Iron-catalyzed chemoselective hydride transfer reactions

Article abstract of DOI:10.1016/j.tet.2021.132187

A Diaminocyclopentadienone iron tricarbonyl complex has been applied in chemoselective hydrogen transfer reductions. This bifunctional iron complex demonstrated a broad applicability in mild conditions in various reactions, such as reduction of aldehydes over ketones, reductive alkylation of various functionalized amines with functionalized aldehydes and reduction of α,β-unsaturated ketones into the corresponding saturated ketones. A broad range of functionalized substrates has been isolated in excellent yields with this practical procedure.

Full text of DOI:10.1016/j.tet.2021.132187

Tetrahedron xxx (xxxx) xxx
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Iron-catalyzed chemoselective hydride transfer reactions
a
a
,
b
a
a
ꢀ
ꢀ
Sebastien Coufourier , Daouda Ndiaye , Quentin Gaignard Gaillard , Leo Bettoni ,
Nicolas Joly a c, Mbaye Diagne Mbaye a b, Albert Poater c, Sylvain Gaillard a,
,
,
Jean-Luc Renaud a
,
*
a
ꢀ
Normandie Univ., LCMT, ENSICAEN, UNICAEN, CNRS, 6 Boulevard Du Marechal Juin, 14050, Caen, France
Universite Assane Seck de Ziguinchor, BP 523, Ziguinchor, Senegal
Departament de Química, Institut de Química Computacional I Catalisi (IQCC), University of Girona, C/ M Aurelia Capmany 69, 17003, Girona, Catalonia,
b
c
ꢀ
a
ꢁ
ꢁ
Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
A Diaminocyclopentadienone iron tricarbonyl complex has been applied in chemoselective hydrogen
transfer reductions. This bifunctional iron complex demonstrated a broad applicability in mild conditions
in various reactions, such as reduction of aldehydes over ketones, reductive alkylation of various func-
Received 26 March 2021
Received in revised form
14 April 2021
Accepted 21 April 2021
Available online xxx
tionalized amines with functionalized aldehydes and reduction of
a,b-unsaturated ketones into the
corresponding saturated ketones. A broad range of functionalized substrates has been isolated in
excellent yields with this practical procedure.
© 2020 The Author(s). This is an open access article under the CC BY-NC-ND license (http://
creativecommons.org/licenses/by-nc-nd/4.0/).
Keywords:
Chemoselectivity
Iron complex
Reduction
Hydride transfer
1. Introduction
the discrimination between two different functions (i.e. alkene vs.
carbonyl) can appear manageable, this is much more problematical
Reduction reactions are a prominent process in organic syn-
thesis, both from an academic and an industrial point of view [1e8].
Metal-catalyzed syntheses of amines and alcohols have been
developed to prevent the use of stoichiometric amount of boro-
hydrides or aluminum hydrides, and consequently to diminish the
environmental impact [9e14]. These procedures reside in hydro-
genation and transfer hydrogenation (with isopropanol or formic
acid) and involve platinum complexes [9,10], and more recently
first-row transition metals [11e14]. Hydrogenation is the most
atom economical approach, but requires hydrogen gas handling
and consequently implies some safety issues. Hydrogen transfer
(TH) is an alternative pathway and a more practical tool in the
presence of alcohols, formic acid or formates as advantageous hy-
dride donors.
when the two reactive functions belong to the same class. Catalytic
chemoselective reductions of carbonyl functions over alkenes or
alkynes, or alkenes over carbonyl functions have been described in
literature with the presence of noble metals or earth-abundant
metals [17e19]. But the chemoselective reduction of aldehydes in
the presence of ketones has been underexamined [18b,20-24].
Dupau described in 2015 a general [Ru (diamine) (diphosphine)
(carboxylate)2] complex-catalyzed hydrogenation of aldehydes in
the presence of ketones [21]. More recently, very few examples of
such chemoselective reduction have been reported with
a
phosphine-containing iron complex, [22a] a pincer-type ligand
containing Earth-abundant metal complexes (Fe, [22b-d] Co [23],
Mn [24]) or a triaminocyclopentadienyl ancillary ligand [25]. Albeit
these works showed the feasibility with Earth-abundant metal
complexes, the scope was rather limited to some non-
functionalized aromatic carbonyl derivatives.
Iron-catalyzed transfer hydrogenation has received some
attention in the last ten years as a practical method for carbonyl and
imine reduction, including some enantioslective processes [22-23],
[26-30] Among the iron complexes, the bifunctional cyclo-
pentadienone iron carbonyl complexes presented several
The control of the chemoselectivity, which allows the differen-
tiation of functional groups, is a key factor in organic synthesis and
in fine chemistry. Indeed, it may shorten the syntheses as tedious
protection/deprotection steps can be then avoided [15,16]. While
* Corresponding author.
E-mail address: jean-luc.renaud@ensicaen.fr (J.-L. Renaud).
https://doi.org/10.1016/j.tet.2021.132187
0040-4020/© 2020 The Author(s). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Please cite this article as: S. Coufourier, D. Ndiaye, Q.G. Gaillard et al., Iron-catalyzed chemoselective hydride transfer reactions, Tetrahedron,
https://doi.org/10.1016/j.tet.2021.132187

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
Table 1
Optimization of the reaction conditions for aldehyde reduction.a.
advantages [28]. These pre-catalysts are easily synthesized, robust,
and stable and have been used in several hydrogenation reactions,
transfer hydrogenation, reductive aminations and alkylations
[28e30]. However, with the exception of the hydrogenation of a,b-
unsaturated aldehydes into allylic alcohols, no chemoselective re-
ductions has been described up to date with cyclopentadienone
iron carbonyl complexes. Following our ongoing interest in hy-
drogenation and hydrogen autotransfer technology [31,32], we
report a general chemoselective hydride transfer reduction of al-
dehydes over ketones, of enones into saturated ketones and a
chemoselective reductive alkylation of amines with aldehydes,
catalyzed by the diaminocyclopentadienone iron carbonyl complex
Fe (Scheme 1).
Entry HCO2X
Fe (mol%) Me3NO (mol%) T (ꢀC) Time (h) Conv. (%)b
1
2
3
4
5
6
HCO2H
HCO2NH4
HCO2Na
HCO2K
e
2
2
2
2
2
e
2.5
2.5
2.5
2.5
2.5
e
80
80
80
80
80
80
24
24
24
24
24
24
e
e
100
100
e
HCO2K
e
7
8
9
10
11
12
HCO2Kc
HCO2K
HCO2K
HCO2K
HCO2K
HCO2K
2
2
1
2
2
2
2.5
2.5
1.25
2.5
2.5
2.5
80
80
80
60
45
45
24
16
16
16
16
24
33
100
30
100
2. Results and discussion
First, the reduction of 4-methoxybenzaldehyde in the presence
of formic acid derivatives was chosen as a model reaction to opti-
mize the reaction conditions (Table 1). Various parameters such as
the temperature, the reaction time and the hydrogen donor were
scrutinized in this set of reactions (Table 1). The active species was
generated in situ from the air-stable Fe pre-catalyst, through the
addition of trimethylamine oxide (Me3NO) [33,34].
73
100 (99%)d
a
General conditions: HCO2X (5 mmol,
5 equiv.), 4-methoxybenzaldehyde
(1 mmol), pre-catalyst Fe (2 mol %), Me3NO (2.5 mol %), ethanol (2 mL).
b
Determined by 1H NMR spectroscopy.
3 equivalents.
Isolated yield.
c
d
No reaction was observed initially when formic acid or ammo-
nium formate was used (Entries 1e2, Table 1), while sodium and
potassium formate led to complete conversion within 24 h at 80 ꢀC
(Entries 3e4, Table 1). For solubility issues in ethanol, potassium
formate was used for this study. Whereas alcohols can be a source
of hydrogen in basic conditions in the presence of dia-
minocyclopentadienone iron tricarbonyl complexes [19d], ethanol
did not act as hydride donor in these conditions as no reduction was
observed without formate (Entry 5, Table 1). In the absence of iron
complex, no reduction occurred as well (Entry 6, Table 1).
Decreasing the amount of formate (from 5 to 3 equivalents) or the
catalyst loading led to lower conversions (entries 7 and 9, Table 1).
Shortening the reaction time from 24 to 16 h did not impede the
activity and the alcohol was isolated in full conversion (Entries 4
and 8, Table 1). Finally, the optimized conditions were the following
ones: 1 mmol of aldehyde in the presence of 5 equivalents of po-
tassium formate, 2 mol % of iron complex Fe, 2.5 mol % of Me3NO in
2
mL of ethanol at 45e60 ꢀC. In these conditions, the 4-
methoxybenzyl alcohol was isolated in 99% yield.
These conditions were applied to explore the scope of the
hydrogen transfer reduction of aromatic and aliphatic aldehydes 1
(Scheme 2). A variety of substituted benzaldehydes 1a-m were
initially introduced in this reduction. The corresponding alcohols
2a-m were prepared in excellent yields (75e99%, Scheme 2). Other
reducible functions such as nitro group, esters, nitrile, remained
untouched (compounds 2k-m). Halides were not reduced as well
(2i-j) and no hydrogenolysis of ethers was noticed (2a, 2c-f). Het-
eroaromatic aldehydes, such as pyridine carboxaldehydes 1n-p,
Scheme 2. Reduction of (hetero)aromatic and aliphatic aldehydes by hydride transfer
reaction with Fe.[a].
[a] General conditions: HCO2K (5 mmol, 5 equiv.), aldehyde 1 (1 mmol), pre-catalyst Fe
[b]
(2 mol %), Me3NO (2.5 mol %), ethanol (2 mL) at 45 ꢀC for 24 h
60 ꢀC.
Scheme 1. Layout of the chemoselective hydride transfer reduction with Fe.
2

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
thiophene carboxaldehyde 1r or furfural 1p, can be also used. The
corresponding alcohols 2n-r have been synthesized in 66e98%
yield (Scheme 2). The lower yields with the pyridine derivatives 2n-
p might be due to a possible coordination of the pyridine to the 16-
electron deficient iron centre [35]. Extension to the reduction of
aliphatic aldehydes 1s-v was also explored and the corresponding
alcohols 2s-v were obtained in excellent yields (97e99%, Scheme
2).
para position) or aliphatic aldehyde, such as 3-phenylpropanal 1v,
could be used with benzylamine 3a or aniline 3e. The corre-
sponding alkylated amines 4g-u have been prepared in 37e98%
yield (Scheme 3). Ether function on 4h and 4p-u, halide substituent
on 4m-n and 4t-u were tolerated as well as heteroaromatic ring
(4o) and N-benzyl anisidine derivatives 4p-u were isolated in
52e98% (Scheme 3).
In the same reaction conditions, no reduction or no reductive
amination of aliphatic or aromatic ketones was noticed. In a
competition reaction, when 4-methoxybenzaldehyde 1a and 4-
methyl acetophenone were engaged in reduction, 4-
methoxybenzyl alcohol 2a was isolated in full conversion and 97%
yield, when the ketone remained non-reactive (Scheme 4).
As the development of chemoselective reaction is crucial in
organic chemistry and because complete selectivity for aldehydes
toward ketones is still not fully explored [25], we undertook some
hydrogenation and reductive amination of ketoaldehydes (Scheme
5). As reported in Scheme 5, for this study, three keto-aldehydes 1y-
aa, being representative of the different classes of carbonyl com-
pounds, were introduced in reduction and reductive alkylation of
amines. The iron-catalyzed reduction of keto-aldehydes 1y-aa at
60 ꢀC in the presence of potassium formate provided exclusively
the keto-alcohols 2w-y in excellent yields (92e99%). Whatever the
aromatic or aliphatic carbonyl function, the aldehyde was chemo-
selectively reduced.
To emphasize the benefit of the chemoselective hydrogen
transfer methodology, we turned our attention to the reductive
alkylation of amines with keto-aldehydes 1y-aa. Quite surprisingly,
no report to date has appeared on the catalytic chemoselective
reductive amination with aldehydes under hydrogen transfer con-
ditions, while amines are important compounds in organic chem-
istry, chemical industry and biological processes, as well.
Remarkably, the same trend was observed in the reductive alkyl-
ation with amines. The functionalized amino-ketones 4v-ae were
synthesized in 35e80% yield from keto-aldehydes 1y-aa. Neither
reduction nor reductive amination of the ketone was detected by
1H NMR analysis of the crude mixture. With 4-acetylbenzaldehyde
1y, alkylated amines 4v-y were obtained in 48e80% yield (Scheme
5). Non protected alcohol, acetal and benzyl function were toler-
ated. The same conclusions could be drawn starting with 6-oxo-6-
phenyl-hexanal 1z and the corresponding amines 4z-ab were
produced in 59e78% yield (Scheme 5). With the more challenging
3(R)-(propen-20-yl)-6-oxo-heptanal 1aa, containing two aliphatic
carbonyl functions, highly functionalized aminoketones 4ac-ae
were synthesized in mild conditions in modest yields but with a
complete control of the chemoselectivity. The sole other products
were the remaining starting materials (Scheme 5).
Having established a simple protocol for the reduction of alde-
hydes, we thought to extend this work to the synthesis of
substituted amines. We have already demonstrated that cyclo-
pentadienone iron complexes were able to catalyze the reductive
alkylation of amines with aldehydes and ketones under hydrogen
pressure [32]. After a rapid optimization of the reaction conditions,
we found that Fe catalyzed the reductive alkylation of N-methyl
benzylamine 3a with citronellal 1s in the presence of 6.5 equiva-
lents of potassium formate at 80 ꢀC (Table S2 in ESI). The alkylated
amine 4a was obtained in 98% yield (Scheme 3 and Table S2). Both
aromatic and aliphatic amines 3b-f can be engaged in this reaction
without impeding the catalytic activities. Thus, tetrahy-
droisoquinoline 3b, functionalized N-methyl amines 3c-d, anisidine
3e and even the 2-aminopyridine 3f were engaged with citronellal
1s and the corresponding alkylated amines 4b-f were isolated in
65e80% yields (Scheme 3). To showcase the efficiency of this cat-
alytic system, N-methylethanolamine 3c and N-(methyl)amino
acetaldehyde dimethyl acetal 3d were alkylated with citronellal 1s
leading to 4c and 4d in 80 and 78% yields, respectively (Scheme 3).
The synthesis of amine 4f in 77% is quite remarkable as 2-
aminopyridine 3f is not often used in reductive amination. Other
benzaldehydes 1a-b, d, r, w-x (the last two having halide atoms in
Chemoselective hydrogenation of unsaturated carbonyl func-
tions, leading either to allylic alcohols or saturated ketones, has
been already reported with noble metal-based complexes [17].
Scheme 3. Reductive amination between aromatic and aliphatic aldehydes and amine
or aniline derivatives.[a]
Scheme 4. Chemoselective reduction.
[a]
[a]
General conditions: HCO2K (6.5 mmol, 6.5 equiv.), aldehyde 1 (1 mmol), amine 3
General conditions: HCO2K (5 mmol, 5 equiv.), aldehyde 1a (1 mmol), 4-
(2 mmol), pre-catalyst Fe (2 mol %), Me3NO (2.5 mol %), ethanol (2 mL), 80 ꢀC, 24 h [b]
methylacetophenone (1 mmol), pre-catalyst Fe (2 mol %), Me3NO (2.5 mol %),
48 h.
ethanol (2 mL) at 60 ꢀC for 24 h.
3

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
Scheme 6. Chemoselective C]C bond reduction of
a
,
b
-unsaturated ketones.
[a]
General conditions: HCO2K (5 mmol, 5 equiv.), enone 5 (1 mmol), pre-catalyst Fe
[b]
(2 mol %), Me3NO (2.5 mol %), ethanol (2 mL) at 45 ꢀC for 24 h
16 h.
Heteroaromatic chalcone type compounds, such as 2-thiophenyl 5i
and 2-furfuryl ketones 5h, furnished the saturated ketones 6h-i in
78e80%. The unprotected pyrrole compound 6j was prepared in an
excellent 98% yield. To emphasize the versatility of this method-
ology and to demonstrate its interest in synthesis, the scope was
broadened to trisubstituted unsaturated ketones 5k-t. Again,
whatever the nature of the substituent on the aromatic ring, the
presence of heterocyclic moiety, the ketones 6k-t were obtained in
30e97% yield. The reduction of progesterone 5t provided not only
chemoselectively but also diastereoselectively 6t in 30% yield. The
sole other product was the remaining starting material.
Scheme 5. Fe-Catalyzed chemoselective reduction and reductive alkylation of amines.
[a] General conditions for the chemoselective reduction of aldehydes: HCO2K (5 mmol,
5 equiv.), keto-aldehyde 1y-aa (1 mmol), pre-catalyst Fe (2 mol %), Me3NO (2.5 mol %),
ethanol (2 mL) at 60 ꢀC for 24 h [b] General conditions for the chemoselective reductive
amination: HCO2K (6.5 mmol, 6.5 equiv.), keto-aldehyde 1y-aa (1 mmol), amine 3
(2 mmol), pre-catalyst Fe (2 mol %), Me3NO (2.5 mol %), ethanol (2 mL), 80 ꢀC, 24 h.
Recently, some Earth-abundant metal complexes have been
described to reduce selectively
a,b-unsaturated aldehydes into
allylic alcohols [18], and enones into the corresponding saturated
ketones [19]. In iron chemistry, the first chemoselective reduction
of a,b-unsaturated ketones into the corresponding saturated ones
3. Conclusion
was reported by Bianchini with the iron hydride complex
[P4FeH(H2)]BPh4 (with P4 ¼ P(CH2CH2PPh3)3) in cyclopentanol as
hydrogen donor [36]. More recently, Bhanage used a combination
of FeSO4 and ethylenediaminetetraacetic acid disodium dihydrate
(EDTANa2.2H2O) in water at 100 ꢀC under 27.5 bar of hydrogen [37].
As the discrimination of various carbonyl functions was feasible
with the iron complex Fe, we thought to widen this work to the
We have described a general and easy-to-perform catalytic
system for the chemoselective reduction of aldehydes and a,b-un-
saturated ketones, and a chemoselective reductive alkylation of
amines. These results highlighted the versatility of the bifunctional
phosphine-free iron complex. The combination of dia-
minocyclopentadienone iron tricarbonyl complex (2 mol %) and
potassium formate allowed the reduction of a variety of aliphatic
and aromatic aldehydes (over ketones), of enones into ketones and
the reductive amination of aldehydes (over ketones) with func-
tionalized amines. This procedure is, up to date, one of the most
general technology for a chemoselective hydrogen transfer meth-
odology with an earth abundant metal-based complex.
chemoselective reduction of a,b-unsaturated carbonyl derivatives.
Substituted chalcone derivatives were first evaluated. Worth to
note is the unselective hydrogenation process with 5a. A mixture of
saturated ketone, allylic alcohol and saturated alcohol was
observed in a ratio depending on the reaction conditions (hydrogen
pressure and temperature). In sharp contrast, the alkene was
selectively reduced under transfer hydrogenation in basic condi-
tions (Scheme 6). Both electron-donating and electron-
withdrawing substituents on the aromatic rings were tolerated
and the corresponding ketones 6a-g were produced in 60e98%
yield. To illustrate the interest of the chemoselective transfer hy-
drogenation, 6b, bearing methoxy groups, was synthesized in 98%
yields when 6d having a nitro group was isolated in 60% yield. No
reduction of Csp2-Br bond was noticed in these conditions.
4. Experimental section
General Considerations: All reactions were carried out using
the Schlenk techniques under an atmosphere of dry Argon. Water
was degassed prior to use by bubbling argon gas directly in the
solvent. Other solvents were purchased from Carlo Erba and
degassed prior to use by freeze-pump thaw procedure (3 times).
NMR spectra were recorded on a 400 MHz and 500 MHz Brucker
4

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
spectrometer. Proton (1H) NMR information is given in the
following format: multiplicity: s, singlet; d, doublet; t, triplet; q,
quartet; quint, quintuplet; sept, septet; m, multiplet), coupling
constant(s) (J) in Hertz (Hz), number of protons. The prefix app is
occasionally applied when the true signal multiplicity was unre-
solved and br indicates the signal in question broadened. Carbon
potassium formate (5 equiv.) were added in ethanol (0.5 M) fol-
lowed by the addition of the iron complex Fe (2 mol%) and trime-
thylamine N-oxide (2.5 mol%). The mixture was heated at 45e60 ꢀC
for 24 h. After cooling-down to room temperature, the reaction
mixture was hydrolyzed with a saturated aqueous solution of so-
dium bicarbonate and extracted three times with ethyl acetate. The
organic phase was dried over MgSO4, filtrated and the solvent
evaporated in vacuo to give the crude product, which was purified
by flash chromatography.
NMR spectra are reported in ppm (d) relative to CDCl3 (d 77.16)
unless noted otherwise. HRMS analyses were performed by LCMT
analytical services. Neutral activated aluminium oxide was pur-
chased from Alfa Aesar (Brockmann Grade I, 58 Å, ꢁ60 Mesh
Powder, S.A. 150 m2/g) and from Merck (Grade I, 90 Å, 70e230
Mesh ASTM). Basic aluminium oxide was purchased from Alfa
Aesar (Brockmann GradeI, 58 Å, ꢁ60 Mesh Powder, S.A. 150 m2/g).
NMR solvents were filtered through a pad of basic alumina for NMR
analysis of iron complexes.
4.3. (4-methoxyphenyl)methanol (2a) [38]
Following the general procedure A, starting from 40-methox-
ybenzaldehyde (61
mL, 0.5 mmol), potassium formate (170 mg,
2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg, 0.0126 mmol)
at 45 ꢀC, alcohol 2a was obtained as a colorless oil (68 mg, 99%) after
purification by flash column chromatography on silica (eluent:
4.1. 6-Oxo-6-phenylhexanal (1z) [25]
pentane/AcOEt [80:20]). 1H NMR (500 MHz, CDCl3)
d: 7.30 (2H, d,
In a 100 mL roundbottom flask equipped with a stirring bar, 2-
phenylcyclohexene (3.18 mL, 20 mmol) was solubilized in dry
methylene chloride (50 mL) and cooled down to 0 ꢀC with an ice
bath. mCPBA (50% wt) (7.6 g, 22 mmol) was added slowly by
portion over 10 min. The reaction was stirred for 1 h at 0 ꢀC and
then quenched by a saturated aqueous solution of NaHCO3 (20 mL).
The organic phase was separated and the aqueous phase was
extracted twice with dichloromethane (2 ꢂ 20 mL). The organic
phases were combined, dried over MgSO4, filtered, and concen-
trated under vacuum. The crude product was purified by flash
column chromatography on silica (pentane/Et2O 95:5), and the
pure epoxide intermediate was then directly engaged in the next
step. The epoxide intermediate was solubilized in a 1/1 mixture of
THF/H2O (30 mL). Sodium periodate (30 mmol, 1.5 equiv, 6.41 g)
was added, and the reaction was stirred at room temperature for
18 h. The mixture was extracted with dichloromethane (3 ꢂ 20 mL),
and the organic layers were dried over Na2SO4, filtered, and
concentrated under vacuum. The crude product was purified by
flash column chromatography on silica (eluent: pentane/Et2O
[80:20]) and the pure ketoaldehyde 1z was obtained as a white
J ¼ 8.3 Hz), 6.90 (2H, d, J ¼ 8.3 Hz), 4.62 (2H, s), 3.81 (3H, s) (OH
signal not observed) ppm. 13C NMR (125 MHz, CDCl3)
128.7, 114.0, 65.1, 55.3 ppm.
d: 159.2,133.1,
4.4. Benzyl alcohol (2b)[38]
Following the general procedure A, starting from benzaldehyde
(51 mL, 0.5 mmol), potassium formate (210 mg, 2.5 mmol), Fe (5 mg,
0.01 mmol) and Me3NO (1 mg, 0.0126 mmol) at 45 ꢀC, alcohol 2b
was obtained as a colorless oil (53 mg, 98%) after purification by
flash column chromatography on silica (eluent: pentane/AcOEt
[80:20]). 1H NMR (500 MHz, CDCl3)
d
: 7.37 (4H, d, J ¼ 4.4 Hz),
7.33e7.29 (1H, m), 4.70 (2H, s), 1.70 (1H, s) ppm. 13C NMR (125 MHz,
CDCl3) : 140.9, 128.6, 127.7, 127.0, 65.4 ppm.
d
4.5. (2-methoxyphenyl)methanol (2c)[38]
Following the general procedure A, starting from 2-
methoxybenzaldehyde (68 mg, 0.5 mmol), potassium formate
(210 mg, 2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg,
0.0126 mmol) at 45 ꢀC, alcohol 2c was obtained as a colorless oil
(68 mg, 99%) after purification by flash column chromatography on
silica (eluent: pentane/AcOEt [90:10] then [70:30]). 1H NMR
solid (1.81 g, 48%). 1H NMR (500 MHz, CDCl3)
d: 9.78 (1H, s), 7.94
(2H, d, J ¼ 7.5 Hz), 7.56 (1H, t, J ¼ 6.7 Hz), 7.46 (2H, t, J ¼ 7.4 Hz), 3.00
(2H, t, J ¼ 6.8 Hz), 2.51 (1H, t, J ¼ 6.7 Hz), 2.42 (1H, t, J ¼ 7 Hz),
1.81e1.72 (1H, m) ppm. 13C NMR (125 MHz, CDCl3)
d: 199.9, 179.2,
(500 MHz, CDCl3)
d
: 7.30e7.26 (2H, m), 6.95 (1H, t, J ¼ 7.4 Hz), 6.90
136.9, 133.1, 128.6 (2C), 128.1 (2C), 38.1, 33.8, 24.3, 23.6 ppm.
(1H, d, J ¼ 8.0 Hz), 4.69 (2H, d, J ¼ 5.0 Hz), 3.88 (3H, s), 2.30 (1H, s)
ppm. 13C NMR (125 MHz, CDCl3)
62.3, 55.3 ppm.
d: 157.5, 129.0, 128.8, 120.7, 110.2,
4.2. (R)-6-Oxo-3-(prop-1-en-2-yl)heptanal (1aa) [25]
To a round-bottom flask was added a magnetic stir-bar, sodium
periodate (1.00 g, 4.7 mmol) and water (3 mL). The mixture was
stirred for 10 min, then THF (6 mL) and (ꢁ)-limonene oxide
(357 mg, 2.3 mmol) were added and stirred overnight. Upon re-
action completion, the iodate salts were filtered off and washed
with Et2O creating two distinct layers. The aqueous layer was
extracted (x3) with Et2O. The combined organic extracts were
washed with water and brine, dried over MgSO4, filtered, and
concentrated in vacuo. Ketoaldehyde 1aa was obtained as a color-
less liquid (275 mg, 70%) after purification by flash column chro-
matography on silica (eluent: pentane/Et2O [70:30] to [50:50]). 1H
4.6. (3-methoxyphenyl)methanol (2d)[38]
Following the general procedure A, starting from 3-
methoxybenzaldehyde (61
mL, 0.5 mmol), potassium formate
(210 mg, 2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg,
0.0126 mmol) at 60 ꢀC, alcohol 2d was obtained as a colorless liquid
(68 mg, 99%) after purification by flash column chromatography on
silica (eluent: pentane/AcOEt [90:10]). 1H NMR (500 MHz, CDCl3)
d:
7.29 (1H, t, J ¼ 7.9 Hz), 6.94 (2H, d, J ¼ 7.2 Hz), 6.84 (1H, d,
J ¼ 8.3 Hz), 4.68 (2H, s), 3.82 (3H, s), 1.66 (1H, s) ppm. 13C NMR
(125 MHz, CDCl3)
55.3 ppm.
d: 159.9, 142.5, 129.6, 119.1, 113.3, 112.3, 65.3,
NMR (500 MHz, CDCl3)
4.78e4.76 (1H, m), 2.71e2.65 (1H, m), 2.45 (2H, ddd, J ¼ 8.8, 7.5,
2.3 Hz), 2.39 (2H, t, J ¼ 7.5 Hz), 2.13 (3H, s), 1.76e1.69 (1H, m),
d
: 9.67 (1H, t, J ¼ 2.3 Hz), 4.84e4.82 (1H, m),
4.7. Piperonyl alcohol (2e)[38]
1.66e1.56 (4H, m) ppm. 13C NMR (125 MHz, CDCl3)
d: 208.3, 201.9,
145.1, 113.4, 47.5, 40.9, 40.8, 30.1, 26.4, 18.4 ppm.
Following the general procedure A, starting from piperonal
(75 mg, 0.5 mmol), potassium formate (210 mg, 2.5 mmol), Fe
(5 mg, 0.01 mmol) and Me3NO (1 mg, 0.0126 mmol) at 45 ꢀC,
alcohol 2e was obtained as a white solid (75 mg, 99%) after
General procedure A for chemoselective reduction of alde-
hydes or C ¼ C bond by hydrogen transfer reaction. In a dried
flamed Schlenk tube under argon, aldehyde or enone (1 equiv.) and
5

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
purification by flash column chromatography on silica (eluent:
ppm. 13C NMR (125 MHz, CDCl3)
127.1, 62.9 ppm.
d
: 138.2, 132.8, 129.4, 128.9, 128.8,
pentane/AcOEt [80:20]). 1H NMR (500 MHz, CDCl3)
d: 6.88 (1H, s),
6.80 (2H, q, J ¼ 7.9 Hz), 5.96 (2H, s), 4.59 (2H, s) (OH signal not
observed) ppm. 13C NMR (125 MHz, CDCl3)
120.5, 108.2, 107.9, 101.0, 65.3 ppm.
d: 147.9, 147.1, 134.9,
4.13. (4-nitrophenyl)methanol (2k)[38]
Following the general procedure A, starting from 4-
nitrobenzaldehyde (75 mg, 0.5 mmol), potassium formate
(210 mg, 2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg,
0.0126 mmol) at 45 ꢀC, alcohol 2k was obtained as a yellow powder
(75 mg, 98%) after purification by flash column chromatography on
4.8. (3,4,5-trimethoxyphenyl)methanol (2f)[38]
Following the general procedure A, starting from (3,4,5-
trimethoxy)benzaldehyde (98 mg, 0.5 mmol), potassium formate
(210 mg, 2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg,
0.0126 mmol) at 45 ꢀC, alcohol 2f was obtained as a thick colorless
oil (98 mg, 99%) purification by flash column chromatography on
silica (eluent: pentane/AcOEt [70:30]). 1H NMR (500 MHz, CDCl3)
d:
8.22 (2H, d, J ¼ 8.4 Hz), 7.54 (2H, d, J ¼ 8.4 Hz), 4.84 (2H, d,
J ¼ 5.6 Hz),1.91 (1H, t, J ¼ 5.6 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d:
silica (eluent: pentane/AcOEt [80:20]). 1H NMR (500 MHz, CDCl3)
d:
148.1, 147.3, 127.0, 123.8, 64.1 ppm.
6.60 (2H, s), 4.64 (2H, s), 3.87 (6H, s), 3.84 (3H, s), 1.72 (1H, s) ppm.
13C NMR (125 MHz, CDCl3)
56.1 ppm.
d: 153.4, 137.3, 136.6, 103.8, 65.6, 60.9,
4.14. (4-cyanophenyl)methanol (2l)[38]
Following the general procedure A, starting from 4-
cyanobenzaldehyde (65 mg, 0.5 mmol), potassium formate
(210 mg, 2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg,
0.0126 mmol) at 45 ꢀC, alcohol 2l was obtained as a white powder
(65 mg, 98%) after purification by flash column chromatography on
4.9. P-tolylmethanol (2g)[38]
Following the general procedure A, starting from 4-
methylbenzaldehyde (59 L, 0.5 mmol), potassium formate
m
(210 mg, 2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg,
0.0126 mmol) at 60 ꢀC, alcohol 2g was obtained as a white solid
(60 mg, 98%) purification by flash column chromatography on silica
silica (eluent: pentane/AcOEt [70:30]). 1H NMR (500 MHz, CDCl3)
d:
7.65 (2H, d, J ¼ 8.0 Hz), 7.48 (2H, d, J ¼ 8.0 Hz), 4.79 (2H, d,
J ¼ 3.3 Hz), 1.94 (1H, s) ppm. 13C NMR (125 MHz, CDCl3)
d: 146.1,
(eluent: pentane/AcOEt [80:20]). 1H NMR (500 MHz, CDCl3)
d: 7.19
132.4, 127.0, 118.9, 111.2, 64.3 ppm.
(2H, d, J ¼ 7.6 Hz), 7.10 (2H, d, J ¼ 7.6 Hz), 4.58 (2H, s), 2.28 (3H, s)
(OH signal not observed) ppm. 13C NMR (125 MHz, CDCl3)
137.4, 129.3, 127.1, 65.3, 21.2 ppm.
d: 137.9,
4.15. Ethyl 4-(hydroxymethyl)benzoate (2m)[38]
Following the general procedure A, starting from methyl 4-
formylbenzoate (82 mg, 0.5 mmol), potassium formate (210 mg,
2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg, 0.0126 mmol)
at 60 ꢀC, alcohol 1m was obtained as a colorless oil (88 mg, 98%)
after purification by flash column chromatography on silica (eluent:
4.10. (2,4,6-trimethylphenyl)methanol (2h)[38]
Following the general procedure A, starting from (2,4,6-
trimethyl)benzaldehyde (74 L, 0.5 mmol), potassium formate
m
(210 mg, 2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg,
0.0126 mmol) at 60 ꢀC, alcohol 2h was obtained as a white solid
(74 mg, 99%) purification by flash column chromatography on silica
pentane/Et2O [50:50]). 1H NMR (500 MHz, CDCl3)
d: 8.04 (2H, d,
J ¼ 8.3 Hz), 7.43 (1H, d, J ¼ 8.3 Hz), 4.78 (2H, d, J ¼ 4.7 Hz), 4.38 (2H,
q, J ¼ 7.1 Hz), 1.81 (1H, t, J ¼ 5.2 Hz), 1.40 (3H, t, J ¼ 7.1 Hz) ppm. 13
C
(eluent: pentane/AcOEt [80:20]). 1H NMR (500 MHz, CDCl3)
d
: 6.87
NMR (125 MHz, CDCl3)
14.4 ppm.
d: 166.5, 145.8, 129.8, 129.7, 126.5, 64.8, 61.0,
(2H, s), 4.71 (2H, s), 2.40 (6H, s), 2.27 (3H, s), 1.18 (1H, s) ppm. 13
C
NMR (125 MHz, CDCl3)
19.4 ppm.
d: 137.8, 137.3, 133.7, 129.2, 59.2, 21.0,
4.16. Pyridin-2-ylmethanol (2n)[38]
4.11. (2-bromophenyl)methanol (2i)[38]
Following the general procedure A, starting from 2-
pyridinecarboxaldehyde (48 L, 0.5 mmol), potassium formate
(210 mg, 2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg,
0.0126 mmol) at 60 ꢀC, alcohol 2n was obtained as a colorless oil
(48 mg, 88%) after purification by flash column chromatography on
silica (eluent: AcOEt to AcOEt/MeOH [95:5]). 1H NMR (500 MHz,
m
Following the general procedure A, starting from 2-
bromobenzaldehyde (58 L, 0.5 mmol), potassium formate
m
(170 mg, 2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg,
0.0126 mmol) at 60 ꢀC, alcohol 2i was obtained as a white powder
(70 mg, 75%) after purification by flash column chromatography on
silica (eluent: pentane/AcOEt [70:30]). 1H NMR (500 MHz, CDCl3)
d:
CDCl3)
d
: 8.55 (1H, d, J ¼ 4.7 Hz), 7.68 (1H, t, J ¼ 7.8 Hz), 7.25 (1H, d,
J ¼ 7.8 Hz), 7.20 (1H, t, J ¼ 4.7 Hz), 4.76 (2H, s), 3.95 (1H, s) ppm. 13
C
7.55 (1H, d, J ¼ 7.6 Hz), 7.48 (1H, d, J ¼ 7.6 Hz), 7.34 (1H, t, J ¼ 7.6 Hz),
NMR (125 MHz, CDCl3) d: 159.0, 148.5, 136.7, 122.4, 120.5, 64.1 ppm.
7.17 (1H, t, J ¼ 7.6 Hz), 4.76 (2H, d, J ¼ 5.8 Hz), 1.97 (1H, t, J ¼ 5.8 Hz)
ppm. 13C NMR (125 MHz, CDCl3)
122.6, 65.1 ppm.
d: 139.7, 132.6, 129.2, 128.9, 127.7,
4.17. Pyridin-3-ylmethanol (2o)[38]
4.12. (2-chlorophenyl)methanol (2j)[38]
Following the general procedure A, starting from 3-
pyridinecarboxaldehyde (47 L, 0.5 mmol), potassium formate
m
Following the general procedure A, starting from 2-
(210 mg, 2.5 mmol), Fe (9 mg, 0.01 mmol) and Me3NO (1 mg,
0.0126 mmol) at 60 ꢀC, alcohol 1o was obtained as a colorless oil
(40 mg, 73%) after purification by flash column chromatography on
silica (eluent: AcOEt to AcOEt/MeOH [95:5]). 1H NMR (500 MHz,
chlorobenzaldehyde (56
mL, 0.5 mmol), potassium formate
(210 mg, 2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg,
0.0126 mmol) at 60 ꢀC, alcohol 2j was obtained as a white powder
(93 mg, 99%) after purification by flash column chromatography on
CDCl3)
d
: 8.55 (1H, s), 8.50 (1H, d, J ¼ 3.8 Hz), 7.73 (1H, d, J ¼ 7.7 Hz),
silica (eluent: pentane/AcOEt [70:30]). 1H NMR (500 MHz, CDCl3)
d
:
7.29 (1H, dd, J ¼ 7.5, 5.0 Hz), 4.73 (2H, s) (OH signal not observed)
7.48 (1H, d, J ¼ 7.4 Hz), 7.37 (1H, d, J ¼ 7.4 Hz), 7.29 (1H, t, J ¼ 7.4 Hz),
ppm. 13C NMR (125 MHz, CDCl3)
62.6 ppm.
d: 148.8, 148.4, 136.4, 134.9, 123.6,
7.24 (1H, t, J ¼ 7.4 Hz), 4.79 (2H, d, J ¼ 6.2 Hz), 1.93 (1H, t, J ¼ 6.2 Hz)
6

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
4.18. Pyridin-4-ylmethanol (2p)[38]
without purification. 1H NMR (500 MHz, CDCl3)
d: 3.44 (2H, d,
J ¼ 6.4 Hz), 1.76e1.72 (4H, m), 1.69e1.66 (1H, m), 1.51e1.43 (1H, m),
Following the general procedure A, starting from 4-
1.27e1.14 (3H, m), 0.97e0.88 (2H, m) (OH signal not observed)
pyridinecarboxaldehyde (47
mL, 0.5 mmol), potassium formate
ppm. 13C NMR (125 MHz, CDCl3)
d: 68.8, 40.5, 29.6, 26.6, 25.8 ppm.
(210 mg, 2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg,
0.0126 mmol) at 60 ꢀC, alcohol 2p was obtained as a white powder
(36 mg, 66%) after purification by flash column chromatography on
silica (eluent: AcOEt to AcOEt/MeOH [90:10]). 1H NMR (500 MHz,
4.24. 3-Phenylpropan-1-ol (2v)[38]
Following the general procedure A, starting from 3-
phenylpropanal (66 L, 0.5 mmol), potassium formate (210 mg,
CDCl3)
d
: 8.49 (2H, d, J ¼ 4.8 Hz), 7.29 (2H, d, J ¼ 4.8 Hz), 4.74 (2H, s)
m
(OH signal not observed) ppm. 13C NMR (125 MHz, CDCl3)
149.5, 121.2, 63.1 ppm.
d: 150.8,
2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg, 0.0126 mmol)
at 60 ꢀC, alcohol 2v was obtained as a colorless oil (67 mg, 99%) after
purification by flash column chromatography on silica (eluent:
4.19. Thiophen-2-ylmethanol (2q)[38]
pentane/AcOEt [90:10] to [70:30]). 1H NMR (500 MHz, CDCl3)
d:
7.31e7.28 (2H, m), 7.22e7.18 (3H, m), 3.69 (2H, app t, J ¼ 6.1 Hz),
Following the general procedure A, starting from 2-
thiophenecarboxaldehyde (47 L, 0.5 mmol), potassium formate
2.72 (2H, app t, J ¼ 6.1 Hz), 1.93e1.88 (2H, m), 1.25 (1H, s) ppm. 13
C
m
NMR (125 MHz, CDCl3)
32.1 ppm.
d: 141.8, 128.5, 128.4, 126.9, 62.3, 34.2,
(210 mg, 2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg,
0.0126 mmol) at 60 ꢀC, alcohol 2q was obtained as a colorless oil
(56 mg, 98%) after purification by flash column chromatography on
4.25. 1-(4-(hydroxymethyl)phenyl)ethan-1-one (2w) [39]
silica (eluent: pentane/AcOEt [70:30]). 1H NMR (500 MHz, CDCl3)
d:
7.29 (1H, d, J ¼ 5.0 Hz), 7.02 (1H, s), 6.98 (1H, t, J ¼ 4.0 Hz), 4.84 (2H,
Following the general procedure A, starting from (4-acetyl)
benzaldehyde (73 mg, 0.5 mmol), potassium formate (210 mg,
2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg, 0.0126 mmol)
at 60 ꢀC, alcohol 2w was obtained as a white solid (73 mg, 97%) after
purification by flash column chromatography on silica (eluent:
s), 1.83 (1H, s) ppm. 13C NMR (125 MHz, CDCl3)
126.5, 60.1 ppm.
d: 144.0,126.9,126.7,
4.20. Furan-2-ylmethanol (2r)[38]
pentane/AcOEt [50:50]). 1H NMR (500 MHz, CDCl3)
d: 7.96 (2H, d,
Following the general procedure A, starting from furfural (41
m
L,
J ¼ 7.7 Hz), 7.46 (2H, d, J ¼ 7.7 Hz), 4.78 (2H, s), 2.61 (3H, s), 1.84 (1H,
0.5 mmol), potassium formate (210 mg, 2.5 mmol), Fe (5 mg,
0.01 mmol) and Me3NO (1 mg, 0.0126 mmol) at 60 ꢀC, alcohol 2r
was obtained as a yellow oil (48 mg, 98%) after purification by flash
column chromatography on silica (eluent: pentane/AcOEt [70:30]).
s) ppm. 13C NMR (125 MHz, CDCl3)
126.6, 64.7, 26.7 ppm.
d: 197.9, 146.2, 136.4, 128.7,
4.26. 6-Hydroxy-1-phenylhex-1-one (2x) [40]
1H NMR (500 MHz, CDCl3)
d
: 7.40 (1H, dd, J ¼ 1.9, 0.8 Hz), 6.34 (1H,
dd, J ¼ 3.2, 1.9 Hz), 6.30 (1H, d, J ¼ 3.2 Hz), 4.61 (2H, s), 1.76 (1H, s)
Following the general procedure A, starting from ketoaldehyde
1z (95 mg, 0.5 mmol), potassium formate (210 mg, 2.5 mmol), Fe
(5 mg, 0.01 mmol) and Me3NO (1 mg, 0.0126 mmol) at 60 ꢀC,
alcohol 2x was obtained as a yellow oil (40 mg, 42%) after purifi-
cation by flash column chromatography on silica (eluent: pentane/
ppm. 13C NMR (125 MHz, CDCl3)
57.5 ppm.
d: 153.9, 142.6, 110.4, 107.8,
4.21. Citronellol (2s)[38]
AcOEt [80:20]). 1H NMR (500 MHz, CDCl3)
d
: 7.97 (2H, d, J ¼ 7.7 Hz),
Following the general procedure A, starting from citronellal
7.55 (1H, t, J ¼ 7.3 Hz), 7.45 (2H, t, J ¼ 7.4 Hz), 3.66 (2H, t, J ¼ 6.2 Hz),
2.99 (2H, t, J ¼ 7.2 Hz), 1.77 (2H, quint, J ¼ 7.5 Hz), 1.62 (2H, quint,
J ¼ 7.2 Hz), 1.46 (2H, quint, J ¼ 7.5 Hz) ppm. 13C NMR (125 MHz,
(90 mL, 0.5 mmol), potassium formate (210 mg, 2.5 mmol), Fe (5 mg,
0.01 mmol) and Me3NO (1 mg, 0.0126 mmol) at 60 ꢀC, alcohol 2s
was obtained as a colorless oil (77 mg, 99%) without purification. 1H
CDCl3) d: 200.4, 137.0, 133.0, 128.6, 128.1, 62.7, 38.5, 32.5, 25.5,
NMR (500 MHz, CDCl3)
d
: 5.09 (1H, app t, J ¼ 7.2 Hz), 3.67e3.55 (2H,
23.9 ppm.
m), 2.00e1.82 (2H, m), 1.62 (3H, s), 1.60e1.45 (5H, m), 1.38e1.22
(2H, m), 1.19e1.06 (2H, m), 0.90 (3H, d, J ¼ 7.2 Hz) ppm. 13C NMR
4.27. (R)-5-(2-hydroxyethyl)-6-methylhept-6-en-2-one (2y) [41]
(125 MHz, CDCl3)
19.5, 17.7 ppm.
d: 131.3, 124.7, 61.2, 39.9, 37.2, 29.2, 25.7, 25.5,
Following the general procedure A, starting from ketoaldehyde
1aa (84 mg, 0.5 mmol), potassium formate (210 mg, 2.5 mmol), Fe
(5 mg, 0.01 mmol) and Me3NO (1 mg, 0.0126 mmol) at 60 ꢀC,
alcohol 2y was obtained as a colorless oil (78 mg, 92%) after puri-
fication by flash column chromatography on silica (eluent:
4.22. 3,7-Dimethyloctane-1,7-diol (2t)[38]
Following the general procedure A, starting from 7-
hydroxycitronellal (93
mL, 0.5 mmol), potassium formate (210 mg,
pentane/AcOEt [70:30] to [50:50]). 1H NMR (500 MHz, CDCl3)
d:
2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg, 0.0126 mmol)
4.80 (1H, s), 4.74 (1H, s), 3.64e3.58 (2H, m), 2.36 (2H, t, J ¼ 7.5 Hz),
at 60 ꢀC, diol 2t was obtained as a thick colorless oil (86 mg, 99%)
2.22e2.17 (1H, m), 2.12 (3H, s), 1.70e1.55 (7H, m), 1.46 (1H, s) ppm.
without purification. 1H NMR (500 MHz, CDCl3)
d: 3.73e3.64 (2H,
13C NMR (125 MHz, CDCl3)
30.1, 26.6, 17.5 ppm.
d: 209.1,146.7,112.9, 61.3, 43.6, 41.4, 36.1,
m), 1.64e1.57 (2H, m), 1.44e1.31 (8H, m), 1.21 (6H, s), 1.17e1.13 (1H,
m), 0.90 (3H, d, J ¼ 6.6 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d: 71.1,
General procedure B for reductive amination by hydrogen
transfer reaction. In a flamed dried Schlenk under an argon at-
mosphere containing a stirring bar was charged the aldehyde (1
equiv.), amine (2 equiv.), potassium formate (6.5 equiv.), iron
complex (2 mol%) and trimethylamine N-oxide (2.5 mol%) in
ethanol (1 mL). The reaction mixture was heated at 80 ꢀC for
24e48 h. After cooling-down to room temperature, the reaction
mixture was quenched with a saturated aqueous solution of
NaHCO3 and the organic layer was extracted twice with AcOEt and
61.2, 44.1, 39.9, 37.6, 29.5, 29.4, 29.2, 21.7, 19.6 ppm.
4.23. Cyclohexylmethanol (2u)[38]
Following the general procedure A, starting from cyclohexane
carboxaldehyde (60 L, 0.5 mmol), potassium formate (210 mg,
m
2.5 mmol), Fe (5 mg, 0.01 mmol) and Me3NO (1 mg, 0.0126 mmol)
at 60 ꢀC, alcohol 2u was obtained as a clear yellow oil (55 mg, 97%)
7

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
washed with water. Combined organic layer was dried over MgSO4
and concentrated under reduced pressure to afford the crude
product that was purified by silica gel column chromatography.
Pentane/Et2O [90:10] to [70:30]). 1H NMR (500 MHz, CDCl3)
d: 5.09
(1H, t, J ¼ 7.0 Hz), 4.49 (1H, t, J ¼ 5.0 Hz), 3.36 (6H, s), 2.54e2.47 (2H,
m), 2.46e2.39 (2H, m), 2.29 (3H, s), 2.04e1.88 (2H, m), 1.67 (3H, s),
1.59 (3H, s), 1.56e1.48 (1H, m), 1.46e1.38 (1H, m), 1.36e1.25 (2H,
m), 1.19e1.12 (1H, m), 0.88 (3H, d, J ¼ 6.6 Hz) ppm. 13C NMR
4.28. N-benzyl-N,3,7-trimethyloct-6-en-1-amine (4a) [25]
(125 MHz, CDCl3) d: 131.1, 124.9, 102.8, 58.9, 56.6, 53.3, 43.3, 37.3,
Following the general procedure B, starting from citronellal
34.0, 30.9, 25.7, 25.5, 19.7, 17.7 ppm.
(91
mL, 0.5 mmol), N-methylbenzylamine (150 mL, 1 mmol), Fe
(5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium
formate (273 mg, 3.25 mmol) for 16 h at 80 ꢀC, the corresponding
amine 4a was obtained as a yellow oil (127 mg, 98%) after purifi-
cation by flash column chromatography on silica (eluent: CH2Cl2/
4.32. N-(3,7-dimethyloct-6-en-1-yl)-4-methoxyaniline (4e) [32a]
Following the general procedure B, starting from citronellal
(91
mL, 0.5 mmol), p-anisidine (123 mg, 1 mmol), Fe (5 mg,
MeOH [99:1]). 1H NMR (500 MHz, CDCl3)
d
: 7.31 (4H, d, J ¼ 4.4 Hz),
0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium formate
(273 mg, 3.25 mmol) for 16 h at 80 ꢀC, the corresponding amine 4e
was obtained as a yellow oil (101 mg, 77%) after purification by flash
column chromatography on silica (eluent: pentane/AcOEt [95:5] to
7.26e7.22 (1H, m), 5.09 (1H, t, J ¼ 7.1 Hz), 3.48 (2H, q, J ¼ 13.0 Hz),
2.39 (2H, t, J ¼ 7.5 Hz), 2.18 (3H, s), 2.04e1.90 (2H, m), 1.68 (3H, s),
1.60 (3H, s), 1.58e1.55 (1H, m), 1.50e1.46 (1H, m), 1.34e1.29 (2H,
m), 1.19e1.11 (1H, m), 0.87 (3H, d, J ¼ 6.6 Hz) ppm. 13C NMR
[90:10]). 1H NMR (500 MHz, CDCl3)
d
: 6.78 (2H, d, J ¼ 8.6 Hz), 6.58
(125 MHz, CDCl3)
d
: 139.3,131.1, 129.1, 128.2, 126.9, 124.9, 62.4, 55.6,
(2H, d, J ¼ 8.6 Hz), 5.10 (1H, t, J ¼ 6.6 Hz), 3.75 (3H, s), 3.37 (1H, s),
3.13e3.05 (2H, m), 2.05e1.93 (2H, m), 1.69 (3H, s), 1.67e1.54 (5H,
m), 1.46e1.34 (2H, m), 1.26e1.17 (1H, m), 0.94 (3H, d, J ¼ 6.5 Hz)
42.3, 37.3, 34.4, 30.9, 25.8, 25.5, 19.7, 17.7 ppm.
4.29. 2-(3,7-Dimethyloct-6-en-1-yl)-1,2,3,4-tetrahydroisoquinoline
ppm. 13C NMR (125 MHz, CDCl3)
d: 151.9, 142.8, 131.4, 124.7, 114.9,
(4b) [25]
114.1, 55.9, 43.0, 37.1, 36.8, 30.5, 25.8, 25.5, 19.6, 17.7 ppm.
Following the general procedure B, starting from citronellal
4.33. N-(3,7-dimethyloct-6-enyl)pyridin-2-amine (4f)
(91 mL, 0.5 mmol), 1,2,3,4-tetrahydroisoquinoline (126 mL, 1 mmol),
Fe (5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium
formate (273 mg, 3.25 mmol) for 24 h at 80 ꢀC, the corresponding
amine 4b was obtained as a yellow oil (88 mg, 65%) after purifi-
cation by flash column chromatography on silica (eluent: pentane/
Following the general procedure B, starting from citronellal
(90 mL, 0.5 mmol), 2-aminopyridine (94 mg, 1 mmol), Fe (5 mg,
0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium formate
(273 mg, 3.25 mmol) for 48 h at 80 ꢀC, the corresponding amine 4f
was obtained as a yellow oil (114 mg, 98%) after purification by flash
column chromatography on silica (eluent: CH2Cl2/MeOH [95:5]).
hmax (liquid film) 3340, 3210, 2960, 2915, 2856, 2042, 1980, 1605,
1570, 1488, 1443, 1377, 1324, 1288, 1152, 1056, 988, 829, 770, 736,
AcOEt [95:5] to [90:10]). 1H NMR (500 MHz, CDCl3)
d: 7.12e7.08
(3H, m), 7.03e7.01 (1H, m), 5.11 (1H, t, J ¼ 7.1 Hz), 3.62 (2H, s), 2.91
(2H, t, J ¼ 5.9 Hz), 2.73 (2H, td, J ¼ 6.0, 3.0 Hz), 2.52 (2H, dt, J ¼ 9.5,
5.6 Hz), 2.06e1.93 (2H, m), 1.69 (3H, s), 1.67e1.63 (1H, m), 1.61 (3H,
s), 1.55e1.48 (1H, m),1.45e1.33 (2H, m),1.29e1.17 (1H, m), 0.93 (3H,
700, 521 cmꢁ1.1H NMR (500 MHz, CDCl3)
d
: 8.05 (1H, d, J ¼ 4.9 Hz),
d, J ¼ 6.6 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d
: 135.0, 134.4, 131.2,
7.42 (1H, t, J ¼ 7.7 Hz), 6.64 (1H, t, J ¼ 6.1 Hz), 6.50 (1H, d, J ¼ 8.3 Hz),
5.09 (1H, t, J ¼ 6.8 Hz), 4.44 (1H, br s (NH)), 3.72e3.63 (2H, m),
2.04e1.91 (2H, m), 1.68 (3H, s), 1.60 (3H, s), 1.58e1.53 (1H, m),
1.41e1.30 (2H, m), 1.26e1.24 (1H, m), 1.20e1.13 (1H, m), 0.90 (3H, d,
128.7, 126.6, 126.1, 126.6, 124.9, 56.6, 56.4, 51.1, 37.3, 34.3, 31.2, 29.2,
25.7, 25.5, 19.8, 17.7 ppm.
4.30. 2-(N-methyl-N-3,7-dimethyloct-6-enyl)amino)ethanol (4c)
J ¼ 6.5 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d: 158.4, 148.1, 137.8,
131.3, 124.7, 114.1, 108.6, 61.2, 40.0, 37.2, 29.2, 25.7, 25.5, 19.5,
17.7 ppm. HRMS: MHþ, found: 233.2016. C15H25N2 requires
233.2018.
Following the general procedure B, starting from citronellal
(90
mL, 0.5 mmol), N-methylethanolamine (61.2 mL, 1 mmol), Fe
(5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium
formate (273 mg, 3.25 mmol) for 48 h at 80 ꢀC, the corresponding
amine 4c was obtained as a colorless oil (85 mg, 80%) after purifi-
cation by flash column chromatography on silica (eluent: CH2Cl2/
MeOH [90:10] to [70:30]). hmax (liquid film) 3353, 2922, 2853,
2799, 1455, 1376, 1042, 937, 878, 821 cmꢁ1.1H NMR (500 MHz,
4.34. N-benzyl-N-methyl-3-phenylpropan-1-amine (4g) [32b]
Following the general procedure B, starting from hydro-
cinnamaldehyde (66 mL, 0.5 mmol), N-methylbenzylamine (150 mL,
1 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and
potassium formate (273 mg, 3.25 mmol) for 48 h at 80 ꢀC, the
corresponding amine 4g was obtained as a colorless oil (44 mg,
37%) after purification by flash column chromatography on silica
(eluent: pentane/AcOEt [95:5] to [90:10]). 1H NMR (500 MHz,
CDCl3)
d
: 5.08 (1H, t, J ¼ 7.0 Hz), 3.64 (2H, t, J ¼ 5.2 Hz), 2.61 (2H, t,
J ¼ 5.2 Hz), 2.53e2.50 (2H, m), 2.33 (3H, s), 2.04e1.90 (2H, m), 1.68
(3H, s), 1.60 (3H, s), 1.58e1.51 (1H, m), 1.50e1.42 (1H, m), 1.37e1.29
(2H, m), 1.28e1.25 (1H, m), 1.20e1.13 (1H, m), 0.89 (3H, d,
J ¼ 6.5 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d: 131.4, 124.6, 59.0,
CDCl3)
d
: 7.24 (3H, d, J ¼ 4.2 Hz), 7.19 (4H, m), 7.10 (3H, d, J ¼ 7.2 Hz),
58.0, 55.8, 41.5, 37.1, 33.7, 30.6, 25.7, 25.6, 19.6, 17.7 ppm. HRMS:
MHþ, found: 214.2168. C13H28NO requires 214.2171.
3.41 (2H, s), 2.57 (2H, t, J ¼ 7.8 Hz), 2.35 (2H, t, J ¼ 7.8 Hz), 2.12 (3H,
s), 1.77 (2H, quint, J ¼ 7.8 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d:
142.5,139.3,129.2,129.1,128.5,128.4,128.3,128.2,126.9,126.7, 62.3,
56.9, 42.2, 33.6, 29.2 ppm.
4.31. (2,2 dimethoxyethyl) (3,7 dimethyloct-6-en-1-yl)methylamine
(4d) [25]
4.35. 4-Methoxy-N-(3-phenylpropyl)aniline (4h) [42]
Following the general procedure B, starting from citronellal
(90
(99
m
L, 0.5 mmol), N-methylaminoacetaldehyde dimethyl acetal
Following the general procedure B, starting from hydro-
cinnamaldehyde (66 mL, 0.5 mmol), p-anisidine (123 mg, 1 mmol),
Fe (5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium
formate (273 mg, 3.25 mmol) for 48 h at 80 ꢀC, the corresponding
amine 4h was obtained as a yellow oil (115 mg, 95%) after
mL, 1 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol)
and potassium formate (273 mg, 3.25 mmol) for 48 h at 80 ꢀC, the
corresponding amine 4d was obtained as a yellow oil (100 mg, 78%)
after purification by flash column chromatography on silica (eluent:
8

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
purification by flash column chromatography on silica (eluent:
4.40. N-benzyl-1-(4-chlorophenyl)-N-methylmethanamine (4m)
pentane/AcOEt [95:5] to [90:10]). 1H NMR (500 MHz, CDCl3)
d: 7.30
(2H, t, J ¼ 7.4 Hz), 7.22 (3H, d, J ¼ 6.3 Hz), 6.79 (2H, d, J ¼ 8.5 Hz),
6.56 (2H, d, J ¼ 8.5 Hz), 3.76 (3H, s), 3.12 (2H, t, J ¼ 7.1 Hz), 2.74 (2H,
t, J ¼ 7.1 Hz), 1.95 (2H, quint., J ¼ 7.1 Hz) (NH signal not observed)
Following the general procedure B, starting from 4-
chlorobenzaldehyde (70 mg, 0.5 mmol), N-methylbenzylamine
(150
mL, 1 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
ppm. 13C NMR (125 MHz, CDCl3)
d
: 152.0, 142.7, 141.8, 128.5, 128.4,
0.0126 mmol) and potassium formate (273 mg, 3.25 mmol) for 48 h
at 80 ꢀC, the corresponding amine 4m was obtained as a yellow oil
(44 mg, 36%) after purification by flash column chromatography on
silica (eluent: pentane/AcOEt [95:5] to [90:10]). hmax (liquid film)
3028, 2924, 2840, 2786, 1598, 1490, 1452, 1406, 1364, 1284, 1263,
1240, 1192, 1132, 1088, 1025, 1015, 979, 939, 908, 867, 838, 799, 737,
126.9, 114.9, 114.1, 55.9, 44.5, 33.5, 31.2 ppm.
4.36. N-benzyl-N-methyl-1-phenylmethanamine (4i) [32c]
Following the general procedure B, starting from benzaldehyde
(51
mL, 0.5 mmol), N-methylbenzylamine (150
mL, 1 mmol), Fe
697, 671, 634, 611, 536, 488, 456 cmꢁ1.1H NMR (500 MHz, CDCl3)
7.32e7.21 (10H, m), 3.48 (2H, s), 3.45 (2H, s), 2.14 (3H, s) ppm. 13
NMR (125 MHz, CDCl3)
128.3, 127.1, 61.9, 61.1, 42.2 ppm. HRMS: MHþ, found: 246.1052.
15H17NCl requires 246.1050.
d:
(5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium
formate (273 mg, 3.25 mmol) for 48 h at 80 ꢀC, the corresponding
amine 4i was obtained as a yellow oil (97 mg, 92%) after purification
by flash column chromatography on silica (eluent: pentane/AcOEt
C
d: 139.1, 137.9, 132.6, 130.2, 128.9, 128.4,
C
[97:3]). 1H NMR (500 MHz, CDCl3)
d
: 7.37 (4H, d, J ¼ 7.4 Hz), 7.32
(4H, t, J ¼ 7.4 Hz), 7.25 (2H, t, J ¼ 7.4 Hz), 3.53 (4H, s), 2.19 (3H, s)
4.41. N-benzyl-1-(4-fluorophenyl)-N-methylmethanamine (4n)
[38]
ppm. 13C NMR (125 MHz, CDCl3)
42.3 ppm.
d: 139.4, 128.9, 128.2, 126.9, 61.9,
Following the general procedure B, starting from 4-
4.37. N-benzyl-1-(4-methoxyphenyl)-N-methylmethanamine (4j)
[32c]
fluorobenzaldehyde (54
mL, 0.5 mmol), N-methylbenzylamine
(150 L, 1 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
m
0.0126 mmol) and potassium formate (273 mg, 3.25 mmol) for 24 h
at 80 ꢀC, the corresponding amine 4n was obtained as a yellow oil
(69 mg, 60%) after purification by flash column chromatography on
silica (eluent: pentane/AcOEt [95:5] to [90:10]). 1H NMR (500 MHz,
Following the general procedure B, starting from p-anisaldehyde
(61
mL, 0.5 mmol), N-methylbenzylamine (150 mL, 1 mmol), Fe
(5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium
formate (273 mg, 3.25 mmol) for 48 h at 80 ꢀC, the corresponding
amine 4j was obtained as a yellow oil (116 mg, 96%) after purifi-
cation by flash column chromatography on silica (eluent: pentane/
CDCl3)
d: 7.28e7.23 (6H, m), 7.18e7.16 (1H, m), 6.92 (2H, t,
J ¼ 8.3 Hz), 3.43 (2H, s), 3.40 (2H, s), 2.09 (3H, s) ppm. 13C NMR
(125 MHz, CDCl3) d: 162.9, 161.0, 139.2, 135.1, 130.4, 130.3, 128.9,
AcOEt [95:5] to [90:10]). 1H NMR (500 MHz, CDCl3)
d
: 7.28e7.15
(7H, m), 6.80 (2H, t, J ¼ 5.7 Hz), 3.73 (3H, s), 3.42 (2H, s), 3.39 (2H, s),
2.09 (3H, s) ppm. 13C NMR (125 MHz, CDCl3)
: 158.7, 139.4, 131.4,
128.3, 127.0, 115.1, 114.9, 61.9, 61.1, 42.2 ppm. 19F NMR (500 MHz,
CDCl3) : 116.16 ppm.
d
d
130.1, 128.9, 128.2, 126.9, 113.6, 61.7, 61.3, 55.3, 42.1 ppm.
4.42. N-benzyl-N-methyl-1-(thiophen-2-yl)methanamine (4o)
4.38. N-benzyl-1-(3-methoxyphenyl)-N-methylmethanamine (4k)
[32c]
Following the general procedure B, starting from 2-
thiophenecarboxaldehyde (47
mL, 0.5 mmol), N-methylbenzyl-
amine (150 L, 1 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
m
Following the general procedure B, starting from m-anisalde-
0.0126 mmol) and potassium formate (273 mg, 3.25 mmol) for 48 h
at 80 ꢀC, the corresponding amine 4o was obtained as a yellow oil
(107 mg, 98%) after purification by flash column chromatography
on silica (eluent: pentane/AcOEt [95:5] to [90:10]); hmax (liquid
film) 3027, 2924, 2837, 2785, 1495, 1452, 1418, 1366, 1340, 1277,
1263,1222,1168, 1130, 1075, 1023, 973, 908, 863, 820, 736, 694, 606,
hyde (61 mL, 0.5 mmol), N-methylbenzylamine (150 mL, 1 mmol), Fe
(5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium
formate (273 mg, 3.25 mmol) for 24 h at 80 ꢀC, the corresponding
amine 4k was obtained as a yellow oil (75 mg, 62%) after purifi-
cation by flash column chromatography on silica (eluent: pentane/
AcOEt [95:5] to [90:10]). 1H NMR (500 MHz, CDCl3)
d: 7.29 (2H, d,
502, 479 cmꢁ1.1H NMR (500 MHz, CDCl3)
d
: 7.27 (2H, d, J ¼ 7.5 Hz),
J ¼ 7.6 Hz), 7.24 (2H, t, J ¼ 7.4 Hz), 7.17e7.13 (2H, m), 6.88 (1H, s),
7.22 (2H, t, J ¼ 7.4 Hz), 7.16e7.13 (2H, m), 6.85e6.84 (1H, m), 6.83
6.87 (1H, d, J ¼ 8.2 Hz), 6.71 (1H, d, J ¼ 8.2 Hz), 3.73 (3H, s), 3.44 (2H,
(1H, s), 3.66 (2H, s), 3.44 (2H, s), 2.15 (3H, s) ppm. 13C NMR
s), 3.42 (2H, s), 2.11 (3H, s) ppm. 13C NMR (125 MHz, CDCl3)
d: 159.7,
(125 MHz, CDCl3) d: 142.9, 139.0, 128.9, 128.3, 127.0, 126.4, 126.7,
141.1, 139.4, 129.2, 128.9, 128.3, 126.9, 121.3, 114.4, 112.5, 61.9, 61.9,
55.2, 42.4 ppm.
124.9, 61.1, 56.1, 42.2 ppm. HRMS: MHþ, found: 218.1009. C13H16NS
requires 218.1003.
4.39. 1-(benzo[d][1,3]dioxol-5-yl)-N-benzyl-N-
methylmethanamine (4l) [38]
4.43. N-benzyl-4-methoxyaniline (4p) [43]
Following the general procedure B, starting from piperonal
Following the general procedure B, starting from benzaldehyde
(75 mg, 0.5 mmol), N-methylbenzylamine (150
mL, 1 mmol), Fe
(51 mL, 0.5 mmol), p-anisidine (123 mg, 1 mmol), Fe (5 mg,
(5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium
formate (273 mg, 3.25 mmol) for 24 h at 80 ꢀC, the corresponding
amine 4l was obtained as a yellow oil (55 mg, 44%) after purification
by flash column chromatography on silica (eluent: pentane/AcOEt
0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium formate
(273 mg, 3.25 mmol) for 48 h at 80 ꢀC, the corresponding amine 4p
was obtained as a yellow powder (99 mg, 93%) after purification by
flash column chromatography on silica (eluent: pentane/AcOEt
[95:5] to [90:10]). 1H NMR (500 MHz, CDCl3)
d: 7.36e7.31 (4H, m),
[95:5] to [90:10]). 1H NMR (500 MHz, CDCl3)
d: 7.37 (2H, t,
7.26e7.23 (1H, m), 6.91 (1H, s), 6.77 (2H, q, J ¼ 7.9 Hz), 5.9 (2H, s),
J ¼ 7.2 Hz), 7.34 (2H, t, J ¼ 7.2 Hz), 7.27 (1H, t, J ¼ 7.2 Hz), 6.78 (2H, d,
3.51 (2H, s), 3.43 (2H, s), 2.17 (2H, s) ppm. 13C NMR (125 MHz,
J ¼ 8.6 Hz), 6.62 (2H, d, J ¼ 8.6 Hz), 4.29 (2H, s), 3.75 (3H, s) (NH
CDCl3)
d
: 147.7, 146.5, 139.4, 133.4, 128.9, 128.3, 126.9, 121.9, 109.3,
signal not observed) ppm. 13C NMR (125 MHz, CDCl3)
d: 152.3,
107.9, 100.9, 61.8, 61.6, 42.1 ppm.
142.5, 139.7, 128.6, 127.6, 127.2, 114.9, 114.2, 55.9, 49.3 ppm.
9

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
4.44. 4-Methoxy-N-(4-methoxybenzyl)aniline (4q) [43]
1 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and
potassium formate (273 mg, 3.25 mmol) for 48 h at 80 ꢀC, the
corresponding amine 4u was obtained as a yellow powder (114 mg,
99%) after purification by flash column chromatography on silica
(eluent: pentane/AcOEt [95:5] to [90:10]). 1H NMR (500 MHz,
Following the general procedure B, starting from p-anisaldehyde
(61
mL, 0.5 mmol), p-anisidine (123 mg, 1 mmol), Fe (5 mg,
0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium formate
(273 mg, 3.25 mmol) for 24 h at 80 ꢀC, the corresponding amine 4q
was obtained as a white powder (90 mg, 74%) after purification by
flash column chromatography on silica (eluent: pentane/AcOEt
CDCl3)
J ¼ 8.4 Hz), 6.60 (2H, d, J ¼ 8.2 Hz), 4.26 (2H, s), 3.75 (3H, s) (NH
signal not observed) ppm. 13C NMR (125 MHz, CDCl3)
: 163.0, 161.1,
152.4, 142.3, 135.4, 135.4, 129.1, 129.0, 115.5, 115.3, 114.9, 114.2, 55.8,
48.6 ppm. 19F NMR (500 MHz, CDCl3)
: 115.71 ppm.
d: 7.34 (2H, t, J ¼ 4.1 Hz), 7.03 (2H, t, J ¼ 8.4 Hz), 6.79 (2H, d,
d
[95:5] to [90:10]). 1H NMR (500 MHz, CDCl3)
d: 7.29 (2H, d,
J ¼ 8.4 Hz), 6.88 (2H, d, J ¼ 8.4 Hz), 6.78 (2H, d, J ¼ 8.7 Hz), 6.62 (2H,
d
d, J ¼ 8.7 Hz), 4.21 (2H, s), 3.80 (3H, s), 3.74 (3H, s) (NH signal not
observed) ppm. 13C NMR (125 MHz, CDCl3)
d: 158.9, 152.3, 131.6,
4.49. 1-(4-((benzyl(methyl)amino)methyl)phenyl)ethan-1-one (4v)
128.9, 122.1, 114.9, 114.3, 114.0, 55.9, 55.3, 48.8 ppm.
4.45. 4-Methoxy-N-(3-methoxybenzyl)aniline (4r)[43]
Following the general procedure B, starting from m-anisalde-
[25]
Following the general procedure B, starting from 4-
acetylbenzaldehyde (75 mg, 0.5 mmol), N-benzylmethylamine
(80 mL, 1 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol)
hyde (61
mL, 0.5 mmol), p-anisidine (123 mg, 1 mmol), Fe (5 mg,
and potassium formate (273 mg, 3.25 mmol) for 24 h at 80 ꢀC, the
corresponding amine 4v was obtained as a colorless oil (101 mg,
80%) after purification by flash column chromatography on silica
0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium formate
(273 mg, 3.25 mmol) for 48 h at 80 ꢀC, the corresponding amine 4r
was obtained as a white powder (119 mg, 98%) after purification by
flash column chromatography on silica (eluent: pentane/AcOEt
(eluent: pentane/Et2O [80:20]). 1H NMR (500 MHz, CDCl3)
d: 7.81
(2H, d, J ¼ 8.7 Hz), 7.35 (2H, d, J ¼ 8.7 Hz), 7.29e7.14 (5H, m), 3.49
[95:5] to [90:10]). 1H NMR (500 MHz, CDCl3)
d
: 7.58 (1H, t,
(2H, s), 3.45 (2H, s), 2.51 (3H, s), 2.08 (3H, s) ppm. 13C NMR
J ¼ 7.8 Hz), 7.28 (1H, d, J ¼ 7.8 Hz), 7.26 (1H, s), 7.13 (1H, d,
J ¼ 8.7 Hz), 7.10 (2H, d, J ¼ 8.7 Hz), 6.93 (2H, d, J ¼ 8.7 Hz), 4.58 (2H,
s), 4.12 (3H, s), 4.06 (3H, s) (NH signal not observed) ppm. 13C NMR
(125 MHz, CDCl3) d: 197.9, 145.3, 139.0, 136.1, 128.9, 128.8, 128.4,
128.3, 127.2, 62.1, 61.4, 42.4, 26.7 ppm.
(125 MHz, CDCl3)
d: 159.9, 152.2, 142.4, 141.4, 129.6, 119.8, 114.9,
4.50. (S)-1-(4-((2-(hydroxymethyl)pyrrolidin-1-yl)methyl)phenyl)
114.1, 113.0, 112.6, 55.8, 55.2, 49.2 ppm.
ethan-1-one (4w) [25]
4.46. N-(benzo[d][1,3]dioxol-5-ylmethyl)-4-methoxyaniline (4s)
Following the general procedure B, starting from 4-
acetylbenzaldehyde (75 mg, 0.5 mmol), L-prolinol (100
mL,
Following the general procedure B, starting from piperonal
(75 mg, 0.5 mmol), p-anisidine (123 mg, 1 mmol), Fe (5 mg,
0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium formate
(273 mg, 3.25 mmol) for 24 h at 80 ꢀC, the corresponding amine 4s
was obtained as a white powder (75 mg, 58%) after purification by
flash column chromatography on silica (eluent: pentane/AcOEt
[95:5] to [90:10]); hmax (liquid film) 3385, 2923, 2853, 1732, 1625,
1511, 1460, 1440, 1405, 1373, 1291, 1233, 1180, 1119, 1097, 1079, 1032,
925, 879, 815, 783, 746, 612, 571, 510 cmꢁ1.1H NMR (500 MHz,
1 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and
potassium formate (273 mg, 3.25 mmol) for 24 h at 80 ꢀC, the
corresponding amine 4w was obtained as a colorless oil (60 mg,
51%) after purification by flash column chromatography on silica
(eluent: CH2Cl2/MeOH [98:2]). 1H NMR (500 MHz, CDCl3)
d: 7.92
(2H, d, J ¼ 8.0 Hz), 7.41 (2H, d, J ¼ 8.0 Hz), 4.08 (1H, d, J ¼ 13.8 Hz),
3.66 (1H, dd, J ¼ 10.5; 3.1 Hz), 3.44 (2H, t, J ¼ 13.2 Hz), 2.99e2.94
(1H, m), 2.79e2.73 (1H, m), 2.69e2.61 (1H, m), 2.60 (3H, s), 2.28
(1H, q, J ¼ 8.0 Hz), 1.99e1.90 (1H, m), 1.89e1.81 (1H, m), 1.77e1.67
CDCl3)
6.60 (2H, d, J ¼ 8.8 Hz), 5.94 (2H, s), 4.19 (2H, s), 3.74 (3H, s) (NH
signal not observed) ppm. 13C NMR (125 MHz, CDCl3)
: 152.3,147.9,
d: 6.87 (1H, s), 6.83 (1H, d, J ¼ 8.2 Hz), 6.79e6.76 (3H, m),
(2H, m) ppm. 13C NMR (125 MHz, CDCl3)
d: 197.8, 145.1, 136.1, 128.7,
128.5, 64.5, 61.8, 58.3, 54.6, 27.6, 26.6, 23.5 ppm.
d
146.7, 142.4, 133.7, 120.6, 114.9, 114.2, 108.3, 108.1, 101.0, 55.9,
49.1 ppm. HRMS: MHþ, found: 257.1051. C15H16NO3 requires
257.1052.
4.51. 1-(4-((4-benzylpiperazin-1-yl)methyl)phenyl)ethan-1-one
(4x)
Following the general procedure B, starting from 4-
4.47. N-(4-chlorobenzyl)-4-methoxyaniline (4t)[43]
acetylbenzaldehyde (75 mg, 0.5 mmol), benzylpiperazine (210 mL,
1 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and
potassium formate (273 mg, 3.25 mmol) for 24 h at 80 ꢀC, the
corresponding amine 4x was obtained as a yellow solid (75 mg,
48%) after purification by flash column chromatography on silica
Following the general procedure B, starting from 4-
chlorobenzaldehyde (70 mg, 0.5 mmol), p-anisidine (123 mg,
1 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and
potassium formate (273 mg, 3.25 mmol) for 48 h at 80 ꢀC, the
corresponding amine 4t was obtained as a white solid (64 mg, 52%)
after purification by flash column chromatography on silica (eluent:
(eluent: CH2Cl2/MeOH [98:2]). 1H NMR (500 MHz, CDCl3)
d: 7.90
(2H, d, J ¼ 8.3 Hz), 7.42 (2H, d, J ¼ 8.2 Hz), 7.31e7.28 (5H, m), 3.55
(2H, s), 3.52 (2H, s), 2.58 (3H, s), 2.56e2.41 (8H, br. s) ppm. 13C NMR
pentane/AcOEt [95:5] to [90:10]). 1H NMR (500 MHz, CDCl3)
d
: 7.31
(125 MHz, CDCl3)
126.7, 63.1, 62.6, 53.2, 53.0, 26.7 ppm. HRMS: MHþ, found: 309.1971.
20H25N2O requires 309.1967.
d: 197.9, 136.1, 129.26, 129.2, 128.4, 128.2, 127.1,
(4H, s), 6.79 (2H, d, J ¼ 8.7 Hz), 6.59 (2H, d, J ¼ 8.7 Hz), 4.27 (2H, s),
3.75 (3H, s) (NH signal not observed) ppm. 13C NMR (125 MHz,
C
CDCl3) d: 152.4, 142.1, 138.3, 132.8, 128.8, 128.8, 114.9, 114.2, 55.8,
48.6 ppm.
4.52. 1-(4-(((2,2-dimethoxyethyl) (methyl)amino)methyl)phenyl)
ethan-1-one (4y) [25]
4.48. N-(4-fluorobenzyl)-4-methoxyaniline (4u)[43]
Following the general procedure B, starting from 4-
Following the general procedure B, starting from 4-
acetylbenzaldehyde mmol),
(75
mg,
0.5
N-methyl-
fluorobenzaldehyde (54
mL, 0.5 mmol), p-anisidine (123 mg,
aminoacetaldehyde dimethyl acetal (99 mL, 1 mmol), Fe (5 mg,
10

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium formate
(273 mg, 3.25 mmol) for 24 h at 80 ꢀC, the corresponding amine 4y
was obtained as a light yellow oil (85 mg, 68%) after purification by
flash column chromatography on silica (eluent: pentane/Et2O
(5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium
formate (273 mg, 3.25 mmol) for 24 h at 80 ꢀC, the corresponding
amine 2ac was obtained as a colorless oil (40 mg, 35%) after puri-
fication by flash column chromatography on silica (eluent: CH2Cl2/
[50:50])). 1H NMR (500 MHz, CDCl3)
d
: 7.91 (2H, d, J ¼ 8.3 Hz), 7.42
MeOH [90:10] to [70:30]). 1H NMR (500 MHz, CDCl3)
d: 4.80 (1H, s),
(2H, d, J ¼ 8.3 Hz), 4.51 (1H, t, J ¼ 5.0 Hz), 3.61 (2H, s), 3.32 (6H, s),
4.70 (1H, s), 3.70 (2H, t, J ¼ 5.0 Hz), 2.67e2.64 (3H, m), 2.55e2.52
2.58 (3H, s), 2.54 (2H, d, J ¼ 5.0 Hz), 2.28 (3H, s). 13C NMR (125 MHz,
(2H, m), 2.42 (3H, s), 2.36 (2H, t, J ¼ 7.0 Hz), 2.11 (3H, s), 2.10e2.06
CDCl3)
d
: 197.9, 136.0, 128.9, 128.5, 126.5, 102.8, 62.4, 58.5, 53.3,
(1H, m), 1.72e1.62 (3H, m), 1.59 (3H, s), 1.57e1.51 (1H, m) ppm. 13
C
43.2, 26.6 ppm.
NMR (125 MHz, CDCl3) d: 208.9, 145.6, 113.5, 59.4, 57.8, 55.9, 44.6,
41.6, 41.2, 30.1, 29.6, 26.7, 17.5 ppm.
4.53. 6-((2,2-dimethoxyethyl) (methyl)amino)-1-phenylhexan-1-
one (4z) [25]
4.57. (R)-5-(2-((2,2-dimethoxyethyl) (methyl)amino)ethyl)-6-
methylhept-6-en-2-one (4ad) [25]
Following the general procedure B, starting from ketoaldehyde
1z (95 mg, 0.5 mmol), N-methylaminoacetaldehyde dimethyl acetal
(99 mL, 1 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol)
Following the general procedure B, starting from ketoaldehyde
1aa (84 mg, 0.5 mmol), N-methylaminoacetaldehyde dimethyl
and potassium formate (273 mg, 3.25 mmol) for 24 h at 80 ꢀC, the
corresponding amine 4z was obtained as a colorless oil (89 mg,
61%) after purification by flash column chromatography on silica
acetal (99
mL, 1 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (273 mg, 3.25 mmol) for 24 h
at 80 ꢀC, the corresponding amine 4ad was obtained as a colorless
oil (71 mg, 52%) after purification by flash column chromatography
on silica (eluent: CH2Cl2/MeOH [98:2]). 1H NMR (500 MHz, CDCl3)
(eluent: CH2Cl2/MeOH [90:10]). 1H NMR (500 MHz, CDCl3)
d: 7.93
(2H, d, J ¼ 7.9 Hz), 7.53 (1H, t, J ¼ 7.6 Hz), 7.44 (2H, t, J ¼ 7.6 Hz), 4.46
(1H, t, J ¼ 5.1 Hz), 3.34 (6H, s), 2.95 (2H, t, J ¼ 7.3 Hz), 2.49 (2H, d,
J ¼ 5.1 Hz), 2.39 (2H, t, J ¼ 7.2 Hz), 2.27 (3H, s), 1.74 (2H, quint,
J ¼ 7.5 Hz), 1.51 (2H, quint, J ¼ 7.5 Hz), 1.37 (2H, quint, J ¼ 7.7 Hz)
d
: 4.76 (s, 1H), 4.67 (s, 1H), 4.47 (1H, t, J ¼ 5.0 Hz), 3.35 (6H, s), 2.49
(2H, d, J ¼ 5.0 Hz), 2.33 (4H, q, J ¼ 7.3 Hz), 2.28 (3H, s), 2.10 (3H, s),
2.05e1.98 (1H, m), 1.70e1.61 (1H, m), 1.56 (3H, s), 1.55e1.47 (3H, m)
ppm. 13C NMR (125 MHz, CDCl3)
d: 200.3, 136.9, 132.8, 128.5, 127.9,
ppm. 13C NMR (125 MHz, CDCl3)
d: 208.9, 146.2, 112.7, 102.7, 58.9,
102.7, 58.8, 58.3, 53.2, 43.2, 38.4, 27.1, 26.9, 24.1 ppm.
56.6, 53.3, 44.8, 43.2, 41.5, 30.4, 30.0, 26.9, 17.5 ppm.
4.54. 6-((2-hydroxyethyl) (methyl)amino)-1-phenylhexan-1-one
(4aa) [25]
4.58. (R)-5-(2-((S)-2-(hydroxymethyl)pyrrolidin-1-yl)ethyl)-6-
methylhept-6-en-2-one (4ae) [25]
Following the general procedure B, starting from ketoaldehyde
1z (95 mg, 0.5 mmol), N-methylethanolamine (61 mL, 1 mmol), Fe
(5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium
formate (273 mg, 3.25 mmol) for 24 h at 80 ꢀC, the corresponding
amine 2aa was obtained as a white powder (74 mg, 59%) after
purification by flash column chromatography on silica (eluent:
Following the general procedure B, starting from ketoaldehyde
1aa (84 mg, 0.5 mmol), L-prolinol (100
mL, 1 mmol), Fe (5 mg,
0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium formate
(273 mg, 3.25 mmol) for 24 h at 80 ꢀC, the corresponding amine 4ae
was obtained as a colorless oil (62 mg, 49%) after purification by
flash column chromatography on silica (eluent: CH2Cl2/MeOH
CH2Cl2/MeOH [90:10] to [70:30]). 1H NMR (500 MHz, CDCl3)
d: 7.93
(2H, d, J ¼ 7.8 Hz), 7.54 (1H, t, J ¼ 7.2 Hz), 7.43 (2H, t, J ¼ 7.2 Hz), 3.73
(2H, t, J ¼ 4.2 Hz), 2.97 (2H, t, J ¼ 7.0 Hz), 2.78 (2H, t, J ¼ 5.0 Hz), 2.68
(2H, t, J ¼ 7.6 Hz), 2.47 (3H, s), 1.75 (2H, quint, J ¼ 7.2 Hz), 1.66 (2H,
quint, J ¼ 6.7 Hz), 1.41 (2H, quint, J ¼ 7.0 Hz) ppm. 13C NMR
[99:1]). 1H NMR (500 MHz, CDCl3)
d: 4.79 (1H, s), 4.70 (1H, d,
J ¼ 1.6 Hz), 3.59 (1H, dd, J ¼ 2.9, 10.6 Hz), 3.36 (1H, d, J ¼ 10.6),
3.21e3.15 (1H, br. s), 2.68e2.63 (1H, m), 2.60e2.55 (1H, m), 2.35
(2H, t, J ¼ 7.5 Hz), 2.21e2.12 (2H, m), 2.11 (3H, s), 1.89e1.81 (1H, m),
(125 MHz, CDCl3) d: 199.1, 135.9, 132.0, 127.6, 127.0, 58.1, 56.5, 56.4,
40.4, 37.2, 25.6, 24.7, 22.7 ppm.
1.80e1.71 (4H, m), 1.68e1.61 (2H, m), 1.59e1.51 (6H, m) ppm. 13
C
NMR (125 MHz, CDCl3)
44.8, 41.5, 32.80, 30.1, 27.5, 27.1, 23.6, 17.2 ppm.
d: 209.0, 146.1, 113.2, 65.1, 61.8, 54.1, 52.5,
4.55. 6-(benzyl(methyl)amino)-1-phenylhexan-1-one (4 ab) [25]
Following the general procedure B, starting from ketoaldehyde
General procedure C for the synthesis of chalcone indanone
derivatives. In a 50 mL round-bottom flask was charged the
indanone (1.322 g, 5 mmol, 1 equiv.), the appropriate aldehyde
(5 mmol, 1 equiv.) and methanol (25 mL). Then KOH (0.140 mg,
2.5 mmol, 0.25 equiv.) was added and the reaction mixture was
stirred during 2 h at room-temperature. Then the precipitate was
filtered and washed with cold methanol to afford the pure product.
Data of the enones are in agreement with the literature.
1z (95 mg, 0.5 mmol), N-benzylmethylamine (80 mL, 1 mmol), Fe
(5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and potassium
formate (273 mg, 3.25 mmol) for 24 h at 80 ꢀC, the corresponding
amine 2 ab was obtained as a light yellow (115 mg, 78%) after pu-
rification by flash column chromatography on silica (eluent:
CH2Cl2/MeOH [90:10]). 1H NMR (500 MHz, CDCl3)
d: 7.90 (2H, d,
J ¼ 7.9 Hz), 7.49 (1H, t, J ¼ 7.2 Hz), 7.40 (2H, t, J ¼ 7.9 Hz), 7.29e7.23
(4H, m), 7.21e7.16 (1H, m), 3.46 (2H, s), 2.91 (2H, t, J ¼ 7.3 Hz), 2.36
(2H, t, J ¼ 7.3 Hz), 2.16 (3H, s), 1.70 (2H, quint, J ¼ 7.6 Hz), 1.54 (2H,
quint, J ¼ 7.3 Hz), 1.36 (2H, quint, J ¼ 7.6 Hz) ppm. 13C NMR
4.59. (E)-2-Benzylidene-2,3-dihydro-1H-inden-1-one (5l) [45]
(125 MHz, CDCl3) d: 200.3, 138.6, 137.0, 129.1, 128.5, 128.2 (2C),
127.9, 126.9, 62.2, 57.1, 42.0, 38.4, 27.1, 24.1 ppm.
Following the general procedure C starting from benzaldehyde
(508
66%). 1H NMR (500 MHz, CDCl3)
(3H, m), 7.63e7.61 (1H, m), 7.57e7.55 (1H, m), 7.48e7.39 (4H, m),
4.06 (2H, s) ppm. 13C NMR (125 MHz, CDCl3)
: 194.4, 149.7, 138.0,
m
L, 5 mmol), enone 5l was obtained as a white solid (1.46 g,
4.56. (R)-5-(2-((2-hydroxyethyl) (methyl)amino)ethyl)-6-
methylhept-6-en-2-one (4ac) [25]
d: 7.92 (1H, d, J ¼ 7.6 Hz), 7.69e7.68
d
Following the general procedure B, starting from ketoaldehyde
1aa (84 mg, 0.5 mmol), N-methylethanolamine (61 mL, 1 mmol), Fe
135.4, 134.7, 134.7, 134.0, 130.8 (2C), 129.7, 129.0 (2C), 127.7, 126.2,
124.5, 32.5 ppm.
11

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
4.60. (E)-2-(4-methoxybenzylidene)-2,3-dihydro-1H-inden-1-one
126.6, 126.2, 124.3, 32.3 ppm.
(5m) [46]
4.66. (E)-2-((1H-pyrrol-2-yl)methylene)-2,3-dihydro-1H-inden-1-
Following the general procedure
methoxybenzaldehyde (608 L, 5 mmol), enone 5m was obtained
as a white solid (2.25 g, 90%). 1H NMR (500 MHz, CDCl3)
: 7.90 (1H,
C
starting from 4-
one (5s) [48]
m
d
Following the general procedure C starting from pyrrole-2-
d, J ¼ 7.6 Hz), 7.65e7.63 (3H, m), 7.61e7.59 (1H, m), 7.56e7.54 (1H,
carboxaldehyde (476 mg, 5 mmol), enone 5s was obtained as a
m), 7.43e7.41 (1H, m), 6.99e6.97 (2H, m), 4.01 (2H, s), 3.86 (3H, s)
yellow solid (1.77 g, 80%). 1H NMR (500 MHz, CDCl3)
d: 9.17e8.98
ppm. 13C NMR (125 MHz, CDCl3)
d: 194.4, 160.9, 149.5, 138.3, 134.4,
(1H, br. s), 7.89 (1H, d, J ¼ 7.6 Hz), 7.67 (1H, br. s), 7.62e7.59 (1H, m),
7.56e7.55 (1H, m), 7.44e7.41 (1H, m), 7.09e7.08 (1H, m), 6.76 (1H,
br. s), 6.44e6.42 (1H, m), 3.90 (2H, s) ppm. 13C NMR (125 MHz,
133.8, 132.6 (2C), 132.4, 128.2, 127.2, 126.1, 124.3, 114.5 (2C), 55.4,
32.5 ppm.
CDCl3) d: 194.1, 148.9, 134.2, 129.4, 129.3, 127.6, 126.1, 124.1, 123.7,
4.61. 2-[Benzo{1,3}dioxol-5-yl-methylene]-indan-1-one (5n) [46]
122.9, 114.9, 112.0, 32.4 ppm.
Following the general procedure C starting from piperonal
4.67. 1,3-Diphenyl-1-propanone (6a) [19d]
(751 mg, 5 mmol), enone 5n was obtained as a white solid (2.40 g,
91%). 1H NMR (500 MHz, CDCl3)
d
: 7.90 (1H, d, J ¼ 7.6 Hz), 7.62e7.55
(3H, m), 7.42 (1H, t, J ¼ 7.4 Hz), 7.21e7.19 (2H, m), 6.04 (2H, s), 4.00
(2H, s) ppm. 13C NMR (125 MHz, CDCl3)
: 194.3, 149.4, 149.1, 148.3,
Following the general procedure A, starting from chalcone
(107 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6a was obtained as a white
powder (99 mg, 94%) after purification by flash column chroma-
tography on silica (eluent: pentane/AcOEt [95:5]). 1H NMR
d
138.2, 134.5, 133.9, 132.8, 129.8, 127.7, 127.0, 126.1, 124.4, 109.5,
108.9, 101.7, 32.5 ppm.
4.62. (E)-2-(4-(trifluoromethyl)benzylidene)-2,3-dihydro-1H-
inden-1-one (5o) [45]
(500 MHz, CDCl3)
d
: 7.95 (2H, d, J ¼ 7.8 Hz), 7.56 (1H, t, J ¼ 7.4 Hz),
7.46 (2H, t, J ¼ 7.7 Hz), 7.30 (2H, t, J ¼ 7.6 Hz), 7.27e7.20 (5H, m), 3.31
(2H, t, J ¼ 7.7 Hz), 3.08 (2H, t, J ¼ 7.7 Hz) ppm. 13C NMR (125 MHz,
Following the general procedure
fluoromethyl)benzaldehyde (683 L, 5 mmol), enone 5o was ob-
tained as a white solid (2.60 g, 90%). 1H NMR (500 MHz, CDCl3)
C
starting from 4-(tri-
CDCl3) d: 199.3, 141.3, 136.9, 133.1, 128.6, 128.5, 128.4, 128.1, 126.2,
m
40.5, 30.2 ppm.
d
:
7.92 (1H, d, J ¼ 7.8 Hz), 7.78e7.77 (2H, m), 7.72e7.71 (2H, m),
4.68. 1-(4-Methoxyphenyl)-3-(3,4,5-trimethoxyphenyl)-1-
propanone (6b) [19d]
7.68e766 (1H, br. s), 7.66e7.64 (1H, m), 7.59e7.57 (1H, m),
7.47e744 (1H, m), 4.07 (2H, s) ppm. 13C NMR (125 MHz, CDCl3)
d:
194.0, 149.5, 138.8, 138.8, 137.7, 136.9, 135.1, 132.0, 130.9 (q,
Following the general procedure A, starting from enone
(164 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6b was obtained as a white
powder (161 mg, 98%) after purification by flash column chroma-
tography on silica (eluent: pentane/AcOEt [95:5]). 1H NMR
J ¼ 32.7 Hz, 1C), 130.6, 127.9, 126.3, 125.8 (q, J ¼ 3.8 Hz, 1C), 124.7,
32.3 ppm. 19F NMR (500 MHz, CDCl3)
d: 62.79 ppm.
4.63. (E)-2-(4-Dimethylaminobenzylidene)-indan-1-one (5p) [46]
Following the general procedure C starting from 4-(dimethyla-
(500 MHz, CDCl3)
d
: 7.93 (2H, d, J ¼ 8.6 Hz), 6.92 (2H, d, J ¼ 8.6 Hz),
mino)benzaldehyde (756 mg, 5 mmol), enone 5p was obtained as a
6.45 (2H, s), 3.85 (3H, s), 3.83 (6H, s), 3.81 (3H, s), 3.23 (2H, t,
yellow solid (1.57 g, 60%). 1H NMR (500 MHz, CDCl3)
d
: 7.89 (1H, d,
J ¼ 7.6 Hz), 2.99 (2H, t, J ¼ 7.6 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d:
J ¼ 7.7 Hz), 7.64 (1H, br. s), 7.60e7.53 (4H, m), 7.42e7.40 (1H, m),
197.8, 163.5, 153.2, 137.3, 136.3, 130.3, 130, 113.8, 105.3, 60.9, 56.1,
55.5, 40.3, 30.8 ppm.
6.76e6.74 (2H, m), 3.98 (2H, s), 3.04 (6H, s) ppm. 13C NMR
(125 MHz, CDCl3) d: 194.4, 151.2, 149.4, 138.8, 135.0, 133.8, 132.8
(2C), 129.9, 127.4, 126.0, 124.1, 123.3, 111.9 (2C), 40.1 (2C), 32.7 ppm.
4.69. 3-(4-fluorophenyl)-1-(4-methoxyphenyl)propan-1-one (6c)
[19d]
4.64. (E)-2-(furan-2-ylmethylene)-2,3-dihydro-1H-inden-1-one
(5q) [47]
Following the general procedure A, starting from enone
(128 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (252 mg, 3 mmol) for 24 h at
45 ꢀC, the corresponding ketone 6c was obtained as a white powder
(109 mg, 85%) after purification by flash column chromatography
on silica (eluent: pentane/AcOEt [95:5]). 1H NMR (500 MHz, CDCl3)
Following the general procedure C starting from furfural (414
5 mmol), enone 5q was obtained as a yellow solid (1.3 g, 62%). 1H
NMR (500 MHz, CDCl3)
mL,
d
: 7.88 (1H, d, J ¼ 7.8 Hz), 7.63e7.59 (2H, m),
7.54 (1H, d, J ¼ 7.8 Hz), 7.46e7.45 (1H, m), 7.41 (1H, t, J ¼ 7.5 Hz),
6.76 (1H, d, J ¼ 3.3 Hz), 6.56e6.52 (1H, m), 4.04 (2H, s) ppm. 13C
d
: 7.93 (2H, d, J ¼ 8.5 Hz), 7.20 (2H, t, J ¼ 6.7 Hz), 6.97 (2H, t,
NMR (125 MHz, CDCl3)
d
: 194.0, 152.3, 149.8, 145.4, 138.5, 134.5,
J ¼ 8.5 Hz), 6.92 (2H, d, J ¼ 8.5 Hz), 3.86 (3H, s), 3.22 (2H, t,
132.6, 127.5, 126.2, 124.2, 120.1, 116.6, 112.7, 32.4 ppm.
J ¼ 7.6 Hz), 3.03 (2H, t, J ¼ 7.5 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d:
197.6, 163.5, 162.4 (d, JC-F ¼ 243.8 Hz), 137.1 (d, JC-F ¼ 3.1 Hz), 130.3,
129.9, 129.8 (d, JC-F ¼ 7.8 Hz), 115.2 (d, JC-F ¼ 21.1 Hz), 113.8, 55.5,
4.65. (E)-2-(thiophen-2-ylmethylene)-2,3-dihydro-1H-inden-1-
one (5r) [47]
40.1, 29.5 ppm. 1H NMR (500 MHz, CDCl3)
d: 117.4 ppm.
Following the general procedure
thiophenecarboxaldehyde (469 L, 5 mmol), enone 5r was ob-
tained as a white solid (1.77 g, 80%). 1H NMR (500 MHz, CDCl3)
C
starting from 2-
4.70. 1-(4-methoxyphenyl)-3-(4-nitrophenyl)propan-1-one (6d)
[44]
m
d
:
7.90e7.89 (2H, m), 7.63e7.56 (3H, m), 7.45e7.41 (2H, m), 7.18 (1H,
Following the general procedure A, starting from enone
(143 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
dd, J ¼ 5.0, 3.7 Hz), 3.93 (2H, s) ppm. 13C NMR (125 MHz, CDCl3)
d:
193.8, 149.0, 139.9, 138.5, 134.6, 133.1, 132.8, 130.55, 128.2, 127.7,
12

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
at 45 ꢀC, the corresponding ketone 6d was obtained as a white
powder (86 mg, 60%) after purification by flash column chroma-
tography on silica (eluent: pentane/AcOEt [90:10]). 1H NMR
(1H, dd, J ¼ 0.8 Hz), 7.31e7.16 (6H, m), 6.52 (1H, dd, J ¼ 1.7 Hz), 3.16
(2H, t, J ¼ 7.7 Hz), 3.05 (2H, t, J ¼ 7.7 Hz) ppm. 13C NMR (125 MHz,
CDCl3) d: 188.5, 152.7, 146.3, 141, 128.5, 128.4, 126.2, 117.1, 112.2,
(500 MHz, CDCl3)
d
: 8.15 (2H, d, J ¼ 8.7 Hz), 7.93 (2H, d, J ¼ 9.0 Hz),
40.2, 30.0 ppm.
7.42 (2H, d, J ¼ 8.7 Hz), 6.93 (2H, d, J ¼ 9.0 Hz), 3.87 (3H, s), 3.30 (2H,
t, J ¼ 7.3 Hz), 3.17 (2H, t, J ¼ 7.3 Hz) ppm. 13C NMR (125 MHz, CDCl3)
4.75. 3-Phenyl-1-(2-thienyl)-2-propanone (6i) [19d]
d
: 196.7, 163.7, 149.4, 146.5, 130.3, 129.6, 129.4, 123.8, 113.9, 55.5,
39.1, 29.9 ppm.
Following the general procedure A, starting from enone
(107 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6i was obtained as a white
powder (84 mg, 78%) after purification by flash column chroma-
tography on silica (eluent: pentane/AcOEt [95:5]). 1H NMR
4.71. 1-(4-bromophenyl)-3-phenylpropan-1-one (6e)
Following the general procedure A, starting from enone
(144 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6e was obtained as a white
powder (92 mg, 64%) after purification by flash column chroma-
tography on silica (eluent: pentane/AcOEt [95:5]); hmax (liquid film)
3025, 2924, 1681, 1603, 1581, 1494, 1452, 1394, 1359, 1329, 1289,
1202,1179,1101,1071,1054,1028,1008, 976, 844, 829, 778, 743, 698,
(500 MHz, CDCl3)
d
: 7.69 (1H, d, J ¼ 3.8 Hz), 7.62 (1H, d, J ¼ 4.9 Hz),
7.32e7.19 (5H, m), 7.11 (1H, t, J ¼ 3.8 Hz), 3.24 (2H, t, J ¼ 7.8 Hz), 3.08
(2H, t, J ¼ 7.8 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d: 192.2, 144.2,
141, 133.6, 131.8, 128.6 (2C), 128.5 (2C), 128.1, 126.3, 41.2, 30.4 ppm.
4.76. 3-Phenyl-1-(1h-pyrrol-2-yl)-2-propanone (6j) [19d]
627, 557, 521 cmꢁ1.1H NMR (500 MHz, CDCl3)
d: 7.71 (2H, d,
J ¼ 8.5 Hz), 7.48 (2H, d, J ¼ 8.5 Hz), 7.20 (2H, t, J ¼ 7.5 Hz), 7.15e7.09
Following the general procedure A, starting from enone (99 mg,
0.5 mmol), F (5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and
potassium formate (210 mg, 2.5 mmol) for 24 h at 45 ꢀC, the cor-
responding ketone 6j was obtained as a white powder (98 mg, 98%)
after purification by flash column chromatography on silica (eluent:
(3H, m), 3.16 (2H, t, J ¼ 7.6 Hz), 2.9 (2H, t, J ¼ 7.6 Hz) ppm. 13C NMR
(125 MHz, CDCl3) d: 198.2, 141.1, 135.6, 132, 129.6, 128.6, 128.5,
128.3, 126.3, 40.5, 30.1. HRMS: MHþ, found: 289.0230. C15H14OBr
requires 289.0228.
pentane/AcOEt [95:5]). 1H NMR (500 MHz, CDCl3)
d: 9.37 (1H, s,
4.72. 1-(4-Bromophenyl)-3-(2-methoxyphenyl)-1-propanone (6f)
[19d]
(NH)), 7.23 (2H, t, J ¼ 7.4 Hz), 7.18e7.11 (4H, m), 6.95 (1H, td, J ¼ 1.6,
1.3 Hz), 6.83e6.81 (1H, m), 6.20e6.19 (1H, m), 3.05e3.02 (2H, m),
2.99e2.95 (2H, m) ppm. 13C NMR (125 MHz, CDCl3)
d: 189.6, 141.3,
Following the general procedure A, starting from enone
(159 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6f was obtained as a white
powder (123 mg, 77%) after purification by flash column chroma-
tography on silica (eluent: pentane/AcOEt [95:5]). 1H NMR
131.8, 128.5, 128.4, 126.2, 124.4, 116, 110.7, 39.6, 30.8 ppm.
4.77. 2-Methyl-1,5-diphenyl-1-pentanone (6k) [19d]
Following the general procedure A, starting from enone
(126 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6k was obtained as a colorless
oil (56 mg, 44%) after purification by flash column chromatography
(500 MHz, CDCl3)
d
: 7.84 (2H, d, J ¼ 8.5 Hz), 7.58 (2H, d, J ¼ 8.5 Hz),
7.24e7.19 (2H, m), 6.92e6.86 (2H, m), 3.83 (3H, s), 3.23 (2H, t,
J ¼ 7.7 Hz), 3.04 (2H, t, J ¼ 7.7 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d:
198.9, 157.5, 135.7, 131.9, 130.2, 129.7, 129.3, 128.1, 127.7, 120.6, 110.3,
55.2, 38.9, 25.8 ppm.
on silica (eluent: pentane/Et2O [95:5]). 1H NMR (500 MHz, CDCl3)
d:
7.93 (2H, d, J ¼ 7.5 Hz), 7.55 (1H, t, J ¼ 7.3 Hz), 7.46 (2H, t, J ¼ 7.7 Hz),
7.27e7.24 (2H, m), 7.18e7.14 (3H, m), 3.48 (1H, sext., J ¼ 6.8 Hz),
2.61 (2H, ABX2, JAB ¼ 12.7 Hz, JAX ¼ 6.0 Hz, JBX ¼ 6.0 Hz), 1.92e1.84
(1H, m), 1.65 (2H, qt, J ¼ 7.8 Hz), 1.54e1.48 (1H, m), 1.20 (3H, d,
4.73. 1,3-bis(4-bromophenyl)propan-1-one (6g)
Following the general procedure A, starting from enone
(183 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6g was obtained as a white
powder (145 mg, 79%) after purification by flash column chroma-
tography on silica (eluent: pentane/AcOEt [95:5]); hmax (liquid film)
2922, 1740, 1682, 1584, 1486, 1447, 1396, 1360, 1290, 1267, 1199,
1178,1102,1068,1008, 977, 840, 807, 771, 711, 689, 565, 523 cmꢁ1.1H
J ¼ 6.8 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d: 204.4, 142.2, 136.7,
132.9, 128.7, 128.4, 128.3, 128.2, 126.8, 40.5, 36.0, 33.3, 29.2,
17.4 ppm.
4.78. 2-Benzyl-2,3-dihydro-1H-inden-1-one (6l)
Following the general procedure A, starting from enone 5l
(110 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6l was obtained as a colorless oil
(99 mg, 89%) after purification by flash column chromatography on
silica (eluent: pentane/AcOEt [90:10]); hmax (liquid film) 3027,
2920, 2852, 1705, 1603, 1496, 1464, 1453, 1432, 1327, 1289, 1274,
1207, 1181, 1150, 1092, 1092, 1030, 1001, 953, 897, 879, 822, 777, 741,
NMR (500 MHz, CDCl3)
d
: 7.79 (2H, d, J ¼ 8.1 Hz), 7.59 (2H, d,
J ¼ 8.4 Hz), 7.40 (2H, d, J ¼ 8.1 Hz), 7.11 (2H, d, J ¼ 7.8 Hz), 3.23 (2H, t,
J ¼ 7.6 Hz), 3.01 (2H, t, J ¼ 7.4 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d:
197.8,140,135.4,132,131.6,130.3,129.6,128.4,120.0, 40.1, 29.3 ppm.
HRMS: MHþ, found: 366.9334. C15H13OBr2 requires 366.9333.
4.74. 1-(2-Furanyl)-3-phenyl-2-propanone (6h) [19d]
699, 628, 608, 587, 545 cmꢁ1.1H NMR (500 MHz, CDCl3)
d: 7.79 (1H,
d, J ¼ 7.5 Hz), 7.57 (1H, td, J ¼ 7.5,1.1 Hz), 7.40 (1H, dt, J ¼ 7.6, 0.8 Hz),
7.37 (1H, td, J ¼ 7.8, 0.7 Hz), 7.32e7.29 (2H, m), 7.26e7.21 (3H, m),
3.41 (1H, ABX, JAB ¼ 14.0 Hz, JAX ¼ 4.3 Hz), 3.17 (1H, ABX,
JAB ¼ 17.2 Hz, JAX ¼ 7.9 Hz), 3.01 (1H, ddt, J ¼ 10.4, 7.9, 4.0 Hz), 2.86
(1H, ABX, JAB ¼ 17.1 Hz, JAX ¼ 4.0 Hz), 2.67 (1H, ABX, JAB ¼ 13.9 Hz,
Following the general procedure A, starting from enone (99 mg,
0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg, 0.0126 mmol) and
potassium formate (210 mg, 2.5 mmol) for 24 h at 45 ꢀC, the cor-
responding ketone 6h was obtained as a white powder (80 mg,
80%) after purification by flash column chromatography on silica
JAX ¼ 10.4 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d: 207.9, 153.7, 139.7,
(eluent: pentane/AcOEt [95:5]). 1H NMR (500 MHz, CDCl3)
d
: 7.57
136.6, 134.9, 128.9, 128.6, 127.5, 126.6, 126.4, 124.1, 49.0, 37.0,
13

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
32.2 ppm. HRMS: MHþ, found: 223.1123. C16H15
223.1123.
O
requires
207.2, 153.3, 143.8, 136.4, 135, 129.3, 127.6, 126.6, 126.5 (1C, q, JC-
¼ 3.7 Hz), 123.2, 48.6, 36.7, 32.1 ppm. 19F NMR (500 MHz, CDCl3)
d:
F
62.37 ppm. HRMS: MHþ, found: 291.1005. C17H14OF3 requires
291.0997.
4.79. 2-(4-methoxybenzyl)-2,3-dihydro-1H-inden-1-one (6m)
Following the general procedure A, starting from enone 5m
(126 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6m was obtained as a colorless
oil (123 mg, 97%) after purification by flash column chromatog-
raphy on silica (eluent: pentane/AcOEt [90:10]); hmax (liquid film)
3030, 2931, 2835, 1705, 1609, 1585, 1511, 1463, 1433, 1324, 1294,
1272, 1244, 1207, 1177, 1151, 1108, 1092, 1032, 1002, 811, 796, 758,
4.82. 2-(4-(dimethylamino)benzyl)-2,3-dihydro-1H-inden-1-one
(6p)
Following the general procedure A, starting from enone 5p
(131 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6p was obtained as a yellow oil
(44 mg, 33%) after purification by flash column chromatography on
silica (eluent: pentane/AcOEt [90:10]); hmax (liquid film) 2916,
2849, 2800, 1705, 1676, 1610, 1519, 1463, 1444, 1433, 1340, 1293,
1273, 1207, 1164, 1151, 1115, 1093, 1060, 1042, 1001, 980, 946, 897,
824, 804, 786, 754, 727, 673, 625, 601, 555, 513 cmꢁ1.1H NMR
729, 679, 621, 602, 589, 572, 564 cmꢁ1.1H NMR (500 MHz, CDCl3)
d:
7.77 (1H, d, J ¼ 7.4 Hz), 7.57 (1H, td, J ¼ 7.0, 0.9 Hz), 7.40 (1H, d,
J ¼ 7.7 Hz), 7.36 (1H, t, J ¼ 7.4 Hz), 7.16 (2H, d, J ¼ 8.4 Hz), 6.83 (2H, d,
J ¼ 8.7 Hz), 3.79 (3H, s), 3.31 (1H, ABX, JAB ¼ 14.1 Hz, JAX ¼ 4.3 Hz),
3.16 (1H, ABX, JAB ¼ 17.2 Hz, JAX ¼ 7.8 Hz), 2.97 (1H, ABX, JAB ¼ 8 Hz,
JAX ¼ 4 Hz), 2.85 (1H, ABX, JAB ¼ 17.2 Hz, JAX ¼ 3.9 Hz), 2.65 (1H, ABX,
(500 MHz, CDCl3)
d
: 7.77 (1H, d, J ¼ 7.7 Hz), 7.56 (1H, td, J ¼ 7.4,
0.9 Hz), 7.40 (1H, d, J ¼ 7.7 Hz), 7.36 (1H, t, J ¼ 7.4 Hz), 7.12 (2H, d,
J ¼ 8.5 Hz), 6.70 (2H, d, J ¼ 8.2 Hz), 3.30 (1H, ABX, JAB ¼ 14.0 Hz,
JAX ¼ 4.3 Hz), 3.16 (1H, ABX, JAB ¼ 17.2 Hz, JAX ¼ 7.7 Hz), 2.96e2.90
(1H, m), 2.92 (6H, s), 2.88 (1H, ABX, JAB ¼ 17.2 Hz, JAX ¼ 3.9 Hz), 2.59
(1H, ABX, JAB ¼ 14.0 Hz, JAX ¼ 10.4 Hz) ppm. 13C NMR (125 MHz,
JAB ¼ 14 Hz, JAX ¼ 10.2 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d: 208.1,
158.2, 153.7, 136.6, 134.8, 131.6, 129.9, 127.4, 126.6, 124.2, 113.9, 55.3,
49.2, 36.1, 32.1 ppm. HRMS: MHþ, found: 253.1232. C17H17O2 re-
quires 253.1229.
CDCl3) d: 208.3, 153.9, 136.7, 134.7, 129.6, 127.4, 126.6, 124.0, 112.9,
4.80. 2-(benzo[d][1,3]dioxol-5-ylmethyl)-2,3-dihydro-1H-inden-1-
one (6n)
49.3, 40.8, 36.1, 32.2 ppm. HRMS: MHþ, found: 266.1543. C18H20NO
requires 266.1545.
Following the general procedure A, starting from enone 5n
(132 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6n was obtained as a white
powder (111 mg, 83%) after purification by flash column chroma-
tography on silica (eluent: Pentane/AcOEt [90:10]); hmax (liquid
film) 3073, 2904, 2783, 1702, 1608, 1587, 1502, 1489, 1465, 1441,
1364, 1330, 1296, 1281, 1247, 1232, 1208, 1188, 1153, 1118, 1098,
1035, 1003, 959, 928, 898, 879, 843, 807, 789, 765, 748, 721, 685,
4.83. 2-(Furan-2-ylmethyl)-2,3-dihydro-1H-inden-1-one (6q)
Following the general procedure A, starting from enone 5q
(105 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6q was obtained as a yellow oil
(80 mg, 71%) after purification by flash column chromatography on
silica (eluent: pentane/AcOEt [90:10]); hmax (liquid film) 2918,
2848, 1706, 1607, 1506, 1464, 1431, 1382, 1328, 1293, 1277, 1207,
1181, 1148, 1093, 1075, 1042, 1010, 953, 929, 884, 798, 757, 724, 670,
641, 602, 585, 573, 549, 521 cmꢁ1.1H NMR (500 MHz, CDCl3)
d: 7.77
(1H, d, J ¼ 7.7 Hz), 7.57 (1H, td, J ¼ 7.4, 0.9 Hz), 7.41 (1H, d,
J ¼ 7.7 Hz), 7.37 (1H, t, J ¼ 7.4 Hz), 6.74 (1H, d, J ¼ 1.6 Hz), 6.73 (1H,
s), 6.68 (1H, dd, J ¼ 6.5,1.4 Hz), 5.93 (2H, s), 3.29 (1H, ABX, JAB ¼ 14.1,
4.4 Hz), 3.17 (1H, ABX, JAB ¼ 17.1 Hz, JAX ¼ 7.8 Hz), 2.94 (1H, ABX,
JAB ¼ 7.7 Hz, JAX ¼ 4.0 Hz), 2.86 (1H, ABX, JAB ¼ 17.1, JAX ¼ 4.1 Hz),
2.62 (1H, ABX, JAB ¼ 14.1 Hz, JAX ¼ 10.2 Hz) ppm. 13C NMR (125 MHz,
651, 599, 584, 552 cmꢁ1.1H NMR (500 MHz, CDCl3)
d: 7.78 (1H, d,
J ¼ 8.11 Hz), 7.58 (1H, td, J ¼ 7.5, 1.1 Hz), 7.43 (1H, dt, J ¼ 7.6, 0.8 Hz),
7.37 (1H, td, J ¼ 7.0, 0.8 Hz), 7.29 (1H, q, J ¼ 0.8 Hz), 6.27 (1H, q,
J ¼ 1.9 Hz), 6.06 (1H, q, J ¼ 0.9 Hz), 3.32 (1H, ABX, JAB ¼ 14.7 Hz,
JAX ¼ 4.5 Hz), 3.31 (1H, ABX, JAB ¼ 17.3 Hz, JAX ¼ 7.8 Hz), 3.05e2.99
(1H, m), 2.93 (1H, ABX, JAB ¼ 15.2 Hz, JBX ¼ 9.7 Hz), 2.8 (1H, ABX,
CDCl3)
d
: 207.8, 153.7, 147.7, 146.1, 136.6, 134.9, 133.4, 127.5, 126.6,
JAB ¼ 15.4 Hz, JBX ¼ 9.7 Hz). 13C NMR (125 MHz, CDCl3)
d: 207.3,
124.1, 121.9, 109.3, 108.3, 100.9, 49.1, 36.7, 32.1 ppm. HRMS: MHþ,
found: 267.1022. C17H15O3 requires 267.1021.
153.7, 153.6, 141.5, 136.4, 134.9, 127.5, 126.6, 124.1, 110.2, 106.4, 46.5,
32.5, 29.4 ppm. HRMS: MHþ, found: 213.0911. C14H13O2 requires
213.0910.
4.81. 2-(4-(trifluoromethyl)benzyl)-2,3-dihydro-1H-inden-1-one
(6o)
4.84. 2-(Thiophen-2-ylmethyl)-2,3-dihydro-1H-inden-1-one (6r)
Following the general procedure A, starting from enone 5o
(144 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6o was obtained as a white
powder (114 mg, 79%) after purification by flash column chroma-
tography on silica (eluent: pentane/AcOEt [90:10]); hmax (liquid
film) 2918, 2852, 1696, 1607, 1584, 1466, 1444, 1427, 1325, 1296,
1207, 1196, 1185, 1163, 1150, 1110, 1066, 1017, 1005, 953, 911, 876,
811, 788, 758, 744, 729, 717, 688, 642, 628, 611, 594 cmꢁ1.1H NMR
Following the general procedure A, starting from enone 5r
(113 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6r was obtained as a white
powder (92 mg, 81%) after purification by flash column chroma-
tography on silica (eluent: pentane/AcOEt [95:5]); nmax (liquid film)
3069, 2916, 2845, 1705, 1606, 1533, 1464, 1431, 1363, 1326, 1293,
1276, 1260, 1226, 1182, 1151, 1093, 1033, 1001, 979, 952, 895, 867,
850, 824, 800, 755, 743, 722, 693, 625, 559, 540, 514 cmꢁ1.1H NMR
(500 MHz, CDCl3)
d
: 7.79 (1H, d, J ¼ 10 Hz), 7.59 (1H, td, J ¼ 7.5,
(500 MHz, CDCl3)
d
: 7.78 (1H, d, J ¼ 7.5 Hz), 7.58 (1H, td, J ¼ 7.4,
1.0 Hz), 7.56 (2H, d, J ¼ 8.1 Hz), 7.41 (1H, td, J ¼ 7.9, 0.8 Hz), 7.36 (3H,
d, J ¼ 10 Hz), 3.43 (1H, ABX, JAB ¼ 14.1 Hz, JAX ¼ 4.3 Hz), 3.20 (1H,
ABX, JAB ¼ 17.2 Hz, JAX ¼ 7.9 Hz), 3.01 (1H, ABX, JAB ¼ 7.9 Hz,
JAX ¼ 4.0 Hz), 2.83 (1H, ABX, JAB ¼ 17.2 Hz, JAX ¼ 4.2 Hz), 2.77 (1H,
1.0 Hz), 7.43 (1H, dt, J ¼ 7.7, 0.8 Hz), 7.37 (1H, td, J ¼ 7.1, 0.7 Hz), 7.13
(1H, dd, J ¼ 5.1, 1.2 Hz), 6.92 (1H, q, J ¼ 3.4, 1.6 Hz), 6.86e6.85 (1H,
m), 3.57e3.51 (1H, m), 3.31 (1H, ABX, JAB ¼ 17 Hz, JAX ¼ 7.1 Hz),
3.04e2.97 (2H, m), 2.94 (1H, ABX, JAB ¼ 17 Hz, JAX ¼ 3.5 Hz) ppm. 13
C
ABX, JAB ¼ 14.1 Hz, JAX ¼ 10.1 Hz) ppm. 13C NMR (125 MHz, CDCl3)
d
:
NMR (125 MHz, CDCl3) d: 207.2, 153.7, 142.0, 136.5, 134.9, 127.5,
14

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
126.9, 126.6, 126.6, 124.1, 123.8, 49.1, 32.4, 31.2 ppm. HRMS: MHþ,
found: 229.0690. C14H13OS requires 229.0687.
References
[1] F.D. Klingler, Acc. Chem. Res. 40 (2007) 1367e1376.
[2] W.P. Hems, M. Groarke, A. Zanotti-Gerosa, G.A. Grasa, Acc. Chem. Res. 40
(2007) 1340e1347.
[3] N.B. Johnson, I.C. Lennon, P.H. Moran, J.A. Ramsden, Acc. Chem. Res. 40 (2007)
1291e1299.
4.85. 2-((1H-pyrrol-2-yl)methyl)-2,3-dihydro-1H-inden-1-one (6s)
[4] L.A. Saudan, Acc. Chem. Res. 40 (2007) 1309e1319.
[5] H. Shimizu, I. Nagasaki, K. Matsumura, N. Sayo, T. Saito, Acc. Chem. Res. 40
(2007) 1385e1393.
[6] H.-U. Blaser, M. Studer, Acc. Chem. Res. 40 (2007) 1348e1356.
[7] H.-U. Blaser, B. Pugin, F. Spindler, M. Thommen, Acc. Chem. Res. 40 (2007)
1240e1250.
[8] C. Scott Shultz, S.W. Krska, Acc. Chem. Res. 40 (2007) 1320e1326.
[9] a) D. Wang, D. Astruc, Chem. Rev. 115 (2015) 6621e6686 (For some examples
with platinum complexes, see);
Following the general procedure A, starting from enone 5s
(105 mg, 0.5 mmol), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6s was obtained as a yellow
powder (98 mg, 93%) after purification by flash column chroma-
tography on silica (eluent: Pentane/Ethyl acetate [90:10]; hmax
(liquid film) 3405, 3130, 2921, 2852, 1695, 1605, 1569, 1461, 1440,
1420,1400,1317,1294,1277,1205,1151, 1115,1086,1043, 1024,1005,
954, 896, 872, 841, 809, 793, 759, 743, 672, 655, 597, 577,
b) C. Wang, A. Pettman, J. Bacsa, J. Xiao, Angew. Chem. Int. Ed. 49 (2010)
7548e7552;
c) Y.-B. Hang, J.-J. Dai, X.-J. Deng, Y.-C. Qu, Q.-X. Guo, Y. Fu, ChemSusChem 4
(2011) 1578e1581;
d) S. Wang, H. Huang, C. Bruneau, C. Fischmeister, ChemSusChem 10 (2017)
4150e4154;
e) Y. Wei, C. Wang, X. Jiang, D. Xue, J. Li, J. Xiao, Chem. Commun. 49 (2013)
5408e5410;
564 cmꢁ1.1H NMR (500 MHz, CDCl3)
d: 8.81 (1H, s (NH)), 7.76 (1H, d,
J ¼ 7.6 Hz), 7.58 (1H, td, J ¼ 7.4, 1.1 Hz), 7.43 (1H, dt, J ¼ 7.6, 0.8 Hz),
7.37 (1H, td, J ¼ 7.3, 0.7 Hz), 6.67 (1H, t, J ¼ 1.0 Hz), 6.08 (1H, q,
J ¼ 2.8 Hz), 5.96 (1H, q, J ¼ 2.8 Hz), 3.37 (1H, ABX, JAB ¼ 16.6 Hz,
JAX ¼ 7.8 Hz), 3.09 (2H, ABX, JAB ¼ 15 Hz, JAX ¼ 6.5 Hz, JBX ¼ 5.5 Hz),
f) M. Zhu, Catal. Lett. 144 (2014) 1568e1572.
[10] C. Wang, X. Wu, J. Xiao, Chem. Asian J. 3 (2008) 1750e1770.
[11] a) D. Wei, C. Darcel, Chem. Rev. 119 (2019) 2550e2610;
3.03e2.96 (1H, m), 2.93 (1H, ABX, JAB ¼ 16.7 Hz, JAX ¼ 4.6 Hz). 13
C
NMR (125 MHz, CDCl3) d: 209.5, 153.8, 136.5, 135.1, 129.4, 127.5,
€
b) I. Bauer, H.-J. Knolker, Chem. Rev. 115 (9) (2015) 3170e3387.
[12] W. Liu, B. Sahoo, K. Junge, M. Beller, Acc. Chem. Res. 51 (2018) 1858e1869.
[13] W. Ai, R. Zhong, X. Liu, Q. Liu, Chem. Rev. 119 (2019) 2876e2953.
[14] G.A. Filonenko, R. van Putten, E.J.M. Hensen, E. Pidko, Chem. Soc. Rev. 47
(2018) 1459e1483.
126.6, 124.0, 117.4, 107.8, 106.7, 48.1, 32.6, 29.7, 28.4 ppm. HRMS:
MHþ, found: 212.1077. C14H14NO requires 212.1075.
[15] B.M. Trost, Science 219 (1983) 245e250.
4.86. 5b-pregnan-3,20-dione (6t) [19d]
[16] P.A. Shenvi, D.P. O'Malley, P.S. Baran, Acc. Chem. Res. 42 (2009) 530e541.
[17] For Some Examples, (see: ). a) T. Ohkuma, H. Ooka, T. Ikariya, R.J. Noyori, Am.
Chem. Soc. 117 (1995) 10417e10418;
Following the general procedure A, starting from progesterone
(0.5 mmol, 155 mg), Fe (5 mg, 0.01 mmol), Me3NO (1 mg,
0.0126 mmol) and potassium formate (210 mg, 2.5 mmol) for 24 h
at 45 ꢀC, the corresponding ketone 6t was obtained as as a single
diastereomer and as a white solid (47 mg, 30%), after purification by
flash column chromatography (CH2Cl2/EtOAc 1%). 1H NMR
b) X. Wang, Z. Han, Z. Wang, K. Ding, Angew. Chem. Int. Ed. 51 (2012)
936e940;
c) Y. Sasson, J. Blum, J. Org. Chem. 40 (1975) 1887e1896;
d) R. Farrar-Tobar, Z. Wei, H. Jiao, S. Hinze, J.G. de Vries, Chem. Eur J. 24 (2018)
2725e2734;
e) P. Puylaert, R. van Heck, Y. Fan, A. Spannenberg, W. Baumann, M. Beller,
J. Medlock, W. Bonrath, L. Lefort, S. Hinze, J.G. de Vries, Chem. Eur J. 23 (2017)
8473e8481.
(500 MHz, CDCl3)
d
: 2.69 (1H, t, J ¼ 14.3 Hz), 2.55 (1H, t, J ¼ 9.0 Hz),
[18] For Iron-Catalyzed Hydrogenation of Unsaturated Aldehydes, (see: ). a)
S. Fleischer, S. Zhou, K. Junge, M. Beller, Angew. Chem. Int. Ed. 52 (2013)
5120e5124;
2.34 (1H, td, J ¼ 14.3, 5.4 Hz) 2.21e2.14 (2H, m), 2.12 (3H, s),
2.09e2.00 (3H, m), 1.93e1.79 (2H, m), 1.73e1.61 (2H, m), 1.58e1.35
(7H, m), 1.30e1.19 (4H, m), 1.02 (3H, s), 0.63 (3H, s) ppm. 13C NMR
€
b) G. Wienhofer, F.A. Westerhaus, K. Junge, R. Ludwig, M. Beller, Chem. Eur J.
19 (2013) 7701e7707 (For manganese-catalyzed hydrogenation of unsatu-
rated aldehydes, see);
(125 MHz, CDCl3) d: 212.1, 208.5, 62.7, 55.6, 43.1, 41.3, 39.7, 38.3,
36.1, 35.9, 34.6, 34.5, 33.9, 30.5, 26.8, 25.5, 24.7, 23.4, 21.9, 21.6, 20.2,
12.4 ppm.
c) S. Elangovan, C. Topf, S. Fischer, H. Jiao, A. Spannenberg, W. Baumann,
R. Ludwig, K. Junge, M. Beller, J. Am. Chem. Soc. 138 (2016) 8809e8814 (For
copper-catalyzed hydrogenation of unsaturated aldehydes, see);
d) H. Shimizu, N. Sayo, T. Saito, Synlett (2009) 1295e1298 (For cobalt-
catalyzed hydrogenation of unsaturated carbonyl compounds, see);
e) G. Zhang, S.K. Hanson, Chem. Commun. 49 (2013) 10151e10153;
f) G. Zhang, B.L. Scott, S.K. Hanson, Angew. Chem. Int. Ed. 51 (2012)
12102e12106;
Declaration of competing interest
The authors declare that they have no known competing
financial interests or personal relationships that could have
appeared to influence the work reported in this paper.
€
g) S. Rosler, J. Obenauf, R. Kempe, J. Am. Chem. Soc. 137 (2015) 7998e8001;
h) C.-F. Huo, Y.-W. Li, M. Beller, H. Jiao, Organometallics 23 (2004) 2168e2478.
[19] a) W. Li, X.-F. Wu, Eur. J. Org Chem. (2015) 331e335 (and references cited
therein);
b) B. Ding, Z. Zhang, Y. Liu, M. Sugiya, T. Imamoto, W. Zhang, Org. Lett. 15
(2013) 3690e3693 (and references cited therein);
c) M. Shevlin, M.R. Friedfeld, H. Sheng, N.A. Pierson, J.M. Hoyt, L.-C. Campeau,
P.J. Chirik, J. Am. Chem. Soc. 138 (2016) 3562e3569;
d) A. Lator, S. Gaillard, A. Poater, J.-L. Renaud, Chem. Eur J. 24 (2018)
5770e5774.
Acknowledgments
We gratefully acknowledge financial support from the “Minis-
tere de la Recherche et des Nouvelles Technologies” (grant for L. B.),
ꢁ
[20] a) C.P. Casey, N.A. Strotman, S.E. Beetner, J.B. Johnson, D.C. Priebe, I.A. Guzei,
Organometallics 25 (2006) 1236e1244;
University of Caen Normandie (grant for N. J.), Normandie Uni-
ꢀ
ꢀ
versite, CNRS, “Region Normandie” (grant for Q. G. G.), and the
b) S. Garhwal, B. Maji, S. Semwal, J. Choudhury, Organometallics 37 (2018)
4720e4725.
LABEX SynOrg (ANR-11-LABX-0029). Ademe Agency is acknowl-
[21] L. Bonomo, L. Kermorvan, P. Dupau, ChemCatChem 7 (2015) 907e910.
[22] T. Zell, Y. Ben-David, D. Milstein, Catal. Sci. Technol. 5 (2015) 822e826;
(c) S. Mazza, R. Scopelliti, X. Hu, Organometallics 34 (2015) 1538e1545;
€
6 (2016)
ꢀ
ꢀ ꢀ
edged for a grant to S. C. and Cooperation Française-Senegal for a
grant to D. N. A.P. is a Serra Húnter Fellow and thanks ICREA
Academia prize 2019 and the Spanish MICINN for project PGC2018-
097722-B-I00.
(d) N. Gorgas, B. Stoger, L.F. Veiros, K. Kirchner, ACS Catal.
2664e2672.
[23] Y. Li, J.A. Krause, H. Guan, Organometallics 37 (2018) 2147e2158.
€
[24] M. Glatz, B. Stoger, D. Himmelbauer, L.F. Veiros, K. Kirchner, ACS Catal. 8
(2018) 4009e4016.
Appendix A. Supplementary data
[25] For a recent chemoselective hydrogenation with a cyclopentadienyl iron
ꢀ
carbonyl complex, see A. Lator, Q. Gaignard Gaillard, D. S Lohier Merel, J.-
F. Gaillard, S. Poater, A. Renaud J L, J. Org. Chem. 84 (2019) 6813e6829.
[26] For Iron Complexes-Catalyzed Hydrogen Transfer Reaction, (see):. a)
Supplementary data to this article can be found online at
https://doi.org/10.1016/j.tet.2021.132187.
15

S. Coufourier, D. Ndiaye, Q.G. Gaillard et al.
Tetrahedron xxx (xxxx) xxx
G. Metzker, R.M.P. Dias, A.C.B. Bartoloso, Chemistry 3 (2018) 368e372;
b) E. Petricci, N. Santillo, D. Castagnolo, E. Cini, M. Taddei, Adv. Synth. Catal.
360 (2018) 2560e2565;
f) R. Hodgkinson, A. Del Grosso, G. Clarkson, M. Wills, Dalton Trans. 45 (2016)
3992e4005;
g) A. Del Grosso, A.E. Chamberlain, G. Clarkson, M. Wills, Dalton Trans. 47
(2018) 1451e1470.
c) S. Mazza, R. Scopelliti, X. Hu, Organometallics 34 (2015) 1538e1545;
€
d) G. Wienhofer, I. Sorribes, A. Boddien, F.A. Westerhaus, K. Junge, H. Junge,
[31] a) L. Bettoni, S. Gaillard, J.-L. Renaud, Org. Lett. 22 (2020) 2064e2069;
b) L. Bettoni, S. Gaillard, J.-L. Renaud, Org. Lett. 21 (2019) 8404e8408;
c) L. Bettoni, C. Seck, M.D. Mbaye, S. Gaillard, J.-L. Renaud, Org. Lett. 21 (2019)
3057e3061;
R. Llusar, Beller M. J. Am. Chem. Soc. 133 (2011) 12875e12879;
€
e) G. Wienhofer, F.A. Westerhaus, K. Junge, Beller M. J. Organomet. Chem. 744
(2013) 156e159.
[27] For Iron Complexes-Catalyzed Enantioselective Reduction of C¼O Bonds via a
Hydrogen Transfer Reaction, (see):. a) Zhou S. Fleischer, S. Junge, K. Das,
S. Addis, D. Beller, M. Angew, Chem. Int. Ed. 49 (2010) 8121e8125;
b) Y.-Y. Li, S.-L. Yu, W.-Y. Shen, J.-X. Gao, Acc. Chem. Res. 48 (2015)
2587e2598;
d) A. Lator, S. Gaillard, A. Poater, J.-L. Renaud, Org. Lett. 20 (2018) 5985e5990;
e) C. Seck, M.D. Mbaye, S. Gaillard, J.-L. Renaud, Adv. Synth. Catal. 360 (2018)
4640e4645;
f) C. Seck, M.D. Mbaye, S. Coufourier, A. Lator, J.-F. Lohier, A. Poater, T.R. Ward,
S. Gaillard, J.-L. Renaud, ChemCatChem 9 (2017) 4410e4416.
€
ꢀ
c) R. Bigler, R. Huber, M. Stockli, A. Mezzetti, ACS Catal. 6 (2016) 6455e6464;
[32] a) T.-T. Thai, D.S. Merel, A. Poater, S. Gaillard, J.-L. Renaud, Chem. Eur J. 21
d) R. Bigler, R. Huber, A. Mezzetti, Angew. Chem. Int. Ed. 54 (2015)
5171e5174;
e) L. De Luca, A. Mezzetti, Angew. Chem. Int. Ed. 56 (2017) 11949e11953;
f) W. Zuo, D.E. Prokopchuk, A.J. Lough, R.H. Morris, ACS Catal. 6 (2016)
301e314;
(2015) 7066e7070;
b) A. Pagnoux-Ozherelyeva, N. Pannetier, D.M. Mbaye, S. Gaillard, J.-L. Renaud,
Angew. Chem. Int. Ed. 51 (2012) 4976e4980;
c) S. Moulin, H. Dentel, A. Pagnoux-Ozherelyeva, S. Gaillard, A. Poater,
L. Cavallo, J.-F. Lohier, J.-L. Renaud, Chem. Eur J. 19 (2013) 17881e17890.
[33] a) T.-Y. Luh, Coord. Chem. Rev. 60 (1984) 255e276;
g) P.O. Lagaditis, A.J. Lough, R.H. Morris, J. Am. Chem. Soc. 133 (2011)
9662e9665;
€
b) H.-J. Knolker, J. Prakt. Chem. 338 (1996) 190e192.
h) A.A. Mikhailine, M.I. Maishan, R.H. Morris, Org. Lett. 14 (2012) 4638e4641;
i) Z. Zhang, N.A. Butt, M. Zhou, D. Liu, W. Zhang, Chin. J. Chem. 36 (2018)
443e454.
[34] For the Use of Me3NO with Cyclopentadienone Iron Tricarbonyl Complexes,
(see: ). a) Moyer S.A. Funk, T. Tetrahedron Lett. 51 (2010) 5430e5433;
b) T.C. Johnson, G.J. Clarkson, M. Wills, Organometallics 30 (2011)
1859e1868;
[28] For a recent review on cyclopentadienone iron complexes, see: Pignataro, L.;
Gennari, C. Eur. J. Org. Chem. 2020, 3192e3205.
[29] Enantioselective Reductions Promoted by (Cyclopentadienone)iron Com-
c) S. Coufourier, S. Gaillard, G. Clet, C. Serre, M. Daturi, J.-L. Renaud, Chem.
Commun. 55 (2019), 4977e4880;
€
plexes: for
a
Review, (see):. a) Piarulli U. Vailati Fachinia, S. Pignataro,
d) H.-J. Knolker, J. Heber, Synlett (1993) 924e926;
€
L. Chimia 71 (2017) 580e585;
e) H.-J. Knolker, E. Baum, J. Heber, Tetrahedron Lett. 42 (1995) 7647e7650;
€
b) P. Gajewski, M. Renom-Carrasco, S. Vailati Facchini, L. Pignataro, L. Lefort,
J.G. de Vries, R. Ferraccioli, A. Forni, Piarulli U. Gennari, C. Eur. J. Org. Chem.
(2015) 1887e1893;
f) H.-J. Knolker, E. Baum, H. Goesmann, R. Klauss, Angew. Chem. Int. Ed. 38
(1999) 2064e2066;
€
g) H.-J. Knolker, J. Heber, C.H. Mahler, Synlett (1992) 1002e1004.
c) P. Gajewski, M. Renom-Carrasco, Vailati Facchini S. Pignataro, L. Lefort, L. de
Vries, J.G. Ferraccioli, R. Forni, A. Piarulli, U. Gennari, C. Eur. J. Org. Chem.
(2015) 5526e5536;
d) X. Bai, M. Cettolin, G. Mazzoccanti, M. Pierini, U. Piarulli, V. Colombo, Dal
Corso A. Pignataro, L. Gennari, C. Tetrahedron 75 (2019) 1415e1424;
e) C.A.M.R. van Slagmaat, K.C. Chou, L. Morick, D. Hadavi, B. Blom, S.M.A. De
Wildeman, Catalysts 9 (2019) 790e813;
f) D.S. Merel, S. Gaillard, T.R. Ward, J.-L. Renaud, Catal. Lett. 146 (2016)
564e596;
g) M. Cettolin, X. Bai, D. Lübken, M. Gatti, S. Vailati Facchini, U. Piarulli,
L. Pignataro, C. Gennari, Eur. J. Org Chem. 4 (2019) 647e654;
[35] C.P. Casey, H. Guan, J. Am. Chem. Soc. 129 (2007) 5816e5817;
b) C.P. Casey, H. Guan, J. Am. Chem. Soc. 131 (2009) 2499e2507.
[36] C. Bianchini, E. Farnetti, M. Graziani, M. Peruzzini, A. Polo, Organometallics 12
(1993) 3753e3761.
[37] M.D. Bhor, A.G. Panda, S.R. Jagtap, B.M. Bhanage, Catal. Lett. 124 (2008)
157e164.
[38] D. Ndiaye, S. Coufourier, M. Diagne Mbaye, S. Gaillard, J.-L. Renaud, Molecules
25 (2020) 421e431.
[39] S.S. Kotha, N. Sharma, G. Sekar, Adv. Synth. Catal. 358 (2016) 1694e1698.
[40] M. Yamagushi, T. Takata, T. Endo, J. Org. Chem. 55 (1990) 1490e1492.
[41] S. Chandrasekhar, A. Shrinidhi, Synth. Commun. 44 (2014) 2051e2056.
[42] P.T. Kirinde Arachchige, H. Lee, C. Yi, S. J. Org. Chem 83 (2018) 4932e4947.
[43] Y. Peng, Y.-H. Fan, S.-Y. Li, B. Li, J. Xue, Q.-H. Deng, Org. Lett. 21 (2019)
8389e8394.
€
€
h) A. Berkessel, S. Reichau, A. von der Hoh, N. Leconte, J.-M. Neudorfl, Or-
ganometallics 30 (2011) 3880e3887.
[30] For Cyclopentadienone Iron Complexes-Catalyzed Hydrogen Transfer Reac-
tion, (see):. a) T.N. Plank, J.L. Drake, D.K. Kim, T.W. Funk, Adv. Synth. Catal. 354
(2012) 597e601;
[44] M. Vellakkaran, M.M.S. Andappan, N. Kommu, Eur. J. Org Chem. (2012)
4694e4698.
b) T.W. Funk, A.R. Mahoney, R.A. Sponenburg, K.P. Zimmerman, D.K. Kim,
E.E. Harrison, Organometallics 37 (2018) 1133e1140;
[45] S. Park, T.M. Kadayat, K.Y. Jun, T.B.T. Magar, G. Bist, A. Shrestha, E.S. Lee,
Y. Kwon, Eur. J. Med. Chem. 125 (2017) 14e28.
c) H.-J. Pan, T.W. Ng, Y. Zhao, Org. Biomol. Chem. 14 (2016) 5490e5493;
d) S.V. Facchini, M. Cettolin, X. Bai, G. Casamassima, L. Pignataro, C. Gennari,
U. Piarulli, Adv. Synth. Catal. 360 (2018) 1054e1059;
e) J.P. Hopewell, J.E.D. Martins, T.C. Johnson, J. Godfrey, M. Wills, Org. Biomol.
Chem. 10 (2012) 134e145;
[46] R. Bansal, G. Narang, C. Zimmer, R.W. Hartmann, Med. Chem. Res. 20 (2011)
661e669.
[47] S. Kayal, S. Mukherjee, Org. Biomol. Chem. 14 (2016) 10175e10179.
[48] M.S. Nel, A. Petzer, J.P. Petzer, L.J. Legoabe, Bioorg. Chem. 69 (2016) 20e28.
16