Fe-catalyzed synthesis of substituted N-aryl oxazolidines

Article abstract of DOI:10.1039/c6ob00185h

A novel iron-catalyzed synthesis of substituted N-aryl oxazolidines was developed via C-N bond formation and methylenation. The reaction of aryl hydroxylamines with allyl alcohols, in the presence of formaldehyde or its equivalents, afforded variety of oxazolidine heterocycles in very good yields. This catalytic method is most effective for para-substituted aryl hydroxylamines and 3-methyl allyl alcohols. Furthermore, acid catalyzed demethylenation of oxazolidines allowed access to N-aryl amino alcohols in good yields.

Full text of DOI:10.1039/c6ob00185h

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TOC Graphical abstract:
O
anh. FeCl
Para-
1.
2
N
formaldehyde
R
NHOH
R
+
OH
anh. FeCl
Para-
1.
2
OH
NH
formaldehyde
R
2. HCl
An unprecedented Fe-catalyzed oxazolidine formation was observed from the reaction of
allyl alcohols with arylhydroxylamines in presence of formaldehyde or its equivalents.

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Fe-Catalyzed Synthesis of Substituted N-Aryl Oxazolidines
Siva Murru, Charles Seth Lott, Brandon McGough, Dakota M. Bernard and Radhey S.
Srivastava*
Department of Chemistry, University of Louisiana at Lafayette, Lafayette, LA 70504.
rss1805@louisiana.edu
Abstract
O
N
anh. FeCl
Para-
1.
2
R
formaldehyde
NHOH
(Yield: 64-83%)
R
+
OH
anh. FeCl
Para-
1.
2
OH
NH
formaldehyde
2. HCl
R
(Yield: 58-73%)
A novel iron-catalyzed synthesis of substituted N-aryl oxazolidines was developed via C-N
bond formation and methylenation. The reaction of aryl hydroxylamines with allyl alcohols,
in the presence of formaldehyde or its equivalents, afforded variety of oxazolidine
heterocycles in very good yields. This catalytic method is most effective for para-substituted
aryl hydroxylamines and 3-methyl allyl alcohols. Furthermore, acid catalyzed
demethylenation of oxazolidines allowed access to N-aryl amino alcohols in good yields.
Introduction
Organonitrogen compounds and nitrogen heterocycles are prevalent in natural products and
biologically active molecules. Among them, oxazolidines have been utilized in organic
synthesis as synthetic intermediates,1 protecting groups,2 and as ligands for metal catalysis.3
Oxazolidines appear in numerous medicinally active compounds and natural products of
biological significance,4 such as quinocarcin.4e Similarly, N-arylated oxazolidines and
oxazolidinones are found to have antibiotic activity5 such as Linezolid (Zyvox),5a DuP105,5b
DuP721.5c A review of the literature reveals that a number of classical methods exist for
preparation of oxazoline, oxazolidine and oxazolidinone derivatives, utilizing N-
monosubstituted 1,2-amino alcohols as starting materials.6 However, it is difficult to prepare
N-monosubstituted 1,2-amino alcohols (β-amino alcohols) via N-arylation (or alkylation)
because of possible multi-substitutions. In applications such as medicine, materials, and total
synthesis, β-amino alcohols play a pivotal role as a building unit.7 Given their importance,
1

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developing a direct C–H amination8 towards synthesis of monosubstituted 1,2-amino alcohols
is highly attractive.
Results and Discussion
We envisioned that the C-H amination of allyl alcohols using substituted hydroxylamines as
nitrogen-donors would serve as an alternate method to afford the N-monosubstituted amino
alcohols. Accordingly, we have attempted to synthesize N-aryl amino alcohols starting from
allyl alcohols and N-aryl hydroxylamines using our previously developed amination
catalysts.9 However, Fe-catalyzed reaction of 2-methyl-2-butenol with phenyl hydroxylamine
in THF solvent didn’t produce any product. Surprisingly, the same reaction performed in p-
dioxane solvent yielded a product with higher mass (M+12) than the expected allyl amino
alcohol. Spectroscopic analysis revealed the product to be 3-phenyl-4-propenyl-1,3-
oxazolidine. (Scheme 1)
OH
NH
(1a')
FeCl2.4H2O
NHOH
+
OH
Dioxane, 60 o
C
O
(1)
(a)
N
(1a)
Scheme 1. Reaction of 3-methyl-2-butenol with phenyl hydroxylamine
The importance of the oxazolidine moiety, and serendipitous nature of the current reaction,
led us to consider exploring the reaction further in order to develop a general synthetic
method for N-arylated oxazolidines. We had initially focused on identifying the methylene
group (-CH2-) source by performing several control experiments. Thus we varied p-dioxane
with other solvents as shown in Table 1. Incidentally none of these produced the oxazolidine
(1a) or the amino alcohol (1a’), except for dichloromethane which produced oxazolidine (24
%). The oxazolidine formation could be due to the possible double nucleophilic substitution
on dichloromethane. This observation led us to explore the possible impurities present in p-
dioxane solvent.
Table 1. Screening of solvents for the reaction of 3-methyl-2-butenol with phenyl
hydroxylamine
NHOH
O
FeCl2.4H2O
OH
N
+
OH
NH
+
Solvent
(1)
(a)
(1a')
(1a)
2

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1a (%)a,b
Entry
1a' (%)a,b
Solvent
1
2
p-Dioxane
CH2Cl2
65
24
0
0
3
4
5
ClCH2CH2Cl
THF
0
0
0
0
Toluene
trace
trace
6
7
DMF
0
trace
MeOH
CHCl3
trace
trace
0
0
8
--------------------------------------------------------------------------------------
aGC yields; bRemaining substrate converts to azo and azoxy benzenes.
The commission on electroanalytical chemistry from IUPAC10 reports that reagent grade
dioxane obtained from different suppliers generally conform to ACS specifications11 which
includes water (~0.05%) and carbonyls (as HCHO, ~0.01%). Accordingly, we suspected that
the ‘methylene group’ might be from the formaldehyde impurity present in p-dioxane
solvent. In order to confirm our hypothesis, we performed a series of control experiments in
THF solvent with a variety of formaldehyde equivalents (methylene donors) including para-
formaldehyde, 1,3,5-trioxane, 1,1’-dimethoxymethane, and aqueous formaldehyde. (Table 2)
Here we have observed the formation of oxazolidine product in all cases, which indicates the
significance of formaldehyde (or its equivalents) in producing oxazolidine. Interestingly,
these screening experiments reveal that the C-N bond formation (allylic amination) occurs
only in presence of methylene (‘CH2’) donors. Thus, it is evident that both allylic amination
Table 2. Screening of formaldehyde and it’s equivalents for the reaction of 3-methyl-2-
butenol with phenyl hydroxylamine
--------------------------------------------------------------------------------------------------------
aGC yields; bRemaining substrate converts to azo and azoxy benzenes;
cInconsistent results were obtained when we used p-dioxane from different suppliers.
3

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and methylenation occurs simultaneously and are synergistic. Though the paraformaldehyde-
THF (entry 2, table 2) and p-dioxane (entry 5, table 2) are equally effective, the experimental
results with p-dioxane vary considerably when it is used from different suppliers. Hence we
chose para-formaldehyde/THF combination for the catalysts screening.
Among the various known allylic amination catalysts tested, FeCl3.6H2O, FeCl2.4H2O, anh.
FeCl3 and anh. FeCl2 were found to be effective and afforded oxazolidine product in 56%,
68%, 78% and 84% respectively (entries 1-4, Table 3) which shows the unique catalytic
activity of Fe-chloride catalysts towards oxazolidine formation. Further experimentation
suggested the optimum ratios of hydroxylamine:allyl alcohol:Fe-catalyst to be 1:3:0.1.
Though the reactions were faster at higher temperature, we maintained a uniform temperature
of 60 oC for all the reactions in order to avoid the formation of side products such as azo and
azoxy arenes.
Table 3. Screening of allylic amination catalysts for the reaction of 3-methyl-2-butenol with
phenyl hydroxylamine
[M]-catalyst
NHOH
O
N
OH
+
Para-
formaldehyde
(1a)
(a)
(1)
THF
Oxazolidine (%)a,b
Entry
Catalyst
FeCl2.4H2O
anh. FeCl2
anh. FeCl3
1
2
3
4
68
84
78
FeCl3.6H2O
Fe(Pc)
56
9
5
CuCl2
6
7
trace
CuCl
0
CuBr
8
0
Co(Pc)
anh. Mn(OAc)2
9
trace
0
10
---------------------------------------------------------------------------------------
aGC yields; bRemaining substrate converts to azo and azoxy benzenes.
Having optimized the reaction conditions, we next evaluated the scope of the reaction using
substituted aryl hydroxylamines (a-j) with 3-methyl-2-butenol (1). In general, the reactions
were very clean, and the 3-aryl-4-propenyl-oxazolidine compounds were obtained in high
yields under the optimized reaction conditions. As far as the oxazolidine formation is
concerned, all hydroxylamines are equally effective except ortho-substituted aryl
hydroxylamines (j and k). Several substituents and functional groups such as methyl (1b),
4

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halogens (1c, 1d, 1e and 1f), nitrile (1g), ester (1h) and amide (1i) were compatible for the
current reaction. It should be noted here that the halogen substituted oxazolidine compounds
(1c, 1d and 1e) allow further elaboration on the synthesis of complex compounds via metal
catalyzed coupling reactions.12 On the other hand, o-Tolyl hydroxylamine (j) is not effective
under optimized reaction conditions which might be due to steric hinderance.
Table 4. Reaction of allyl and homoallyl alcohols with aryl hydroxylamines a,b
10 mol% anh.
R
FeCl2
NHOH
R
O
OH
+ R'
N
R
OH
+
NH
1.2 equiv. para-
formaldehyde
anh. THF, 60 o
(1-4)
(a-l)
C
R'
R'
O
O
O
N
N
N
(1c, 71%)
(1b, 73%)
(1a, 78%)
Cl
Me
O
O
O
N
(1f, 68%)
N
N
(1d, 76%)
(1e, 83%)
Cl
Cl
Br
I
O
O
O
N
(1h, 75%)
N
N
(1g, 72%)
(1i, 66%)
BnHN
NC
EtO
O
O
OH
O
O
NH
N
N
(1k, 64%)c
(1j, trace)
(1l, 74%)
I
Me
I
O
N
(2a, 69%)
----------------------------------------------------------------------------------------------------------------
aisolated yields; bassociated with <5% of azo and azoxy benzenes; ca small amount (<10%) of oxazolidine was
observed.
In order to test our hypothesis, we tested the reaction with 2-Iodo phenylhydroxylamine (k)
where the direct formation of allyl amino alcohol (1k) as major product was observed. The
difference in reactivity of 4-Iodo and 2-Iodo phenylhydroxylamines (e and k) could possibly
be due to steric effects of ortho substitution. Later we also treated 3-Iodo
5

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phenylhydroxylamine (l) with allyl alcohol (1) under the same reaction conditions.
Surprisingly, 3-Iodo phenylhydroxylamine (l) did produce oxazolidine (1l) in very good
yield. Thus from the present study, we found the following order of substituted aryl
hydroxylamines’ reactivity in making oxazolidines: para > meta > ortho. Success of this
strategy was applied to other allyl and homo-allyl alcohols. We chose Geraniol (2), which is a
monoterpenoid and an alcohol, as an allyl alcohol counterpart that afforded 2a in 69% yield
(table 4) and the excess Geraniol was recovered after column chromatography. Interestingly,
a chemoselective reaction occurred in which only the allyl alcohol group was involved, but
not the other allyl moiety. As expected, 2-methyl-2-propenol (3) produced the corresponding
1,3-amino alcohol (3a) in 21% yield. On the other hand, 3-methyl-3-butenol (4) afforded
mixture of isomeric 1,4-amino alcohols (4a and 4a’) in 28% yield. (Scheme 2) However we
did not observe any 6- or 7-membered N,O-heterocycles which might be due to the C-N bond
formation at C-3 and C-4 positions, instead of C-2 position.
OH
PhNHOH
OH
OH
NH (3a)
Ph
10 mol% anh.
FeCl2
1.2 equiv. para-
formaldehyde
anh. THF, 60 o
C
OH
+
OH
NH
(4a')
(4a)
NH
Ph
Ph
Scheme 2. Reaction of 2-methyl-2-propenol and 3-methyl-3-butenol with phenyl
hydroxylamine
Our aforementioned goal was to develop a synthetic method to access N-aryl amino alcohols.
Keeping that in mind, we investigated the demethylenation of the oxazolidine compounds in
order to obtain allyl amino alcohols. Allyl amino alcohols are reported previously13 via
oxidative amination of allyl alcohols but they are not efficient probably because of the
interference by the alcohol (-OH) group. In order to obtain the targeted amino alcohols as end
products, we extended the method via demethylenation of oxazolidine products by acid
treatment. In a typical experiment, 3-methyl-2-butenol (1) was treated with phenyl
o
hydroxylamine (a) in THF using anh. FeCl2 as a catalyst at 60 C. After 5 hours, the solvent
was removed and treated directly with conc. HCl to obtain allyl amino alcohol (1a’) as shown
in Table 5. This seems to be a promising approach for allyl amino alcohols synthesis. Amino
alcohols 1c’ and 2a’ were obtained in good yields starting from the corresponding allyl
alcohols and aryl hydroxylamines (Table 5).
6

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Table 5. Synthesis of allyl amino alcohols via amination and methylene bridge formation a,b
1. anh. FeCl2
(0.05 mmol )
Para-formaldehyde
OH
(0.6 mmol)
(1)
+
ArNHOH
THF, 60 o
C
OH
NH
2. Conc. HCl
Ar
OH
OH
NH
OH
NH
NH
(1c', 66%)
(1a', 73%)
(1d', 69%)
Cl
Br
OH
NH
(2a', 58%)
aisolated yields; bassociated with <5% of azo and azoxy benzenes.
Having studied the synthesis of N-aryl oxazolidines and N-aryl amino alcohols, we observed
that the C-N bond formation occur only in presence of paraformaldehyde or its equivalents.
As we previously established, the amination reaction (C-N bond formation) involves the
formation of activated nitroso-intermediates that are highly electrophilic in general.9a,b
Consequently the allyl alcohols (-OH groups), which are nucleophilic in nature, could be
detrimental to the amination reaction (C-N bond formation) via possible unwanted reaction
with electrophilic nitroso compounds. However the presence of formaldehyde (or its
equivalents) possibly serves as an acetal protecting group for the vulnerable alcohol (-OH)
group that facilitates the new C-N bond formation via allylic C-H amination. Subsequent
intramolecular nucleophilic substitution affords oxazolidines as end products along with
regeneration of one equivalent of the allyl alcohol. (Scheme 3)
O
[Fe]-Cat
2
+
OH
O
- H2O
H
O
H
[methylene acetal]
[Fe]-Cat
- H2O
ArNHOH
+
O
O
HO
O
N
Ar
NH
Ar
Scheme 3. Plausible reaction pathway for the N-aryl oxazolidine formation.
7

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Conclusion
We have demonstrated that 3-aryl-4-propenyl oxazolidines can be obtained from the
corresponding allyl alcohols and aryl hydroxylamines in moderate to excellent yields. anh.
FeCl2 was found to be the most efficient catalyst for the synthesis of oxazolidines via C-N
bond and methylene bridge formation. Para substituted aryl hydroxylamines favor
oxazolidine formation compared to the ortho-substitution because of possible steric effects.
Interestingly, Geraniol was involved in a chemo-selective reaction which afforded the
corresponding oxazolidine in good yield. We have also established that the method can be
extended to make allyl amino alcohols via acid catalyzed demethylenation. Further scope and
asymmetric applications of the process are currently ongoing in our laboratory.
Experimental Procedures
General Procedure for the Preparation of 4-Propenyl-3-Aryl Oxazolidines: To the
solution of anh. FeCl2 (0.05 mmol), allyl alcohol (1.5 mmol) and para-formaldehyde (0.6
mmol) in anh. THF (5 mL), the aryl hydroxylamine (0.5 mmol) solution was added slowly in
o
THF (5 mL) using a syringe pump over 4 hours at 60 C while keeping the flask under inert
atmosphere using nitrogen balloon. Reactions were allowed to continue for two more hours
for the complete consumption of aryl hydroxylamine. Then the mixture was filtered through
celite and the filtrate was concentrated to dryness. The crude product was purified over a
short column of silica gel (hexane/ethyl acetate eluents) to obtain the pure oxazolidine which
was then directly analyzed by GC-MS, NMR, ESI-MS and FT-IR.
General Procedure for the Synthesis of Allyl Amino Alcohols: To the propenyl
oxazolidine (obtained from the previous step) in a RB flask, 2 mL of conc. HCl was added
and stirred for 2 hours. Once the reaction is completed (monitored by TLC and GC-MS), the
mixture was filtered through celite and the filtrate was concentrated to dryness. The crude
product was purified over a short column of silica gel (hexane/ethyl acetate eluents) and the
isolated pure N-aryl amino alcohol which was then confirmed the structure by GC-MS,
NMR, FT-IR and HR-MS analysis.
Acknowledgments
We are thankful to the NMR Facility at Louisiana State University, Baton Rouge for
providing the NMR data. Thanks are also due to Louisiana Board of Regents for the financial
support [LEQSF(2013-16)-RD-B-06].
References
1. (a) P. Wipf and S. Venkatraman, J. Org. Chem., 1995, 60, 7224; (b) M. Ousmer, N. A.
Braun and M. A. Ciufolini, Org. Lett., 2001, 5, 765; (c) J. T. Yli-Kauhaluoma, C. W.
8

Organic & Biomolecular Chemistry
Page 10 of 11
View Article Online
DOI: 10.1039/C6OB00185H
Harwig, Jr., P. Wentworth and K. D. Janda, Tetrahedron Lett., 1998, 39, 2269; (d) B.
Wang, E. H. M. Elageed, D. Zhang, S. Yang, S. Wu, G. Zhang and G. Ga,
ChemCatChem, 2014, 6, 278.
2. T. W. Green and P. G. M. Wutz, Protecting Groups in Organic Synthesis, 2nd ed.; John
Wiley and Sons: New York, 1991.
3. (a) F. Fache, E. Schulz, M. L. Tommasino and M. Lemaire, Chem. Rev. 2000, 100, 2159;
(b) K. A. Jørgensen, M. Johannsen, S. Yao, H. Audrain and J. Thurhauge, Acc. Chem.
Res., 1999, 32, 605; (c) H. A. McManus and P. J. Guiry, Chem. Rev., 2004, 104, 4151;
(d) C. H. Senanayake, D. Krishnamurthy, I. Gallou, In Handbook of Chiral Fine
Chemicals; Ager, D., Ed.; Taylor&Francis Ed.: New York, 2005; p 117, 319, 457; (e) R.
Almansa, D. Guijarro and M. Yus, Tetrahedron: Asymmetry 2007, 18, 896.
4. (a) P. Wipf, P. C. Fritch, S. J. Geib and A. M. Sefler, J. Am. Chem. Soc., 1998, 120, 4105;
(b) S. Deng and J. Taunton, J. Am. Chem. Soc., 2002, 124, 916; (c) S.-L. You and J. W.
Kelly, Chem. Eur. J. 2004, 10, 71. (d) Y. Momose, T. Maekawa, T. Yamano, M. Kawada,
H. Odaka, H. Ikeda and T. Sohda, J. Med. Chem., 2002, 45, 1518; (e) R. M. Williams, T.
Glinka, M. E. Flanagan, R. Gallegos, H. Coffman and D. Pei, J. Am. Chem. Soc., 1992,
114, 733.
5. (a) T. A. Mukhtar and G. D. Wright, Chem. Rev. 2005, 105, 529; (b) W. A. Gregory, D.
R. Brittelli, C. L. J. Wang, M. A. Wuonola, R. J. McRipley, D. C. Eustice, V. S. Eberly,
A. M. Slee, M. Forbes and P. T. Bartholomew, J. Med. Chem. 1989, 32, 1673; (c) M. R.
Barbachyn, D. K. Hutchinson, S. J. Brickner, M. H. Cynamon, J. O. Kilburn, S. P.
Klemens, S. E. Glickman, K. C. Grega, S. K. Hendges, D. S. Toops, C. W. Ford and G. E.
Zurenko, J. Med. Chem. 1996, 39, 680.
6. (a) B. Eftekhari-Sis, M. Zirak and A. Akbari, Chem. Rev., 2013, 113, 2958 and references
cited therein; (b) C. Hajji, E. Z. Garcia and J. Sepulveda-Arques, Syn. Commun., 2010,
33, 4347; (c) G. Choi and T. Tatewaki, “Jpn Kokai Tokyo Koho” Japanese Patent No. Jp.
2010024286, 2010; (d) M. Al-Masum, B. W. Lott and N. Ghazialsharif, Int. J. Org.
Chem. 2012, 2, 362; (e) J.-G. Shim, Y. Yamamoto, Heterocycles 2000, 52, 885; (f) J.-G.
Shim and Y. Yamamoto, Tetrahedron Lett. 1999, 40, 1053; (g) M. B. Shaghafi, R. E.
Grote and E. R. Jarvo, Org. Lett., 2011, 13, 5188; (h) A. F. Ward, J. P. Wolfe, Org. Lett.
2011, 13, 4728. (i) S. Gandhi, A. Bisai, B. A. Prasad and V. K. Singh, J. Org. Chem.
2007, 72, 2133. (j) D. J. Michaelis, M. A. Ischay, T. P. Yoon, J. Am. Chem. Soc. 2008,
130, 6610; (k) P. Chaudhry, F. Schoenen, B. Neuenswander, G. H. Lushington and J.
Aube, J. Comb. Chem., 2007, 9, 473.
9

Page 11 of 11
Organic & Biomolecular Chemistry
View Article Online
DOI: 10.1039/C6OB00185H
7. (a) S. C. Bergmeier, Tetrahedron, 2000, 56, 2561; (b) D. J. Ager, I. Prakash and D. R.
Schaad, Chem. Rev., 1996, 96, 835; (c) O. K. Karjalainen and A. M. P. Koskinen, Org.
Biomol. Chem., 2012, 10, 4311.
8. (a) F. Collet, R. H. Dodd and P. Dauban, Chem. Commun. 2009, 5061; (b) F. Collet, C.
Lescot and P. Dauban, 2011, 40, 1926; (c) J. L. Jeffrey and R. Sarpong, Chem. Sci., 2013,
4, 4092; (d) T. A. Ramirez, B. Zhao and Y. Shi, Chem. Soc. Rev., 2012, 41, 931.
9. (a) R. S. Srivastava, M. A. Khan and K. M. Nicholas, J. Am. Chem. Soc. 2005, 127, 7278;
(b) R. S. Srivastava, N. R. Tarver and K. M. Nicholas, J. Am. Chem. Soc. 2007, 129,
15250; (c) R. S. Srivastava, R. BertrandIII and K.M. Nicholas, Tetrahedron Lett. 2011, 52,
3478; (d) S. Murru, A. A. Gallo and R. S. Srivastava, ACS Catal. 2011, 1, 29; (e) S.
Murru, A. A. Gallo and R. S. Srivastava, J. Org. Chem. 2012, 77, 7119; (f) S. Murru and
R. S. Srivastava, Eur. J. Org. Chem. 2014, 10, 2174; (g) S. Murru, B. McGough and R. S.
Srivastava, Org. Biomol. Chem. 2014, 12, 9133. (h) S. Murru, C. S. Lott and R. S.
Srivastava, Org. Lett., 2015, 17, 2122.
10. J. F. Coetze and T.-H. Chang, Pure Appl. Chem. 1985, 57, 63.
11. "Reagent Chemicals", American Chemical Society, Washington, D.C., 5th edition, 1974,
p. 237-239.
12. (a) “Cross Coupling Reactions: A Practical Guide” Edited by N. Miyaura. Topics in
Current Chemistry, Vol. 219. Springer-Verlag: Heidelberg. 2002; (b) F. Bellina and R.
Rossi, Chem. Rev. 2010, 110, 1082; (c) J. Bariwal and E. V. Eycken, Chem. Soc. Rev.
2013, 42, 9283.
13. (a) S. Singh and K. M. Nicholas, Syn. Commun. 2001, 31, 3087; (b) R. S. Srivastava and
K. M. Nicholas, Chem. Commun. 1996, 20, 2335.
10