Kinetic and mechanistic insight into Lewis base and acid-mediated phenylselenoetherification of 2,6-dimethyl-hept-5-en-2-ol

Article abstract of DOI:10.1007/s11224-015-0570-3

Abstract Mechanistic and kinetic aspects, as well as quantum chemical calculations, for the formation of a tetrahydrofurane ring by cyclization of the highly substituted alcohol-2,6-dimethyl-hept-5-en-2-ol with phenylselenohalides (PhSeCl and PhSeBr), in

Full text of DOI:10.1007/s11224-015-0570-3

Struct Chem
DOI 10.1007/s11224-015-0570-3
ORIGINAL RESEARCH
Kinetic and mechanistic insight into Lewis base and acid-mediated
phenylselenoetherification of 2,6-dimethyl-hept-5-en-2-ol
•
Marina D. Kostic Vera M. Divac
•
´
Ralph Puchta Zorica M. Bugarcic
•
ˇ ´
Received: 28 November 2014 / Accepted: 30 January 2015
Ó Springer Science+Business Media New York 2015
Abstract Mechanistic and kinetic aspects, as well as
quantum chemical calculations, for the formation of a
tetrahydrofurane ring by cyclization of the highly substi-
tuted alcohol–2,6-dimethyl-hept-5-en-2-ol with phenylse-
lenohalides (PhSeCl and PhSeBr), in the presence of
various Lewis bases (piperidine, triethylamine, pyridine and
quinoline) and Lewis acids (CoCl2, SnCl2) as additives
were studied. The substituted tetrahydrofuran ring is com-
mon motif in many natural products, especially in bioactive
marine macrolides. Due to the presence of additives in
reactions, the high regioselectivity was achieved, and the
tetrahydrofuran type of ether in all studied reactions was
obtained in excess in regard to the six-membered cyclic
ether. In addition, kinetic aspects of reactions mediated by
Lewis bases were studied by UV–Vis spectroscopy (in
THF, at 288 K), as reactions of pseudo-first-order. Obtained
values for rate constants proved catalytic role of additives
and indicated that the reaction rate depends on pKa values
of used base as well as on their ability for formation of
hydrogen bond with OH–alcohols group.
Keywords Kinetics ꢀ Cyclization ꢀ Transition state
structure ꢀ Quantum calculations
Introduction
Substituted oxygen heterocycles, particularly five- and six-
membered cyclic ethers, have attracted special attention in
recent years due to their occurrence as structural units of many
bioactive natural products, such as polyether antibiotics,
acetogenins and C-glycosides [1–4]. Thus, the development
of methods that enable access to their effective construction is
of significant importance, and many strategies have been ex-
plored for this purpose [5–9]. It is now well established that
selenium-induced cyclofunctionalization of unsaturated
alcohols represents an easy access to a wide variety of hete-
rocyclic compounds containing oxygen atom [10, 11]. This
syntheticmethodhastheadvantagethattheintroductionofthe
heteroatom, the manipulation of the obtained product and the
removal of the function from the side chain is facilitated by
simple and mild experimental conditions.
Electronic supplementary material The online version of this
article (doi:10.1007/s11224-015-0570-3) contains supplementary
material, which is available to authorized users.
´
In memoriam to Prof. Dr. Dr. h.c. mult. Paul von Rague Schleyer
(February 27 1930–November 21 2014) sc
´
ˇ ´
M. D. Kostic (&) ꢀ V. M. Divac ꢀ Z. M. Bugarcic
Department of Chemistry, Faculty of Science, University of
´
Kragujevac, Radoja Domanovica 12, P.O. Box 60,
34 000 Kragujevac, Serbia
e-mail: mrvovic@kg.ac.rs
As a part of our ongoing research, directed toward the
intramolecular cyclization of unsaturated alcohols by
means of phenylselenenyl halides as reagents, we have
examined the chemo-, regio-, stereoselectivity and reaction
kinetics as a function of substitution pattern at the double
bond and at the carbinol carbon atom of the used alkenol
substrate. The influence of some Lewis acids and bases as
catalysts on mechanistic pathway and reaction rate has also
been evaluated [12–21].
R. Puchta
Institute for Inorganic Chemistry, Department of Chemistry and
Pharmacy, University of Erlangen-Nu¨rnberg, Egerlandstrasse 1,
91058 Erlangen, Germany
R. Puchta
Computer Chemistry Center, Department of Chemistry and
¨
Pharmacy, University of Erlangen-Nu¨rnberg, Nagelsbachstrasse
25, 91052 Erlangen, Germany
123

Struct Chem
The present paper deals with synthetic, mechanistic and
kinetic aspects of the reaction between the tertiary alkenol
(2,6-dimethyl-hept-5-en-2-ol) which has a highly substi-
tuted double bond and the phenylselenyl halides (PhSeBr
and PhSeCl), in the presence of some Lewis bases and
acids as additives (piperidine, pyridine, quinoline, triethy-
lamin, CoCl2 and SnCl2).
stepped process. The first phase of the reaction involves the
electrophilic attack of the phenylselenenyl group on the
double bond of the alkenol, which results in the formation
of a seleniranium ion I. In the next phase of the reaction,
the nucleophilic attack of the hydroxyl oxygen occurs,
which result in the formation of the oxonium ions Ia and
Ib. Finally, the formation of the five- and six-membered
cyclic ethers, 1a and/or 1b, occurs with the elimination of
the protons from the oxonium ions. The presence of the
nucleophilic halide anion is sometimes responsible for
some undesirable processes such as its attack on the
selenonium ion and the formation of the side product 1c,
which causes a lower yield of the cyclic ether products.
In order to decrease the side reactions and to increase
the yields of cyclic products, we performed experiments
with two different sets of additives: some Lewis acids
(SnCl2, CoCl2) and some Lewis bases/Brønsted bases
(piperidine, triethylamine, pyridine and quinoline). The
obtained results are presented in Table 1. The use of
equimolar amounts of Lewis/Brønsted bases and acids as
additives led to almost quantitative yields of the cyclic
ethers, even in the case of PhSeBr as the reagent. The
distribution of products proceeds with higher regioselec-
tivity than in the case of reactions without present additive.
In all investigated reactions, tetrahydrofuran type of ether
was obtained in excess. The best results in terms of
regioselectivity were achieved with SnCl2 as the catalyst.
The role of Lewis acids in these reactions is to increase the
electrophilicity of the reagent (PhSeX) and to decrease a
possibility of halide addition by removing the anion from
the reagent and in that way to improve the yields of the
desired cyclic products.
Result and discussion
Cyclofunctionalization of D4- and D5-unsaturated alkenols,
by means of PhSeX (X = Cl, Br) as reagents, occurs
through the formation of a seleniranium ion and the sub-
sequent attack of the OH group. Depending on the reaction
conditions, the formation of seleniranium ion can be
reversible process and at low temperatures usually under
kinetic control [10, 22]. While the selenocyclofunctional-
ization of primary and secondary alkenols is usually driven
by electronic factors, and formation of corresponding five-
or six- membered rings occurs in Markovnikov fashion
(regioselectivity), the effect of steric hindrances is decisive
in the course of tertiary alkenol transformation, where the
product of anti-Markovnikov’s rule can be expected. Sub-
stituents at the carbinol carbon atom display strong influ-
ence on the decrease in yields of cyclic ether products.
Therefore, transformation of primary alkenols proceeds in
moderate to good yields, secondary alkenols cyclizate in
considerable lower extent, while tertiary alkenols do not
undergo cyclization with PhSeBr, and in small yields with
PhSeCl as a reagent.
Cyclofunctionalization of 2,6-dimethyl-hept-5-en-2-ol 1
with PhSeX (X = Cl, Br) can afford two structural isomers
(substituted tetrahydrofuran 1a or tetrahydropyran 1b type
of cyclic ethers), through exo- and endo-cyclization path-
way (Scheme 1). A previous study has shown that its
secondary analog (6-methyl-hept-5-en-2-ol 2) at -78, 0 °C
and room temperature gave only the six-membered cyclic
ether 2b as a result of Markovnikov’s orientation, regard-
less of the employed cyclization reagent. An increase of
only one methyl group at the carbinol carbon atom in our
substrate 1, in regard to its secondary analog, leads to the
steric control of the reaction and predominantly formation
of five-membered ring 1a by exo-cyclization pathway at
-78 and 0 °C, while at room temperature, the six-mem-
bered ring 1b was obtained as main reaction product
(Scheme 1) [23]. This is another validation of the very
delicate relationship between electronic and steric contri-
butions on the final outcome of the reaction. No cyclization
products were observed in the case of 1 when the PhSeBr
was used as reagent.
The merit for the increased yields in the reactions with
bases can be ascribed to the ability of the Brønsted bases to
form hydrogen bonds with the substrate’s OH group,
facilitating the formation of the cyclic ether. The rapid
abstraction of a proton stabilizes the intermediate directs its
transformation to the product [18]. Since there are
increased steric demands for the OH nucleophilic approach
due to hydrogen bonded base, the formation of the main
reaction product is determined by the OH attack on the
sterically less hindered C-5 carbon as shown in Fig. 1 (anti-
Markovnikov orientation).
To get an impression of the influence of the steric effects
of the applied base in comparison with the consequences of
CH3 groups neighboring to the two reactive motifs, the OH
group and the double bond, we performed quantum chemical
calculations. As we investigated the possible reaction path-
ways already before [18, 19], we focused here on a com-
parison of the transition states leading to the five- and six-
membered ether applying the smallest possible base NH3 as
in our earlier studies [18, 19]. As alkenoles, we utilized of
course 2,6-dimethyl-hept-5-en-2-ol and 6-methyl-hept-5-
Scheme 2 describes the mechanism of the phenylsele-
noetherification of 2,6-dimethyl-hept-5-en-2-ol as a two-
123

Struct Chem
SePh
R
R
PhSeX (X = Cl, Br)
R
+
OH
O
SePh
O
1a
2a
1b
2b
endo-
1
2
R=CH3
R=H
exo-
Reagent
PhSeCl
Substrate
-78°C
0 °C
r.t
1a
2b
75 % (95:5)
90 % (0:100)
45 % (66:34)
73 % (0:100)
37 % (31:69)
68 % (0:100)
1a
2b
/
/
/
PhSeBr
30 % (0:100)
22 %(0:100)
18 % (0:100)
a - ratio in parentheses 1a:1b; b - ratio in parentheses 2a:2b
Scheme 1 Selenocyclofunctionalization of 2,6-dimethyl-hept-5-en-2-ol and 6-methyl-hept-5-en-2-ol
Ph
X
SePh
Se
PhSeX (X=Cl, Br)
k2
+
b
O
H
1
SePh
O
O
O
c
H
I
H
Ia
H
Ib
k1
- H
- H
X
OH
SePh
+
SePh
O
SePh
O
1a
1c
1b
Scheme 2 Mechanism of the phenylselenoetherification of 2,6-dimethyl-hept-5-en-2-ol
Table 1 Yields (%) and ratio (1a:1b) of cyclic ether products in the phenylselenoetherification of 2,6-dimethyl-hept-5-en-2-ol in the presence of
some Lewis bases and acids as additives
Without additive
Et3N
Pyridine
Quinoline
Piperidine
CoCl2
SnCl2
PhSeCl
PhSeBr
37
98
96
98
100
98
97
(69:31)
(86:14)
99
(95:5)
99
(84:16)
99
(96:4)
100
(96:4)
97
(100:0)
96
–
–
(96:4)
(86:14)
(96:4)
(97:3)
(95:5)
(100:0)
en-2-ol to get an impression of the influence of an extra
methyl group next to OH. For both alkenoles, the transition
state leading to the furanoide ether is significantly more
stable than the transition state leading to the pyranoide form,
independently if we compare B3LYP or MP2(fc) energies
(see Table 2; Figs. 2, 3) The extra methyl group in 2,6-
123

Struct Chem
sp2-C-atom, dedicated to form the new bond, in the fura-
noide transition states are consequently shorter (2,6-dime-
˚
thyl-hept-5-en-2-ol: 2.08 A, 6-methyl-hept-5-en-2-ol:
˚
2.04 A) than in the pyranoide’s form transition state (2,6-
˚
dimethyl-hept-5-en-2-ol: 2.16 A, 6-methyl-hept-5-en-2-ol:
˚
2.14 A).
H3C
H3C
Se
In order to compare the impact of the used base addi-
tives on the reaction pathway and rate constants, conven-
tional kinetic method by UV/Vis spectroscopy was used.
All reactions were studied as reactions of pseudo-first-order
at 288 K in THF as solvent. The attack on the selenonium
cation by the OH internal nucleophile was considered as
the rate determining step. Reactions were investigated by
following the dependence of the absorbance on reaction
time at suitable wavelength. The calculations for the kobsd
are explained in the ‘‘Experimental section’’ section and
the data are given in Tables 1S and 2S (Supplementary
material). The observed rate constants as a function of total
alcohol concentration can be described by the following
equation:
H
O
CH3
CH3
δ
H
B
δ
H
N
N
N
Et3N
B =
Fig. 1 Steric hindrance during the ring-closing phase in the reactions
facilitated by bases
kobsd ¼ k1 þ k2½alcoholꢁ
In this equation, k2 represents the second-order rate
constant for the forward reaction (cyclization reaction),
which depends on alcohol concentration, and k1 shows the
effects of the parallel reaction (reaction of addition). The
rate constant k1 is independent of the alcohol concentration.
The values of k2 were calculated from the slopes of
the plots kobsd versus the alcohol concentration, while the
values for k1 were determined from the intercept of the
observed lines. (Table 3; Fig. 4) [24].
dimethyl-hept-5-en-2-ol shows, compared to 6-methyl-hept-
5-en-2-ol, only an insignificant influence on the transition
state’s selectivity beyond the accuracy of the applied quan-
tum chemical methods.
Therefore, we calculated the possible five- and six-
membered cyclic phenylseleno ethers. In the case of the
cyclic systems derived from 2,6-dimethyl-hept-5-en-2-ol,
the resulting compound tetrahydro-2,2-dimethyl-5-(2-
(phenylselanyl)propan-2-yl)furan and tetrahydro-2,2,6,6-
tetramethyl-3-(phenylselanyl)-2H-pyran within the accura-
cy of the applied methods best addressed as energetic equal
(pyranoid forms a bit less stable MP2: ?1.3 kcal/mol
B3LYP: 0,1 kcal/mol). This is clearly different in the case of
6-methyl-hept-5-en-2-ol, here tetrahydro-2,2,6-trimethyl-3-
(phenylselanyl)-2H-pyran is around 5 kcal/mol more stable
(MP2: 4.2 kcal/mol, B3LYP: 5.6 kcal/mol) than tetrahydro-
2-methyl-5-(2-(phenylselanyl)propan-2-yl)furan.
From the results given in Table 3, it can be seen that in
the catalyzed reactions with PhSeCl as the reagent, the
values for the rate constants are from 2 to 6 orders of
magnitude higher than in the case of the uncatalyzed
reactions. Furthermore, the variation of used cyclization
reagent has significant influence on the reaction rate. The
values of the rate constants for the catalyzed reactions with
PhSeCl as the reagent are higher than for analogs reactions
with PhSeBr. Additionally, it was found that the efficiency
of the used catalysts is following the order: piperidine [
triethylamine [ pyridine [ quinoline, which corresponds
In accordance with earlier findings [18, 19], the distance
between the entering H3NꢀꢀꢀHO group and the formally
Table 2 Calculated energy differences of the two possible transition states
ts leading to the furanoide ether
ts leading to the pyranoide ether
2,6-dimethyl-hept-5-en-2-ol
6-methyl-hept-5-en-2-ol
0,0 kcal/mol (0,0 kcal/mol)
0,0 kcal/mol (0,0 kcal/mol)
?5,9 kcal/mol (?3.9 kcal/mol)
?6.1 kcal/mol (?3.7 kcal/mol)
MP2(fc)/6-311?G**//B3LYP/6-311?G** ? ZPE(B3LYP/6-311?G**)
Values in parentheses: B3LYP/6-311?G** ? ZPE(B3LYP/6-311?G**)
123

Struct Chem
Fig. 2 Calculated transition states for furanoid and pyranoid form for phenylselenoetherification of 6-methyl-hept-5-en-2-ol
to the pKa values of the used bases [25, 26]. The results
listed in Table 2 indicate that the nature of the used bases
has a strong impact on their catalytic activity. It is well
known that the ring-closing phase is highly sensitive on
increase of the steric hindrances and therefore can often
cause the change of the reaction pathway. Thus, despite the
highest ability of triethylamine for hydrogen bond forma-
tion (DN = 61) the opposite to piperidine’s (DN = 40), its
catalytic activity is relatively shrunk due to its greater
steric necessities.
Experimental section
General. Gas–liquid chromatography (GLC) analyses were
performed with a Deni instrument, model 2000 with cap-
illary apolar columns. 1H and 13C NMR spectra were run in
CDCl3 on a Varian Gemini 200 MHz NMR spectrometar.
IR spectra were obtained with Perkin-Elmer Model 137B
and Nicolet 7000 FT spectrophotometers. Thin-layer
chromatography (TLC) was carried out on 0.25 mm E.
Merck precoated silica gel plates (60F-254) using UV light
for visualization. For column chromatography, E. Merck
silica gel (60, particle size 0.063–0.200 mm) was used.
For the kinetic measurements, UV–Vis Perkin Elmer
Lambda 35 spectrophotometer equipped with a ther-
mostatted cell was used.
From the graphs in Fig. 3, it can be seen that the plots of
kobsd versus [alcohol] are linear. All graphs of catalyzed
reactions start from the origin, demonstrating the values for
the constants k1 are insignificantly small, which is in agree-
ment with the preparative results (no parallel reaction pre-
sent). In contrast, in the uncatalyzed reaction with PhSeCl, an
intercept occurs (value for k1 shown in Table 3). The plot of
General synthetic procedure
k
obsd versus [alcohol], with PhSeBr as a reagent, is not pre-
sented, because no cyclization products are observed under
these experimental conditions (Table 1).
All reactions were carried out on a 1 mmol scale. To a
magnetically stirred solution of the alkenol (1 mmol) and the
additive (1 mmol) in dry dichloromethane (5 cm3), solid
PhSeX (X = Cl or Br) (1.1 mmol) was added at room tem-
perature. The reaction went to completion in a few minutes.
The pale yellow solution was washed with 5 ml of 1 M HCl
The linear relationship in the Brønsted plot of log k2
versus pKa indicates that all used catalysts, despite their
structural differences, increase the reaction rates if the
same reaction mechanisms are traversed (Fig. 5).
123

Struct Chem
Fig. 3 Calculated transition states for furanoid and pyranoid form for phenylselenoetherification of 2,6-dimethyl-hept-5-en-2-ol
Table 3 Rate constants for phenylselenoetherification of 2,6-dimethyl-hept-5-en-2-ol in THF at 288 K
PhSeCl
pKa
PhSeBr
k2 (M-1 -1
k2 (M-1 -1
s
)
k1 (s-1
)
s
)
k1 (s-1
)
Without catalyst
Quinoline
–
0.28 0.02
0.46 0.05
0.54 0.04
1.08 0.05
1.7 0.1
(8 9) 9 10-5
–**
–
–
–
–
–
4.92
5.2
–*
–
0,3 0,02
0.38 0.04
0.62 0.06
0.74 0.02
Pyridine
Triethylamine
Piperidine
10.78
11.2
–
–
* The values for k1 are insignificantly small and therefore not presented
** No cyclization products were observed in reaction with PhSeBr, without catalyst present
aqueous solution (only in case of Lewis bases as additives),
then saturated NaHCO3 aqueous solution and water. The
organic layer was dried over Na2SO4, concentrated and
chromatographed. The product was obtained after the elua-
tion of the traces of diphenyl diselenide from a silica gel-
dichloromethane column. All products were characterized
and identified on the basis of their spectral data [23].
controlled throughout all kinetic experiments to 0.1 °C.
Reactions were performed at 288 K. The solutions of reac-
tants were prepared by measuring calculated amounts of
substances in THF as a solvent. THF is more suitable than
dichloromethane for kinetic experiments in terms of the
boiling point, but for synthetic purpose, it is better to use
dichloromethane which can be removed easily from reaction
mixture. In a quartz cuvette, a certain volume of alcohol
solution was added, then catalyst, and the reaction was ini-
tiated by adding phenylselenenyl halide. During all
experiments, the concentration of phenylselenenyl halide
was kept constant (1 9 10-4 M), while the concentration of
Kinetic measurements
For determination of the rate constants, conventional
kinetics was used. The temperature of reaction mixtures was
123

Struct Chem
PhSeCl
4
3
2
1
0
PhSeBr
10
9
8
7
6
5
4
3
2
1
0
Quinoline
Pyridine
Et3N
Quinoline
Pyridine
Et3N
Piperidine
Piperidine
0
1
2
3
4
5
6
0
1
2
3
4
5
6
103[alkenol]/M
103[alkenol]/M
withoutcatalyst
2
1,5
1
0,5
0
0
1
2
3
4
5
6
103[alkenol]/M
Fig. 4 Pseudo-first-order rate constant, kobsd, as a function of the alkenol concentration for the reaction between 2,6-dimethyl-hept-5en-2-ol and
PhSeX (X = Cl, Br), in the presence and absence of the catalysts
0,4
Quantum chemical calculations
PhSeBr
PhSeCl
Pip
Et3N
0,2
0
All structures were fully optimized at B3LYP/6-311?G**
[27–30] and characterized as transition state structures by
computation of vibrational frequencies (for transition state
structures, exactly one imaginary frequency is present,
NImag = 1). Being well aware of the limitations of DFT
calculations, [31–35] we evaluated the energies by
MP2(fc)/6-311?G** calculations [MP2(fc)/6-311?G**//
B3LYP/6-311?G** ? ZPE(B3LYP/6-311?G**)] [36].
Gaussian 03 suites of programs were used throughout
[37].
pKa
0
2
4
6
8
10
12
-0,2
-0,4
-0,6
-0,8
-1
Py
Pip
Qui
Et3N
Py
Qui
Fig. 5 Bronsted plot of log k2 versus pKa for the catalyzed reaction
between PhSeX and 2,6-dimethyl-hept-5-en-2-ol
alcohol was 5 9 10-3, 4.5 9 10-3, 4 9 10-3, 3.5 9
10-3 and 3 9 10-3 M. In the reactions with catalyst pre-
sent, concentrations of catalysts were equimolar to
phenylselenenyl halide concentration. All reactions were
investigated by following the dependence of the
absorbance on reaction time at suitable wavelength. The
pseudo-first-rate constants, kobsd, were determined accord-
ing to the equation by fitting all kinetic runs as single
exponential function.
Conclusions
Phenylselenoetherification of 2,6-dimethyl-hept-5-en-2-ol
presents a way for the synthesis of the highly substituted
cyclic ether products. These ether units are widespread in
many bioactive natural products. The regioselective out-
come of the reaction can be controlled by the proper choice
of the Lewis base and acid catalyst. The reactivity of the
used Lewis base catalyst depends on their pKa values as
well as on their ability for formation of hydrogen bond with
OH– alcohols group. In addition, quantum chemical cal-
culation have confirmed the preferentially formation of the
tetrahydrofuran ring. Being aware of these findings, the
used methodology can be applied on the wide range of
unsaturated substrates in order to increase the reaction
At ¼ A0 þ ðA0ꢂ A1Þ exp ðꢂkobsdtÞ
The observed pseudo-first-order rate constants were
calculated as the average value from two to five-indepen-
dent kinetic runs using Microsoft Excel and Origin 6.1.
Obtained experimental data are reported in Tables 1S and
2S (Supplementary material).
123

Struct Chem
19. Divac VM, Puchta R, Bugarcic ZM (2012) J Phys Chem A
116:7783–7790
20. Divac VM, Rvovic MD, Bugarcic ZM (2013) React Kinet Catal
110(2):309–316
yield, decrease the reaction time and improve the reaction
selectivity.
Acknowledgments This work was funded by the Ministry of
Education and Science of the Republic of Serbia (Grant: 172011).
R.P. would like to thank the Regionales Rechenzentrum Erlangen
(RRZE) for a generous allotment of computer time, Prof. Tim Clark
for hosting this work at the CCC and Prof. Rudi van Eldik for his
support.
21. Divac VM, Rvovic MD, Jankovic NZ, Bugarcic ZM (2013)
Monatsh Chem 144(8):1227–1231
22. Wirth T, Fragale G, Spichty M (1998) J Am Chem Soc 120:3376
23. Konstantinovic S, Bugarcic Z, Milosavljevic S, Schroth G,
Mihailovic MLJ (1992) Leibigs Ann Chem 261
24. Espenson JH (1995) Chemical kinetics and reaction mechanism,
2nd edn. McGrow Hill, New York
25. Hall HK Jr (1957) J Am Chem Soc 79:5441
26. Brown HC et al (1955) In: Braude EA, Nachod FC (eds) Deter-
mination of organic structures by physical methods. Academic
Press, New York
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