095, 984, 908, 820, 773, 741, 706, 687, 646, 611, 548, 503, 494 cm-1; H NMR (400
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MHz, CDCl3) δ 7.61–7.55 (m, 6H), 7.48–7.35 (m, 6H), 7.22 (d, J = 8.0 Hz, 2H), 6.70 (dd, J =
10.5, 5.0 Hz, 1H), 5.93 (dd, J = 10.5, 1.3 Hz, 1H), 4.64 (dd, J = 8.2, 3.9 Hz, 1H), 4.35 (d, J =
18.5 Hz, 1H), 4.09 (d, J = 18.5 Hz, 1H), 4.04 (dd, J = 10.6, 4.9 Hz, 1H), 3.83 (dd, J = 10.5, 4.1
Hz, 1H), 2.39 (s, 3H), 1.00 (s, 9H) ppm; 13C NMR (100 MHz, CDCl3) δ 191.7, 146.5, 143.9,
135.7, 135.5, 132.3, 130.0, 129.9, 128.6, 127.9, 127.0, 65.4, 55.0, 51.3, 26.7, 21.5, 19.0 ppm;
[α]25D = +120.3 (c 0.6, CHCl3), HRMS (ESI) calcd for C29H34NO4SSi [M+H+]: 520.1972, found:
520.1972.
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(±)-1-Tosyl-1,2,3,6-tetrahydropyridin-3-ol (29). Cerium trichloride heptahydrate (0.2 mL of a
0.4 M solution in methanol, 0.08 mmol) was added to a stirred solution of 1-tosyl-1,6-
dihydropyridin-3(2H)-one (32) (20 mg, 0.080 mmol) in dichloromethane (5 mL) at -78 °C.
After 0.25 h, sodium borohydride (45.2 mg, 1.194 mmol) was added and the resulting solution
was stirred for 1 h. After this period, the reaction was warmed to 25 °C and quenched with
water (2.7 mL). The layers were separated and the aqueous portion was extracted with
dichloromethane (3 x 5 mL). The combined organic layers were dried (MgSO4) and
concentrated under reduced pressure to give pure (±)-1-tosyl-1,2,3,6-tetrahydropyridin-3-ol (38)
o
as a white solid (24.5 mg, 0.097 mmol, 98% yield). mp = 100-102 C; Rf = 0.60 (hexanes:ethyl
acetate 1:1); IR (neat) νmax = 3063, 3047, 2980, 2885, 2853, 1595, 1493, 1458, 1400, 1335,
1310, 1290, 1259, 1225, 1161, 1138, 1095, 978, 945, 903, 831, 816, 729, 708, 685, 650, 571,
554, 536 cm-1; 1H NMR (400 MHz, CDCl3) δ 7.70–7.67 (m, 2H), 7.36 –7.32 (m, 2H), 5.91 (ddt,
J = 9.8, 4.1, 2.1 Hz, 1H), 5.81 (dddd, J = 10.1, 3.7, 2.6, 0.8 Hz, 1H), 4.21 (s, 1H), 3.77 (ddd, J =
16.8, 2.2, 1.6 Hz, 1H), 3.40–3.33 (m, 2H), 3.06 (ddd, J = 11.9, 3.7, 0.7 Hz, 1H), 2.44 (s, 3H), δ
2.03 (d, J = 10.5 Hz, 1H) ppm; 13C NMR (100 MHz, CDCl3) δ 143.9, 133.0, 129.8, 128.2,
127.7, 125.8, 63.4, 50.1, 44.9, 21.5. ppm; HRMS (ESI) calcd for C12H16NO3S [M+H+]:
254.0845, found: 254.0835.
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(±)-1-Tosylpiperidine-3,4,5-triol (30). In a flame-dried round bottom flask of 10 mL was
added (±)-1-tosyl-1,2,3,6-tetrahydropyridin-3-ol (29) (1.0 eq., 0.059 mmol, 15 mg) dissolved in
a mixture of water:acetone (2.1 mL; 9:1). To this mixture was added NMO (2.0 eq., 0.118
mmol, 13.9 mg) and an aqueous solution of OsO4 (19.8 µL, 5 mol%, 2.96 µmol). The reaction
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was stirred at 25 C for 48 h and then quenched with 270 µL of a saturated solution of sodium
bisulfide. Next, the reaction was extracted with ethyl acetate (3 x 10 mL), the solvent dried over
sodium sulfate and removed by reduce pressure. The crude product was purified by flash
column chromatography to furnish (±)-1-tosylpiperidine-3,4,5-triol (30) (10.5 mg, 0.040 mmol,
70% yield). White solid, mp 158-160 oC; Rf = 0.22 (ethyl acetate 100%); IR (neat) νmax = 3475,
3367, 3233, 2918, 2845, 1599, 1464, 1340, 1228, 1156, 1091, 1073, 1026, 961, 933, 850, 811,
710, 694, 653, 565, 549 cm-1; 1H NMR (400 MHz, MeOD) δ 7.70–7.67 (m, 2H), 7.46 –7.42 (m,
2H), 3.97 (dt, J = 6.9, 3.4 Hz, 1H), 3.83 (td, J = 6.5, 3.6 Hz, 1H), 3.47 (dd, J = 6.5, 3.1 Hz, 1H),
3.33 (dt, J = 3.3, 1.6 Hz, 1H), 3.20 (dd, J = 11.7, 3.3 Hz, 1H), 3.05 (ddd, J = 15.1, 11.6, 5.4 Hz,
2H), 2.83 (dd, J = 11.8, 6.4 Hz, 1H), 2.46 (s, 3H) ppm; 13C NMR (100 MHz, MeOD) δ 145.26,
134.66, 130.81, 128.80, 73.27, 68.99, 67.60, 49.57, 49.33, 21.46 ppm; HRMS (ESI) calcd for
C12H18NO5S [M+H+]: 288.0900, found: 288.0901.
(±)piperidine-3,4,5-triol (31). In a 10 mL flask was added sodium metal (0.12 g, 5.0 mmol)
and naphthalene (0.72 g, 5.5 mmol) dissolved in dry THF (1.5 mL). The mixture was stirred
until the solution became dark green. A further solution was prepared by dissolving the (±)-1-
tosylpiperidine-3,4,5-triol (30) (1.0 eq., 0.077 mmol, 22 mg) in 320 µL of THF and cooled to -
o
78 C. Next, the sodium/naphthalene solution was added drop wise into the solution of 39 until
the dark green color persisted for 5 min. Then, 2-3 drops of water was added (until the green
color disappear), and the reaction was diluted with ether (20 mL), dried with Na2SO4, filtered
and the solvent removed under reduced pressure. The product was passed through a column
with Dowex® and was then purified by flash chromatography (1:1 methanol: ethyl acetate) to
1
give the pure piperidine 30 (6.6 mg, 0.077 mmol, 65% yield). H NMR (400 MHz, D2O,
reference acetone δ 2.22) δ 3.99 (m, 1H), 3.77 (m, 1H), 3.57 (dd, J = 8.8, 3.2 Hz, 1H), 3.06
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(ddd, J = 13.2, 4.8, 1.2 Hz, 1H), 2.92 (ddd, J = 14.0, 4.0, 1.2 Hz, 1H), 2.69 (dd, J = 14.0, 2.0 Hz,
1H), 2.37 (dd, J = 13.2, 9.6, 1H) ppm; 13C NMR (100 MHz, D2O; reference acetone δ 215.9) δ
74.0, 68.9, 68.6, 48.8, 48.4. Spectroscopic data is in accordance with those published in the
literature.22,26
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Acknowledgment We thank FAPESP (Research Supporting Foundation of the State of Sao
Paulo) for financial support (2007/04170-7 and 2012/04685-5) and a fellowship to IGR
(2010/18801-1). We also thank CNPq (307905/2009-8) for a research fellowship to A.C.B.B.
We also thank IQSC-USP for the facilities, Professor Timothy Brocksom (UFSCar) for optical
rotation analysis, Professor Antonio Aprígio da Silva Curvelo and Luiz A. Ramos for
thermogravimetric analysis and DQO-UFSCar for some NMR analyses.
ꢀ
Supporting Information Available. NMR spectra of all new compounds, N-H insertion
reaction studies, chiral HPLC studies and thermogravimetric analysis. This material is available
free of charge via the Internet at http://pubs.acs.org/
References and Footnotes
(1) Doyle, M. P.; McKervey, M. A.; Ye, T. Modern Catalytic Methods for Organic Synthesis
with Diazo Compounds: From Cyclopropanes to Ylides; New York, 1998.
(2) (a) Pinho, V. D.; Burtoloso, A. C. B. J. Org. Chem. 2011, 76, 289; and references cited
therein; (b) Pinho, V. D.; Burtoloso, A. C. B. Tetrahedron Lett. 2012, 53, 876; (c) Bernardim,
B.; Pinho, V. D.; Burtoloso, A. C. B. J. Org. Chem. 2012, 77, 9926.
(3) Maas, G. Angew. Chem., Int. Ed. 2009, 48, 8186.
(4) Still, W. C.; Gennari, C. Tetrahedron Lett. 1983, 24, 4405.
(5) (a) Ando, K. J. Org. Chem. 1997, 62, 1934; (b) Ando, K. J. Org. Chem. 1998, 63, 8411; (c)
Ando, K. J. Org. Chem. 1999, 64, 8406.
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(6) Protected amino-aldehydes are commercially available or can be readily prepared in
multigram quantities from the corresponding amino acids in two to three steps.
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(7) For pioneering contributions in the intramolecular N-H insertion reactions, see: (a) Lama, L.
D.; Christensen, B. G. Tetrahedron Lett. 1978, 24, 4233. (b) Moyer, M. P.; Feldman, P. L.;
Rapoport, H. J. Org. Chem. 1985, 50, 5223. (c) Moody, C. J.; Pearson, C. J.; Lawton, G.
Tetrahedron Lett. 1985, 26, 3167. (d) Ko, K.; Lee, K.; Kim, W. Tetrahedron Lett. 1992, 33,
6651. (e) Hanessian, S.; Fu, J.; Chiara, J.; Di Fabio, R. Tetrahedron Lett. 1993, 34, 4157. (f)
Podlech, J.; Seebach, D. Helv. Chim. Acta. 1995, 78, 1238. (g) Garcia, C. F.; McKervey, M. A.;
Ye, T. J. Chem. Soc. Chem. Commun. 1996, 1465.
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(8) Hydroxylated piperidines are well-known for their ability to act as potent α and β
glycosidase inhibitors. Please see: Asano, N. Curr. Top. Med. Chem. 2003, 3, 471-484.
(9) Fürstner, A.; Ackerstaff, J. Chem. Commun. 2008, 2870.
(10) Matveenko, M.; Liang, G.; Lauterwasser, E. M. W.; Zubía, E.; Trauner, D. J. Am. Chem.
Soc. 2012, 134, 9291–9295.Koech, P. K.;
(11) Koech, P. K.; Krische, M. J. Tetrahedron 2006, 62, 10594–10602.
(12) Reimann, E.; Erdle, W.; Hargasser, E.; Lotter, H. Monatsh. Chem. 2002, 133, 1017-1030.
(13) (a) Imanishi, T.; Shin, H.; Hanaoka, M.; Momose, T.; Imanishi, I. Chem. Pharm. Bull.
1982, 30, 3617-3623. (b) Chen, L. C.; Wang, E. C.; Lin, J. H.; Wu, S. S. Heterocycles 1984, 22,
2769-2773. (c) Yang, C. F.; Xu, Y. M.; Liao, L. X.; Zhou, W. S. Tetrahedron Lett. 1998, 39,
9227-9228. (d) Harris, J. M.; Padwa, A. Organic Lett. 2002, 4, 2029-2031. (e) Alcudia, A.;
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Eur. J. Org. Chem. 2008, 2008, 4041–4049. (l) Gaucher, X.; Jida, M.; Ollivier. J. Synlett, 2009,
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(14) Although diazophosphonates 6, 7, and 8 could be prepared in multigram quantities and in
good yields from the corresponding carboxylic acids, diazophosphonate 3 (Scheme 1, Chart B)
could not be obtained. Attempts to prepare this phosphonate were fruitless, even after many
conditions were employed.
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(15) Wotiz, J. H.; Buco, S. N. J. Org. Chem. 1955, 20, 210.
(16) 2-(aryloxyphosphoryl)acetic acids can be prepared from diarylphosphites, following
Ando’s procedure.5
(17) Please also see SI for thermogravimetric analysis.
(18) Apparently, small R1 substituents give lower diastereoselectivities. An explanation at this
moment would be merely speculative.
(19) All the unsaturated diazoketones were obtained in an enantiomeric ratio of 98:02 after
careful chiral HPLC analysis.
(20) Wang, J.; Hou, Y.; Wu, P. J. Chem. Soc., Perkin Trans. 1 1999, 2277–2280.
(21) Chiral HPLC analysis showed that no epimerization was observed during the N-H insertion
reaction.
(22) Sekioka, T.; Shibano, M.; Kusano, G. Nat. Med. 1995, 49, 332–335.
(23) Luche, J. L. J. Am. Chem. Soc. 1978, 100, 2226–2227.
(24) VanRheenen, V.; Kelly, R. C.; Cha, D. Y. Tetrahedron Lett. 1976, 17, 1973–1976.
(25) Bergmeier, S. C.; Seth, P. P. Tetrahedron Lett. 1999, 40, 6181–6184.
(26) Ouchi, H.; Mihara, Y.; Takahata, H. J. Org. Chem. 2005, 70, 5207-5214.
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