Reduction of nitriles into aldehydes using a TMDS/V(O)(OiPr)3 reducing system

Article abstract of DOI:10.1016/j.tetlet.2013.10.065

A simple and convenient method for the chemoselective reduction of nitriles into aldehydes using a 1,1,3,3-tetramethyldisiloxane (TMDS)/ triisopropoxyvanadium(V) oxide reducing system is described. Aromatic as well as aliphatic nitriles are reduced into the corresponding aldehydes in moderate to good yields.

Full text of DOI:10.1016/j.tetlet.2013.10.065

Tetrahedron Letters 55 (2014) 23–26
Contents lists available at ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Reduction of nitriles into aldehydes using a TMDS/V(O)(OiPr)3
reducing system
Stéphane Laval a, Wissam Dayoub a, Leyla Pehlivan a, Estelle Métay a, Dominique Delbrayelle b,
Gérard Mignani c, Marc Lemaire a,
⇑
a Laboratoire de Catalyse, Synthèse et Environnement, Institut de Chimie et Biochimie Moléculaires et Supramoléculaires (ICBMS), CNRS, UMR 5246, Université Claude-Bernard Lyon
1, campus de la Doua, 43 boulevard du 11 novembre 1918, bât. Curien—CPE, 3e étage, 69622 Villeurbanne, France
b Minakem SAS, 145 Chemin des Lilas, 59310 Beuvry la Foret, France
c Rhodia, Lyon Research Center, 85, Avenue des Frères Perret, BP 62, 69192 Saint-Fons Cedex, France
a r t i c l e i n f o
a b s t r a c t
Article history:
A simple and convenient method for the chemoselective reduction of nitriles into aldehydes using a
1,1,3,3-tetramethyldisiloxane (TMDS)/triisopropoxyvanadium(V) oxide reducing system is described.
Aromatic as well as aliphatic nitriles are reduced into the corresponding aldehydes in moderate to good
yields.
Received 13 September 2013
Revised 8 October 2013
Accepted 11 October 2013
Available online 21 October 2013
Ó 2013 Elsevier Ltd. All rights reserved.
Keywords:
Nitriles
Aldehydes
Reduction
1,1,3,3-Tetramethyldisiloxane (TMDS)
Vanadium
Introduction
organic molecules and also for the reduction of unsaturated func-
tions. Easy to handle and readily available, they have found appli-
The reduction of nitriles to aldehydes is a challenge in synthetic
organic chemistry. Indeed, the chemoselective reduction of the
unreactive cyano group presents a difficulty. More precisely, the
imine intermediate that produces the aldehyde is usually much
more reactive than the nitrile and thus conducts to the over-re-
duced amine. Since the Stephen Reduction,1 conventional methods
for this transformation use strong hydride donors such as Li(OEt)3-
AlH,2 DIBAL-H,3 and their derivatives.4–6 Borohydride reagents
have also been reported for this reduction but less than aluminum
hydrides.7 However, the previous methods suffer from serious
drawbacks such as the use of potentially hazardous water-soluble
solvents, exothermic workup, handling under anhydrous condi-
tions, and production of stoichiometric amounts of salts as by-
products. Other reducing systems have also been reported includ-
ing the reductions by photo-irradiation8 or with the association of
PtO2/aqueous formic acid,9 Ni-Raney/hydrazine hydrate,10 Ni-
Raney/sodium hypophosphite,11 nickel-based bimetallic systems
in acidic medium,12 and Ru- and Pt-loaded zeolites.13
cations for the reduction of a large number of functional groups.14
Nevertheless, probably because of the robustness of the cyano
group, only few examples concerning the mono-silylation of the
carbon-nitrogen triple bond have been published. In 1966, Calas
et al. first reported the zinc catalyzed addition of trialkylhydrosi-
lane on nitriles to yield N-silylimines, protected forms of
aldehydes.15 In 1970, A. J. Chalk published the 1,4-addition of
HSiClMe2 on methacrylonitrile in the presence of dicobalt
octacarbonyl.16 The reaction afforded the corresponding N,N-
disilylenamine in 20% yield after 6 days. Corriu studied the
combination of bis-silanes and Fe(CO)5 for the stoichiometric
hydrosilylation of aliphatic nitriles into N,N-disilylenamines under
UV-irradiation.17 Bis-silanes were also associated with Ni,18a Pt,18b
and Rh18c catalysts to reduce nitriles with
a-H into cyclic N-silylen-
amines and aromatic nitriles into cyclic N-silylimines. Ru,19a,b
W,19c,d and Mo19d,e complexes bearing a Si–H moiety have been de-
signed for the stoichiometric hydrosilylation of nitriles but few
examples have been published and yields are low to moderate. Re-
cently, Nikonov and co-workers reported the reduction of nitriles
into imines with hydrosilanes in the presence of Mo and Ru cata-
lysts.20 Whereas the Mo-complex catalyzed slowly the hydrosilyla-
tion of benzonitrile in the presence of PhSiH3,20a the
[Cp(iPr3P)Ru(NCCH3)2][B(C6F5)4]/Me2PhSiH system reduced at
Over the past decade, hydrosilanes have attracted more atten-
tion since they can be used for the introduction of silyl groups in
⇑
Corresponding author. Tel.: +33 472 43 14 07; fax: +33 472 43 14 08.
E-mail address: marc.lemaire.chimie@univ-lyon1.fr (M. Lemaire).
0040-4039/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetlet.2013.10.065

24
S. Laval et al. / Tetrahedron Letters 55 (2014) 23–26
room temperature aliphatic and aromatic nitriles into N-silyli-
mines in good to excellent yields.20b Nevertheless, these methodol-
ogies use expensive hydrosilanes known to be hazardous and
dangerous by generating toxic, pyrophoric SiH4 gas.21
the conversion of the starting material from 35% to 55% and 100%,
respectively (Table 1, entries 1, 2, and 5). With intermediate quan-
tities 12.0 and 16.0 Si–H/CN, 1a was not fully consumed (Table 1,
entries 3 and 4). In all the experiments, aldehyde 2a is the major
product but the chemoselectivity of the reduction is decreased
by the presence of imine 3a which indicates the formation of 4-
chlorobenzylamine as the co-product. The best result was obtained
with 20.0 Si–H/CN of TMDS where aldehyde 2a was formed in 75%
GC yield (Table 1, entry 5). Using the same amount of TMDS, the
conversion drastically dropped when decreasing the loading of
vanadium catalyst even in the presence of phosphorus ligands
(Table 1, entries 6–8).
The efficiency of other vanadium complexes with different oxi-
dation states such as V(O)Cl3 (1.0 equiv), V(acac)3 (1.0 equiv), VF4
(1.0 equiv), V(O)(acac)2 (1.0 equiv), and N,N0-bis(salicylidene)-o-
phenylenediamine vanadium(IV) oxide complex (0.02 equiv) was
also investigated for the reduction of 1a in association with 20.0
Si–H/CN of TMDS. Nevertheless, they proved to be inefficient since
1a was totally recovered after 20 h reaction and even after longer
reaction time.
For several years now, our group has been studying the behav-
ior of 1,1,3,3-tetramethyldisiloxane (TMDS) as a safer source of hy-
drides for the reduction of phosphine oxides,22a–c amides,22d,e
nitro,22f,g acetals,22h–j ketones,22k and carboxylic acids,22l in the
presence of an appropriate transition metal. Associated with a rel-
atively inexpensive titanium(IV) isopropoxide, TMDS is able to re-
duce nitriles into amines.23 Recently, we have shown that the
combination of TMDS and V(O)(OiPr)3 is efficient for the reduction
of esters into alcohols.24 To the best of our knowledge, it was the
first time that a vanadium complex was associated with an hydro-
siloxane for the reduction of an organic function. Moreover, TMDS
was never reported for the reduction of nitriles into aldehydes.
Herein, we extend the scope of the TMDS/V(O)(OiPr)3 reducing sys-
tem to the chemoselective reduction of aromatic and aliphatic ni-
triles into aldehydes.
Consequently, a reducing system composed of 20.0 Si–H/CN of
TMDS, 1.0 equiv of V(O)(OiPr)3 in toluene at 60 °C for 20 h gave sat-
isfactory results for the chemoselective reduction of nitriles into
aldehydes. Under these reaction conditions, we extended the
reduction to other aromatic as well as aliphatic nitriles (Table 2).25
Aromatic nitriles 1b and 1c bearing a methoxy and a methyl
group at the para-position were reduced into the corresponding
aldehydes 2b and 2c in 67% and 63% GC yields, respectively (Ta-
ble 2, entries 2 and 3). In the case of 1c, after 24 h reduction, the
crude mixture was hydrolyzed with an aqueous solution of
orthophosphoric acid to liberate aldehyde 2c in the organic layer.
Without further purification, 2c reacted with tert-butylcarbazate
to give the corresponding hydrazone in 62% isolated yield
(Scheme 1).
The p-tolyl group at the ortho-position of nitrile 1d did not af-
fect the reduction and aldehyde 2d was obtained in 70% GC yield
(Table 2, entry 4). Reduction of 1-cyanonaphthalene 1e gave 1-
naphthaldehyde 2e in 60% GC yield (Table 2, entry 5). After acidic
treatment using aqueous H3PO4 followed by flash column chro-
matography, 2d and 2e were isolated in 60% and 45% yields,
respectively. The long chain aliphatic nitrile 1f was reduced in
the corresponding fatty aldehyde 2f in 84% GC yield (Table 2, en-
try 6). 1-Cyclohexenylacetonitrile 1g bearing a non-conjugated
C@C was not reduced into the expected aldehyde. The volatile
and more stable conjugated 2-cyclohexylidene-acetaldehyde 2g,
resulting from the rearrangement of the double bond, was
Results and discussion
In our previous work, we have shown that a reducing system
composed of 1.0 mol % of V(O)(OiPr)3 and 4.0 Si–H of TMDS in tol-
uene at 100 °C was efficient to reduce a large number of esters into
alcohols.24 However, under these reaction conditions, reduction of
p-cyanomethylbenzoate failed because of the presence of the
nitrogen atom. The cyano group might coordinate the metal and
thus block the reduction. Consequently, we concentrated our ef-
forts in order to determine the feasibility of reducing a cyano group
by a TMDS/V(O)(OiPr)3 reducing system and investigated the
reduction of 4-chlorobenzonitrile 1a as a model substrate. Depend-
ing on the reaction conditions and after an acid-base treatment of
the crude mixture, two products were detected in the organic layer
by GC–MS analysis: 4-chlorobenzaldehyde 2a which comes from
the hydrolysis of an N-silylimine intermediate and imine 3a (Ta-
ble 1). It is important to note that imine 3a is not a direct product
of the reduction but it results from the condensation of 4-chloro-
benzylamine (which comes from the hydrolysis of an N,N-disilyl-
amine intermediate) with aldehyde 2a after a basic treatment.
Consequently, imine 3a implies the formation of 4-chlorobenzyl-
amine as a minor product of the reduction of 1a.
First reactions were conducted in toluene at 60 °C for 20 h with
1.0 equiv of V(O)(OiPr)3 and it appeared that the amount of TMDS
is essential to reach complete conversion of 1a. Indeed, increasing
the quantity of hydrides from 6.0 to 8.0 and 20.0 Si–H/CN increased
Table 1
Reduction of 4-chlorobenzonitrile 1a under various TMDS-V(O)(OiPr)3 reaction conditions
TMDS
V(O)(OiPr)3
1) HCl 1M aq.
O
N
N
Cl
Cl
+
H
Cl
Cl
toluene
60°C, 20h
2) NaOH 3M aq.
1a
2a
3a
Entry
TMDS (moles Si–H/mole CN)
Moles V(O)(OiPr)3/mole CN
Ligandb
Conv.a (%)
Ratio 2a:3aa
1
2
3
4
5
6
7
8
6.0
8.0
1.0
1.0
1.0
1.0
1.0
0.5
0.2
0.2
—
—
—
—
—
—
35
55
86
87
100
28
32: 3
52: 3
60:26
64:23
67:33
26:2
12.0
16.0
20.0
20.0
20.0
20.0
(Ph)3P@O
(Ph)3P
24
17
16:8
17:0
a
Determined by GC–MS analysis of the organic layer after a first acidic treatment (aq 1 m HCl) followed by basification (aq 3 m NaOH until pH >11).
0.6 equiv/CN.
b

S. Laval et al. / Tetrahedron Letters 55 (2014) 23–26
25
Table 2
Reduction of aromatic and aliphatic nitriles into aldehydes using a TMDS/V(O)(OiPr)3 reducing systema
Entry Nitrile
Aldehyde
% GC yield (%
isolated
Entry Nitrile
Aldehyde
% GC yield (%
isolated
yield)b
yield)b
O
O
N
N
N
O
Cl
O
1
2
1a
1b
2a 75
6
1f
2f
84
10
Cl
O
10
O
O
N
N
2b 67
7
8
1g
2g 81
O
N
O
N
3
4
1c
2c 63 (62)c
1h
1i
2h 40d
N
O
1d
2d 70 (60)
2e 60 (45)
9
2i
2j
10e
N
O
O2N
O2N
N
H2N
N
5
1e
10
11
1j
30f,g
O
N
1k
2k No reactionh
O2N
a
b
c
Reaction conditions: nitrile (1.0 equiv), TMDS (20.0 Si–H/CN, 10.0 equiv), V(O)(OiPr)3 (1.0 equiv/CN), toluene, 60 °C, 20 h unless otherwise indicated.
Starting nitriles were completely reduced and the remaining % GC yields correspond to the corresponding primary amines unless otherwise stated.
Isolated as hydrazone.
Starting material 1h is recovered in 60%.
d
e
f
Starting material 1i is recovered in 90%.
After 20 h reaction, additional amounts of TMDS (20.0 Si–H/CN) and V(O)(OiPr)3 (1.0 equiv/CN) were added with 24 h extra stirring.
g
h
Estimated by 1H NMR.
Reactions carried out using toluene (heterogeneous) or THF (homogeneous) as solvent.
1) TMDS (20.0 Si-H/CN)
APTS (1.0 mol%)
Pyridine (1.0 mol%)
V(O)(OiPr)3 (1.0 equiv.)
O
toluene, 60°C, 20h
O
N
N
NH
O
2) aq. H3PO4, 2-3h
HN
H2N
O
62%
(1.0 equiv.)
Scheme 1.
obtained in 81% GC yield (Table 2, entry 7). The trans-cinnamonit-
rile 1h bearing a conjugated C@C was partially reduced after 20 h
reaction (Table 2, entry 8). This result can be explained by the
stabilization of the conjugated system. In addition, the C@C of
1g and 1h was not reduced under these reaction conditions.
Reduction of phenylacetonitrile 1i was sluggish since only 10%
of 1i reacted after 20 h to give chemoselectively 2i in 10% GC
yield (Table 2, entry 9).
High-valent oxo-vanadium(V) complex is usually employed in
oxidation processes whereas reduction reactions involve low oxi-
dation state vanadium(II) compounds.26 The reversal use of high
oxidation oxo-metal complexes in reducing reactions is extremely
rare and to the best of our knowledge we were the first group that
reported the use of oxo-vanadium(V) complex that catalyzed
hydrosilylation reaction.24 At this stage, it is difficult to propose a
detailed mechanistic pathway but how the vanadium complex
activates the Si–H bond remains an important question.
A possible pathway might be a single electron transfer (SET)
reaction between the Si–H and the oxo-vanadium(V) complex that
reduces the vanadium(V) into vanadium(IV) and produces a silyl-
radical which then reacts with the nitrile. This hypothesis comes
from the mechanistic highlights published by Petit et al. in our lab-
oratory for the reduction of phosphine oxides to phosphines using
the TMDS/Ti(OiPr)4 reducing system.22b,27 It was demonstrated
that a SET between the hydrosiloxane and the titanium(IV) gener-
ates a Ti(III) species and a silyl-radical which then reduces the
phosphine oxide. In the present case, two observations might sug-
gest a similar mechanism: (1) the blue dark color that appears in
the reaction flask during the reduction which could be attributed
As we have already noted in our previous report,24 the presence
of a nitro group in the substrate caused difficulties in the reduction.
Indeed, the cyano group of compounds 1j and 1k was not reduced
(Table 2, entries 10 and 11). After an additional amount of the
TMDS/V(O)(OiPr)3 reducing system and 24 h extra time, only par-
tial reduction of the nitro group of 1j into the corresponding amine
was observed in 30% 1H NMR yield (Table 2, entry 10). However,
neither the nitro group nor the cyano group of 1k was reduced
even after longer reaction time and additional amount of the
reducing system (Table 2, entry 11). Moreover, in this case, the
same results were obtained by performing the reaction in toluene
(heterogeneous system) or THF (homogeneous system) as the
solvent.

26
S. Laval et al. / Tetrahedron Letters 55 (2014) 23–26
15. Calas, R. Sur Quelques Aspects de la Réactivité des Hydrogénosilanes en Chimie
Organique 1966, 61–79.
16. Chalk, A. J. J. Organometal. Chem. 1970, 21, 207–213.
to the presence of vanadium(IV) and (2) the redox properties of
vanadium to induce one-electron transfer.26
At this stage, more information is needed to determine the type
of activation of the Si–H bond. Mechanism of hydrosilylation is of-
ten complicated and depends strongly on the nature of the metal.
Consequently mechanistic study is still underway in the labora-
tory. Nevertheless we assume that the hydrosiloxane reduces the
nitrile into an N-silylimine which is hydrolyzed into the desired
aldehyde. Passage through an N-silylimine can explain the pres-
ence of the primary amine by over-reduction.
17. (a) Corriu, R. J. P.; Moreau, J. J. E.; Pataud-Sat, M. Organometallics 1985, 4, 623–
629; (b) Corriu, R. J. P.; Moreau, J. J. E.; Pataud-Sat, M. J. Org. Chem. 1981, 46,
3374–3376; (c) Corriu, R. J. P.; Moreau, J. J. E. J. Chem. Soc., Chem. Commun.
1980, 278–279.
18. (a) Kim, J.; Kang, Y.; Lee, J.; Kong, Y. K.; Gong, M. S.; Kang, S. O.; Ko, J.
Organometallics 2001, 20, 937–944; (b) Reddy, N. P.; Uchimaru, Y.;
Lautenschlager, H.-J.; Tanaka, M. Chem. Lett. 1992, 45–48; (c) Corriu, R. J. P.;
Moreau, J. J. E.; Pataud-Sat, M. J. Organometal. Chem. 1982, 228, 301–308.
19. (a) Ochiai, M.; Hashimoto, H.; Tobita, H. Angew. Chem., Int. Ed. 2007, 46, 8192–
8194; (b) Hashimoto, H.; Aratani, I.; Kabuto, C.; Kira, M. Organometallics 2003,
22, 2199–2201; (c) Watanabe, T.; Hashimoto, H.; Tobita, H. J. Am. Chem. Soc.
2006, 128, 2176–2177; (d) Komuro, T.; Begum, R.; Ono, R.; Tobita, H. Dalton
Trans. 2011, 40, 2348–2357; (e) Khalimon, A. Y.; Simionescu, R.; Kuzmina, L. G.;
Howard, J. A. K.; Nikonov, G. I. Angew. Chem., Int. Ed. 2008, 47, 7701–7704.
20. (a) Peterson, E.; Khalimon, A. Y.; Simionescu, R.; Kuzmina, L. G.; Howard, J. A.
K.; Nikonov, G. I. J. Am. Chem. Soc. 2009, 131, 908–909; (b) Gutsulyak, D. V.;
Nikonov, G. I. Angew. Chem., Int. Ed. 2010, 49, 7553–7556.
Conclusions
In summary, we reported herein the first reducing system
employing the hydrosiloxane TMDS activated by a oxovana-
dium(V) complex which is able to reduce nitriles into aldehydes.
The reaction proceeds in toluene at 60 °C with both aromatic and
aliphatic nitriles to give the corresponding aldehydes in moderate
to good yields. The number of hydrides and the difficulty to reduce
substrates containing a nitro group might constitute limitations of
this reducing system. Nevertheless, the ease of this method consti-
tutes an alternative to the existing ones and the use of high-valent
oxo-vanadium(V) complex can open up a new class of high oxida-
tion transition-metal complexes for reduction reactions.
21. Safety alerts have been published concerning hazards and risks of hydrosilanes
related to the unexpected generation of silane, SiH4, an extremely dangerous,
toxic, pyrophoric and explosive gas. See: (a) Wells, A. S. Org. Process Res. Dev.
2010, 14, 484; (b) Berk, S. C.; Buchwald, S. L. J. Org. Chem. 1993, 58, 3221. and J.
Org. Chem. 1992, 57, 3751–3753.
22. (a) Pehlivan, L.; Métay, E.; Delbrayelle, D.; Mignani, G.; Lemaire, M. Tetrahedron
2012, 68, 3151–3155; (b) Petit, C.; Favre-Réguillon, A.; Albela, B.; Bonneviot, L.;
Mignani, G.; Lemaire, M. Organometallics 2009, 28, 6379–6382; (c) Berthod, M.;
Favre-Réguillon, A.; Mohamad, J.; Mignani, G.; Docherty, G.; Lemaire, M. Synlett
2007, 1545–1548; (d) Laval, S.; Dayoub, W.; Pehlivan, L.; Métay, E.; Favre-
Réguillon, A.; Delbrayelle, D.; Mignani, G.; Lemaire, M. Tetrahedron Lett. 2011,
52, 4072–4075; (e) Laval, S.; Dayoub, W.; Favre-Réguillon, A.; Demonchaux, P.;
Mignani, G.; Lemaire, M. Tetrahedron Lett. 2010, 51, 2092–2094; (f) Pehlivan, L.;
Métay, E.; Laval, S.; Dayoub, W.; Demonchaux, P.; Mignani, G.; Lemaire, M.
Tetrahedron 2011, 67, 1971–1976; (g) Pehlivan, L.; Métay, E.; Laval, S.; Dayoub,
W.; Demonchaux, P.; Mignani, G.; Lemaire, M. Tetrahedron Lett. 2010, 51, 1939–
1941; (h) Zhang, Y.-J.; Dayoub, W.; Chen, G.-R.; Lemaire, M. Green Chem. 2011,
13, 2737–2742; (i) Zhang, Y.-J.; Dayoub, W.; Chen, G.-R.; Lemaire, M. Eur. J. Org.
Chem. 2012, 1960–1966; (j) Shi, Y.; Dayoub, W.; Chen, G.-R.; Lemaire, M.
Tetrahedron Lett. 2011, 52, 1281–1283; (k) Pehlivan, L.; Métay, E.; Boyron, O.;
Demonchaux, P.; Mignani, G.; Lemaire, M. Eur. J. Org. Chem. 2011, 4687–4692;
(l) Pehlivan, L.; Métay, E.; Delbrayelle, D.; Mignani, G.; Lemaire, M. Eur. J. Org.
Chem. 2012, 4689–4693.
Acknowledgments
This work was financially supported by the ‘Fond Unique Inter-
ministeriel’ (FUI). The authors are grateful for the access to MS and
NMR facilities at the Université de Lyon 1—La Doua—France.
References and notes
23. Laval, S.; Dayoub, W.; Favre-Réguillon, A.; Berthod, M.; Demonchaux, P.;
Mignani, G.; Lemaire, M. Tetrahedron Lett. 2009, 50, 7005–7007.
1. (a) Stephen, H. J. Chem. Soc. 1925, 127, 1874–1877; (b) Kürti, L.; Czako, B. In
Strategic Applications of Named Reaction in Organic Synthesis; Elsevier Academic
Press, 2005; pp 430–431. and references cited herein (p. 685).
2. Brown, H. C.; Garg, C. P. J. Am. Chem. Soc. 1964, 86, 1085–1089.
3. Wells, G. J.; Yan, T.-H.; Paquette, L. A. J. Org. Chem. 1984, 49, 3604–3609.
4. (a) Cha, J. S.; Chang, S. W.; Kwon, O. O.; Kim, J. M. Synlett 1996, 165–166; (b)
Brown, H. C.; Schoaf, C. J.; Garg, C. P. Tetrahedron Lett. 1959, 1, 9–10.
5. (a) Cha, J. S.; Jang, S. H.; Kwon, S. Y. Bull. Korean Chem. Soc. 2002, 23, 1697–
1698; (b) Cha, J. S. Bull. Korean Chem. Soc. 1992, 13, 670–676; (c) Yoon, N. M.;
Kim, S. K.; Kyong, Y. S. Bull. Korean Chem. Soc. 1986, 7, 323–325.
6. (a) Choi, Y. M.; Yoo, M.; An, D. K. Bull. Korean Chem. Soc. 2010, 31, 473–474; (b)
Choi, Y. M.; Choi, S. J.; Eom, K. Y.; Hwang, H.; An, D. K. Bull. Korean Chem. Soc.
2008, 29, 2303–2304; (c) Ha, J. H.; Ahn, J. H.; An, D. K. Bull. Korean Chem. Soc.
2006, 27, 121–122.
7. (a) Cha, J. S.; Yoon, M. S. Tetrahedron Lett. 1989, 30, 3677–3680; (b) Cha, J. S.;
Oh, S. Y.; Kim, J. E. Bull. Korean Chem. Soc. 1987, 8, 301–304.
8. Ferris, J. P.; Antonucci, F. R. J. Am. Chem. Soc. 1972, 1971, 1294–1295. and Chem.
Commun. 1971, 1294–1295.
9. Xi, F.; Kamal, F.; Schenerman, M. A. Tetrahedron Lett. 2002, 43, 1395–1396.
10. Zajac, W. W., Jr; Siuda, J. F.; Nolan, M. J.; Santosusso, T. M. J. Org. Chem. 1971, 36,
3539–3541.
11. Backeberg, O. G.; Staskun, B. J. Chem. Soc. 1962, 3961–3963.
12. Bodnar, Z.; Mallat, T.; Petro, J. J. Mol. Catal. 1991, 70, 53–64.
13. Chatterjee, A.; Shaikh, R. A.; Anuj Raj; Singh, A. P. Catal. Lett. 1995, 31, 301–305.
14. Larson, G. L.; Fry, J. L. In Ionic and Organometallic-Catalyzed Organosilane
Reductions; John Wiley & Sons, Inc., 2010. by Organic Reactions.
24. Pehlivan, L.; Métay, E.; Laval, S.; Dayoub, W.; Delbrayelle, D.; Mignani, G.;
Lemaire, M. Eur. J. Org. Chem. 2011, 7400–7406.
25. General procedure for the reduction of nitriles into aldehydes: 40-Methyl-2-
biphenylcarbonitrile 1d (Table 2 entry 4). To a nitrogen purged screw-caped
vial containing 1d (630 mg, 3.3 mmol, 1.0 equiv) in 500
lL of toluene were
added TMDS (5.8 mL, 32.8 mmol, 10.0 equiv) and V(O)(OiPr)3 (780
l
L,
3.3 mmol, 1.0 equiv) at rt. The mixture was then heated at 60 °C for 20 h
(the colorless solution turned into deep purple) and then cooled to room
temperature. The clear solution was diluted with toluene (10 mL) and acidified
using aqueous H3PO4 85% (2.0 g diluted in 5.0 ml of water, 5.2 equiv). The
organic layer was separated, washed with aqueous 1 m HCl (3 ꢀ 10 mL), dried
over
MgSO4
and
concentrated
under
vacuum
(40-methyl-2-
biphenylcarboxaldehyde 2d was present in 70% estimated GC yield). Flash
column chromatography on silica gel (cyclohexane/ethyl acetate 9:1) afforded
2d in 60% isolated yield. 1H NMR (300 MHz, CDCl3), d 2.43 (s, 3H, CH3), 7.28 (m,
4H, CH3-CHAr), 7.43 (dd, 1H, J = 7.7 and 0.8 Hz, CHO-CHAr), 7.48 (t, 1H,
J = 7.6 Hz, CHAr), 7.63 (td, 1H, J = 7.4 and 1.4 Hz, CHAr), 8.02 (dd, 1H, J = 7.6 and
1.1 Hz, CHAr), 9.99 (d, 1H, J = 0.8 Hz, CHO). 13C NMR (100 MHz, CDCl3) d 21.5,
127.7, 129.4, 130.1, 131.2, 133.5 (Cq), 133.9 (Cq), 135.1, 138.5 (Cq), 145.7 (Cq),
192.8 (CHO). GC–MS (EI, 70 eV) m/z = 196 [M+ꢁ], 195 [M+ꢁ–H], 181 [M+ꢁ–CH3],
167 (M+ꢁ–CHO), 152 [M+ꢁ-CHO–CH3].
26. Hirao, T. Pure Appl. Chem. 2005, 77, 1539–1557. and Coordination Chemistry
Reviews 2003, 237, 271–279 and Chem. Rev. 1997, 97, 2707–2722.
27. Petit, C.; Poli, E.; Favre-Réguillon, A.; Khrouz, L.; Denis-Quanquin, S.; Bonneviot,
L.; Mignani, G.; Lemaire, M. ACS Catal. 2013, 3, 1431–1438.