Preparation of tetrasubstituted furans via intramolecular wittig reactions with phosphorus ylides as intermediates

Article abstract of DOI:10.1021/ol101080q

Novel preparation of tetrasubstituted furans, starting from the Michael acceptors, tributylphosphine, and acyl chlorides, is realized. A broad range of highly functional furans can be efficiently generated in one step at room temperature within 10 min to 21 h in moderate to high yields (60-99%). The reaction was proposed to proceed via intramolecular Wittig-type reactions, using phosphorus ylides as intermediates.

Full text of DOI:10.1021/ol101080q

ORGANIC
LETTERS
2010
Vol. 12, No. 13
3066-3069
Preparation of Tetrasubstituted Furans
via Intramolecular Wittig Reactions with
Phosphorus Ylides as Intermediates
Tzu-Ting Kao, Siang-en Syu, Yi-Wun Jhang, and Wenwei Lin*
Department of Chemistry, National Taiwan Normal UniVersity, 88, Section 4,
Tingchow Road, Taipei 11677, Taiwan, Republic of China
wenweilin@ntnu.edu.tw
Received May 11, 2010
ABSTRACT
Novel preparation of tetrasubstituted furans, starting from the Michael acceptors, tributylphosphine, and acyl chlorides, is realized. A broad
range of highly functional furans can be efficiently generated in one step at room temperature within 10 min to 21 h in moderate to high yields
(60-99%). The reaction was proposed to proceed via intramolecular Wittig-type reactions, using phosphorus ylides as intermediates.
Multisubstituted furans are of great importance because
numerous interesting compounds bearing such a heterocyclic
ring exhibit a wide array of activity and are also building
blocks for organic synthesis.1,2 Many synthetic routes toward
furan rings with specific substitution patterns have been
designed and well applied,1c,3 such as direct functionalization
of furan rings,4 cyclocondensation of 1,4-dicarbonyl com-
pounds (Paal-Knorr synthesis),5 Feist-Be´nary synthesis,6
and transition metal-catalyzed cycloisomerization of alkynyl
or allenyl substrates.3a,7 To our surprise, of these developed
strategies,1-8 there are few literature reports for the syntheses
of tetrasubstituted furans with three aryl groups and a ketone,
(1) For recent reviews, see: (a) Hou, X. L.; Yang, Z.; Wong, H. N. C.
Progress in Heterocyclic Chemistry; Gribble, G. W., Joule, J. A., Eds.;
Pergamon: Oxford, UK, 2008; Vol. 19, p 176. (b) Keay, B. A.; Dibble, P. W.
ComprehensiVe Heterocyclic Chemistry II; Katritzky, A. R., Rees, C. W.,
Scriven, E. F. V., Eds.; Elsevier: Oxford, UK, 1997; Vol. 2, p 395. (c) Hou,
X. L.; Cheung, H. Y.; Hon, T. Y.; Kwan, P. L.; Lo, T. H.; Tong, S. Y. T.;
Wong, H. N. C. Tetrahedron 1998, 54, 1955. (d) Keay, B. A. Chem. Soc.
ReV. 1999, 28, 209. (e) Gilchrist, T. L. J. Chem. Soc., Faraday Trans. 1 1999,
(5) Minetto, G.; Raveglia, L. F.; Sega, A.; Taddei, M. Eur. J. Org. Chem.
2005, 5277, and references cited therein.
(6) For selected examples, see: (a) Mross, G.; Holtz, E.; Langer, P. J.
Org. Chem. 2006, 71, 8045. (b) Feist, F. Chem. Ber. 1902, 35, 1537. (c)
Be´nary, E. Chem. Ber. 1911, 44, 489.
2849
.
(7) For selected examples starting from allenyl ketones, see: (a) Dudnik,
A. S.; Gevorgyan, V. Angew. Chem., Int. Ed. 2007, 46, 5195. (b) Hashmi,
A. S. K. Angew. Chem., Int. Ed. Engl. 1995, 34, 1581. For examples from
alkynyl ketone, see: (c) Hashmi, A. S. K.; Schwarz, L.; Choi, J.-H.; Frost,
T. M. Angew. Chem., Int. Ed. 2000, 39, 2285. (d) Marshall, J. A.; Bartley,
G. S. J. Org. Chem. 1994, 59, 7169. (e) Ma, S.; Zhang, J.; Lu, L.
Chem.sEur. J. 2003, 9, 2447. For examples from alkynyl epoxide, see: (f)
Hashmi, A. S. K.; Sinha, P. AdV. Synth. Catal. 2004, 346, 432. For
electrophilic cyclization, see: (g) Sniady, A.; Wheeler, K. A.; Dembinski,
R. Org. Lett. 2005, 7, 1769. For examples from alkynyl alcohols, see: (h)
Liu, Y.; Song, F.; Song, Z.; Liu, M.; Yan, B. Org. Lett. 2005, 7, 5409. For
examples from alkynyl cyclopropyl ketones, see: (i) Zhang, J.; Schmalz,
H.-G. Angew. Chem., Int. Ed. 2006, 45, 6704. For examples from other
substrates, see (j) Peng, L.; Zhang, X.; Ma, M.; Wang, J. Angew. Chem.,
Int. Ed. 2007, 46, 1905. (k) Zhang, M.; Jiang, H.-F.; Neumann, H.; Beller,
M.; Dixneuf, P. H. Angew. Chem., Int. Ed. 2009, 48, 1681.
(2) (a) Lipshutz, B. H. Chem. ReV. 1986, 86, 795. (b) Wong, H. N. C.;
Yu, P.; Yick, C.-Y. Pure Appl. Chem. 1999, 71, 1041. (c) Lee, H.-K.; Chan,
K.-F.; Hui, C.-W.; Yim, H.-K.; Wu, X.-W.; Wong, H. N. C. Pure Appl.
Chem. 2005, 77, 139. (d) Heaney, H. Natural Products Chemistry;
Nakanishi, K., Ed.; Kodansha: Tokyo, Japan, 1974; p 297
.
(3) For recent reviews, see: (a) Kirsch, S. F. Org. Biomol. Chem. 2006,
4, 2076. (b) Brown, R. C. D. Angew. Chem., Int. Ed. 2005, 44, 850. (c)
Cacchi, S. J. Organomet. Chem. 1999, 576, 42
.
(4) For recent examples, see: (a) Melzig, L.; Rauhut, C. B.; Knochel,
P. Chem. Commun. 2009, 3536. (b) Sne´garoff, K.; L’Helgoual’ch, J.-M.;
Bentabed-Ababsa, G.; Nguyen, T. T.; Chevallier, F.; Yonehara, M.;
Uchiyama, M.; Derdour, A.; Mongin, F. Chem.sEur. J. 2009, 15, 10280.
For selected reviews, see: (c) Ila, H.; Baron, O.; Wagner, A. J.; Knochel,
P. Chem. Commun. 2006, 583. (d) Handbook of functionalized organome-
tallics; Knochel, P., Ed.; Wiley-VCH: Weinheim, Germany, 2005
.
10.1021/ol101080q  2010 American Chemical Society
Published on Web 06/03/2010

an ester, or a cyano group.9 Therefore, a strong demand
remains to develop an efficient approach.
Herein, we wish to report a novel preparation of tetrasub-
stituted furans 1, 2, or 3 starting from Bu3P, the corresponding
Michael acceptors 4, 5, or 6, and acid chlorides 7 in the presence
of Et3N in one step (Scheme 1). To the best of our knowledge,
Table 1. Syntheses of Furans 1 from 4 and Acid Chlorides 7a
yield of 1b
entry
R1 (4)
R3 (7)
time (h)
(%)
Scheme 1. Preparation of Fully Functionalized Furans 1, 2, or 3
from 4, 5, or 6, Acid Chlorides 7, and Bu3P in the Presence of Et3N
1
4-NO2C6H4 (4a) 4-NO2C6H4 (7a)
4-NO2C6H4 (4a) 4-BrC6H4 (7b)
4-NO2C6H4 (4a) 4-ClC6H4 (7c)
4-NO2C6H4 (4a) 4-MeC6H4 (7d)
4-NO2C6H4 (4a) 4-MeOC6H4 (7e)
4-NO2C6H4 (4a) 2-furyl (7f)
4-NO2C6H4 (4a) Ph (7g)
1.5
1.5
1.5
1.5
1.5
1.5
3
1aa, 91
1ab, 82
1ac, 86
1ad, 97
1ae, 92
1af, 75
1ag, 98
1bc, 84
1bh, 80
1be, 85
1cf, 71
1cc, 81
1de, 84
1eb,c 79
1ei, 80
1fi, 84
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
4-BrC6H4 (4b)
4-BrC6H4 (4b)
4-BrC6H4 (4b)
4-ClC6H4 (4c)
4-ClC6H4 (4c)
4-ClC6H4 (7c)
2-ClC6H4 (7h)
4-MeOC6H4 (7e)
2-furyl (7f)
4
9
19
21
19
2
18
7
4
17
2
4-ClC6H4 (7c)
4-CNC6H4 (4d) 4-MeOC6H4 (7e)
2-BrC6H4 (4e)
2-BrC6H4 (4e)
2-ClC6H4 (4f)
2-ClC6H4 (4f)
2-furyl (4g)
2-furyl (4g)
2-furyl (4g)
2-thienyl (4h)
CO2Et (4i)
4-BrC6H4 (7b)
2-NO2C6H4 (7i)
2-NO2C6H4 (7i)
4-ClC6H4 (7c)
4-MeOC6H4 (7e)
2-ClC6H4 (7h)
2-furyl (7f)
there are no reports of successful reactions or related studies
that utilize this strategy.10,11 In addition, different kinds of 4,
5, or 6 in combination with various acid chlorides 7 should
make this methodology an attractive approach toward a wide
diversity of substitution patterns in the furan rings.
1fc, 70
1ge, 80
1gh, 93
1gf, 71
1he, 72
1ii, 82
2
21
6
Thus, the Michael acceptor 4a, Bu3P (1.1 equiv), Et3N (1.3
equiv), and the acid chloride 7a (1.1 equiv) reacted smoothly
at room temperature within 1.5 h, furnishing the highly
substituted furan 1aa in 91% yield (Table 1, entry 1).12
Similarly, the reaction of 4a and the other aryl-substituted acid
chlorides bearing an electron-withdrawing group, such as 7b
or 7c, or that with an electron-donating group, like 7d or 7e,
proceeded efficiently at room temperature within 1.5 h, provid-
ing 1ab, 1ac, 1ad, or 1ae in 82%, 86%, 97%, or 92% yield,
respectively (entries 2-5). A heteroaryl-substituted acid chlo-
ride, like 7f, and benzoyl chloride (7g) also worked nicely with
4a in the presence of Bu3P and Et3N within 1.5 or 3 h, giving
1af or 1ag in 75% or 98% yield, respectively (entries 6 and 7).
Other Michael acceptors, such as 4b-i (R1 ) 4-BrC6H4,
4-ClC6H4, 4-CNC6H4, 2-BrC6H4, 2-ClC6H4, 2-furyl, 2-thienyl,
or CO2Et), reacted successfully with various acid chlorides
(7b,c, 7e,f, or 7h,i) within 2-21 h, leading to the corresponding
4-MeOC6H4 (7e)
2-NO2C6H4 (7i)
2
a Reactions were carried out with 4 (0.5 mmol) in THF (2.5 mL) under
nitrogen at rt. b Yield of isolated products. c The structure of 1eb was
confirmed by X-ray analysis (CCDC no. 769220).
products 1 in 70-93% yields (entries 8-22). The steric effect
was observed when an acid chloride, like 7c (R3 ) 4-ClC6H4)
or 7h (R3 ) 2-ClC6H4), participated in our designed reaction
with 4b, furnishing the corresponding furan 1bc or 1bh in 84%
or 80% yield within 4 or 9 h, respectively (entries 8 and 9).
Surprisingly, the expected more challenging case, such as the
reaction of 4e (R1 ) 2-BrC6H4) or 4f (R1 ) 2-ClC6H4) with 7i
(R3 ) 2-NO2C6H4), was successfully achieved within 7 or 4 h,
providing the corresponding furan 1ei or 1fi in 80% or 84%
yield, respectively (entries 15 and 16).
Instead of using the Michael acceptor with the same ketone
functionality (Table 1), the substrate bearing two different
ketone functions, such as 4j, was also studied (Scheme 2).
The reaction of 4j and 7g in the presence of Bu3P and Et3N
(8) For recent selected examples of other tetrasubstituted furans with
2-(1-alkynyl)-2-alken-1-ones as substrates catalyzed by transition metal, see:
(a) Liu, R.; Zhang, J. Chem.sEur. J. 2009, 15, 9303. (b) Xiao, Y.; Zhang,
J. AdV. Synth. Catal. 2009, 351, 617. (c) Xiao, Y.; Zhang, J. Chem. Commun.
2009, 3594. (d) Liu, F.; Zhang, J. Angew. Chem., Int. Ed. 2009, 48, 5505.
(e) Gao, J.; Xhao, X.; Yu, Y.; Zhang, J. Chem.sEur. J. 2010, 16, 456. (f)
Zhang, Y.; Chen, Z.; Xiao, Y.; Zhang, J. Chem.sEur. J. 2009, 15, 5208
.
(9) For the only example of tetrasubstituted furans bearing three phenyl
groups and a ketone function with poor yield, see: (a) Trisler, J. C.; Doty,
J. K.; Robinson, J. M. J. Org. Chem. 1969, 34, 3421. For the only example
of tetrasubstituted furans having three phenyl groups and an ester function
synthesized in multiple steps, see: (b) Tseng, J.-C.; Chen, J.-H.; Luh, T.-Y.
Scheme 2. Preparation of Furans 1jg-a and1jg-b
Synlett. 2006, 1209
.
(10) To the best of our knowledge, there is no report with phosphorous
ylides for the syntheses of furans.
(11) For interesting phosphine-mediated reductive cyclizations of γ-acy-
loxy butynoates to furans, see: Jung, C.-K.; Wang, J.-C.; Krische, M. J.
J. Am. Chem. Soc. 2004, 126, 4118
(12) In our one-step protocol, the addition sequence of reactants has no
influence on the results of the formation of furans.
.
Org. Lett., Vol. 12, No. 13, 2010
3067

proceeded smoothly within 2 h at room tempearture, giving
rise to the fully functionalized furans 1jg-a and 1jg-b in 60%
yield (1jg-a:1jg-b ) 84:16).
Table 3. Syntheses of Furans 3 from 6 and Acid Chlorides 7a
The broad reaction scope of our protocol was demonstrated
by further studies disclosed in Table 2. It showed that the
Table 2. Syntheses of Furans 2 from 5 and Acid Chlorides 7a
yield of 3b
entry
R1 (6)
R3 (7)
time (min)
(%)
1
2
3
4
5
6
7
8
4-NO2C6H4 (6a) 4-ClC6H4 (7c)
4-NO2C6H4 (6a) 2-ClC6H4 (7h)
4-NO2C6H4 (6a) Ph (7g)
10
10
10
10
10
10
40
40
240
10
10
3ac,c 95
3ah, 89
3ag, 88
3bc, 93
3cc, 95
3ch, 85
3dc, 84
3ec, 85
3fh, 84
3gc, 99
3hc, 91
4-ClC6H4 (6b)
4-ClC6H4 (7c)
time yield of 2b
4-CNC6H4 (6c) 4-ClC6H4 (7c)
4-CNC6H4 (6c) 2-ClC6H4 (7h)
4-CH3C6H4 (6d) 4-ClC6H4 (7c)
entry
R1 (5)
R3 (7)
(h)
(%)
1
2
3
4
5
6
7
8
4-NO2C6H4 (5a) 4-NO2C6H4 (7a)
4-NO2C6H4 (5a) 4-BrC6H4 (7b)
4-NO2C6H4 (5a) 4-ClC6H4 (7c)
4-NO2C6H4 (5a) 4-MeC6H4 (7d)
4-NO2C6H4 (5a) 4-MeOC6H4 (7e)
4-NO2C6H4 (5a) 2-NO2C6H4 (7i)
4-NO2C6H4 (5a) 2-ClC6H4 (7h)
4-NO2C6H4 (5a) 3-ClC6H4 (7j)
4-NO2C6H4 (5a) Ph (7g)
2
2
2
2
2
2
2
2
2
2aa, 88
2ab, 94
2ac, 97
2ad, 99
2ae, 93
2ai, 87
2ah, 92
2aj, 94
2ag,c 93
2ak, 70
2bc, 95
2bh, 90
2bf, 75
2bl, 82
2cc, 90
2ce, 85
2ci, 92
2cl, 91
2dc, 86
2dh, 80
2ec, 85
2ee, 80
2el, 80
2fc, 80
2gc, 84
2hc, 88
2ic, 83
2-BrC6H4 (6e)
Ph (6f)
2-furyl (6g)
4-ClC6H4 (7c)
2-ClC6H4 (7h)
4-ClC6H4 (7c)
4-ClC6H4 (7c)
9
10
11
2-thienyl (6h)
a Reactions were carried out with 6 (0.5 mmol) in THF (2.5 mL) under
nitrogen at rt. b Yield of isolated products. c The structure of 3ac was
confirmed by X-ray analysis (CCDC no. 769770).
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
4-NO2C6H4 (5a) CH3 (7k)
4
furnished at room temperature within 10-40 min in 84-99%
yields (entries 1-8, 10, and 11), except for 3fh (84% yield;
4 h; entry 9).
Furthermore, acryloyl chloride (7m), which was prone to
undergo polymerization catalyzed by Bu3P, reacted success-
fully with 6b, Bu3P, and Et3N at room temperature within
40 min, leading to the corresponding furan 3bm in 72% yield
(Scheme 3). Interestingly, the reaction of terephthaloyl
4-BrC6H4 (5b)
4-BrC6H4 (5b)
4-BrC6H4 (5b)
4-BrC6H4 (5b)
4-CNC6H4 (5c)
4-CNC6H4 (5c)
4-CNC6H4 (5c)
4-CNC6H4 (5c)
2-BrC6H4 (5d)
2-BrC6H4 (5d)
2-furyl (5e)
4-ClC6H4 (7c)
2-ClC6H4 (7h)
2-furyl (7f)
12
12
12
8
4
4
4
4
12
12
12
4
2-thienyl (7l)
4-ClC6H4 (7c)
4-MeOC6H4 (7e)
2-NO2C6H4 (7i)
2-thienyl (7l)
4-ClC6H4 (7c)
2-ClC6H4 (7h)
4-ClC6H4 (7c)
4-MeOC6H4 (7e)
2-thienyl (7l)
4-ClC6H4 (7c)
2-furyl (5e)
2-furyl (5e)
2-thienyl (5f)
Scheme 3
.
Preparation of Highly Functionalized Furans 3bm
and 3bn
9
12
12
12
4
1-naphthyl (5g) 4-ClC6H4 (7c)
2-naphthyl (5h) 4-ClC6H4 (7c)
CO2Et (5i)
4-ClC6H4 (7c)
a Reactions were carried out with 5 (0.5 mmol) in THF (2.5 mL) under
nitrogen at rt. b Yield of isolated products. c The structure of 2ag was
confirmed by X-ray analysis (CCDC no. 768639).
reactions of Michael acceptors bearing a ketone and an ester
group, like 5a-i (R1 ) 4-NO2C6H4, 4-BrC6H4, 4-CNC6H4,
2-BrC6H4, 2-furyl, 2-thienyl, 1-naphthyl, 2-naphthyl, or
CO2Et), and acid chlorides 7a-l (1.1 equiv) in the presence
of Bu3P (1.1 equiv) and Et3N (1.3 equiv) took place in 2-12
h, leading to the corresponding adducts 2 in 70-99% yields
(entries 1-27).
Remarkably, the Michael acceptor 6 having a ketone and
a cyano group exhibited a significant enhancement in
reactivity for the formation of the corresponding furan 3 in
comparison with 4 or 5 for the formation of the correspond-
ing furan 1 or 2. Excellent results, for example, using 6a-h
and 7c, 7g, or 7h for syntheses of furans 3, were shown in
Table 3. Under the same reaction condition for the prepara-
tion of 1 or 2, the corresponding furans 3 were efficiently
chloride (7n) and 6b in the presence of Bu3P and Et3N
occurred smoothly at room temperature within 4 h, providing
the corresponding furan 3bn in 60% yield.
On the basis of experimental results (Tables 1-3, Schemes
2 and 3), a plausible reaction mechanism was proposed
(Scheme 4). First, the Michael addition of Bu3P toward 4,
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Org. Lett., Vol. 12, No. 13, 2010

Scheme 4
.
A Proposed Mechanism for the Formation of 1, 2, or 3
Scheme 6
.
Preparation of Furans 1kc, 2ac, and 3bc from 8k
(or 17), 9a, and 10b
equiv; 1 N in dioxane), the adduct 17 was obtained in
quantitative yield.15
5, or 6 took place, giving rise to the corresponding zwitterion
8, 9, or 10. The intermediate 8, 9, or 10 was acylated with
an acid chloride 7, leading to the formation of 11, 12, or 13.
Then deprotonation of 11, 12, or 13 by Et3N occurred, and
the resulting ylide 14, 15, or 16 underwent an intramolecular
Wittig reaction, affording the corresponding furan 1, 2,
or 3.13
The proposed reaction mechanism for the formation of
furan 1, 2, or 3 can be confirmed in our preliminary studies
(Schemes 5 and 6). The intermediate zwitterion, such as 8k,
Besides, the reaction of the intermediate zwitterion, such
as 8k, 9a, or 10b, and an acid chloride, such as 7c, in the
presence of Et3N (1.3 equiv) indeed took place smoothly at
room temperature within 20 h, 2 h, or 10 min, giving the
corresponding furan 1kc, 2ac, or 3bc in 74%, 95%, or 94%
yield, respectively (Scheme 6). The reaction of the phos-
phonium chloride 17 and 7c in the presence of Et3N (3.0
equiv) also took place smoothly, providing 1kc in good yield
(75%). All of this evidence showed that a zwitterion like 8,
9, or 10 was the intermediate for the formation of the
corresponding furan 1, 2, or 3 (Schemes 5 and 6).
Scheme 5. Preparation of 8k, 9a, 10b, 10f, and 17
In conclusion, we have developed a general procedure for
novel syntheses of tetrasubstituted furans 1, 2, or 3. The
reaction condition is very mild, and numerous Michael
acceptors 4, 5, or 6 and acid chlorides 7 can be applied
efficiently in one step to afford 1, 2, or 3 in high yields. The
reaction mechanism is proposed to undergo the Michael
reaction of Bu3P and 4, 5, or 6 followed by acylation with
8, 9, or 10, deprotonation of the corresponding intermediate
11, 12, or 13, and finally an intramolecular Wittig reaction
of 14, 15, or 16. In addition, the easy access to acid chlorides
7 as well as Michael acceptors 4, 5, or 6, which result from
the condensation of aldehydes and 1,3-diketone, ethyl
benzoylacetate, or benzoylacetonitrile, makes our protocol
an attractive approach toward a wide diversity of substitution
patterns in the furan rings. Further studies and the extensions
of this concept in the preparation of other heterocycles are
currently underway.
9a, 10b, or 10f, resulted effectively from the addition of Bu3P
toward 4k, 5a, 6b, or 6f, and 8k, 9a, and 10f were
characterized with X-ray crystallography (Scheme 5).14,15
When 4k was treated with Bu3P (1.1 equiv) and HCl (1.1
Acknowledgment. The authors thank the National Science
Council of the Republic of China (NSC Grant No. 97-2113-
M-003-003-MY2) and National Taiwan Normal University
(98031013) for financial support.
(13) For selected reviews of Wittig reactions, see: (a) Hoffmann, R. W.
Angew. Chem., Int. Ed. 2001, 40, 1411. (b) Lawrence, N. J. Preparation of
Alkenes: a Practical Approach; Williams, J. M. J., Ed.; Oxford University
Press: Oxford, UK, 1995. (c) Phosphorus Ylides: Chemistry and Applications
in Organic Chemistry; Kolodiazhnyi, O. I., Ed.; Wiley-VCH: New York,
1999.
Supporting Information Available: General experimental
procedures, compound characterization data, and X-ray and
NMR spectra. This material is available free of charge via
the Internet at http://pubs.acs.org.
(14) For another method to prepare the phosphonium enolate zwitterions
of type 9 starting from tertiary phosphines, 4-pyridinecarboxaldehyde (3
equiv), and alkynoates (1 equiv) within 0.5-12 h, please see: Zhu, X.-F.;
Henry, C. E.; Kwon, O. J. Am. Chem. Soc. 2007, 129, 6722.
(15) The structures of adducts 8k, 9a, 10f, and 17 were confirmed by
1H, 13C, and 31P NMR and X-ray analyses (CCDC no. 769222 for 8k,
771901 for 9a, 768638 for 10f, and 746224 for 17).
OL101080Q
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