Stereoselective synthesis of (+)-decarestrictine L

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Aug 19, 2016 - 30 min, 88%. 4. O. 1) DIBAL-H, CH2Cl2. 0 oC, 1 h. 2) Ph3PCH3Br, KOtBu,. THF, 0 oC, 1 h, 89%. OH. 3. Scheme 3. Synthesis of compound 3. O.
Tetrahedron Letters 57 (2016) 4368–4370

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Stereoselective synthesis of (+)-decarestrictine L using tandem isomerization followed by C–O and C–C bond formation reaction Shivalal Banoth a,b, Suresh Kanikarapu a, Jhillu S. Yadav a,b, Debendra K. Mohapatra a,b,⇑ a b

Natural Products Chemistry Division, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India Academy of Scientific and Innovative Research, New Delhi 110001, India

a r t i c l e

i n f o

Article history: Received 5 July 2016 Revised 13 August 2016 Accepted 17 August 2016 Available online 19 August 2016 Keywords: Natural products Tandem reaction trans-2,6-Disubstituted dihydropyran Mitsunobu inversion Wacker’s oxidation

a b s t r a c t A stereoselective synthesis of the (+)-decarestrictine L has been described following our own developed iodine-catalyzed tandem isomerization followed by C–O and C–C bond formation reaction for the construction of trans-2,6-disubstituted dihydropyran as the key step. Other important reactions used for this synthesis are 5-exo-trig-iodolactonization, Mitsunobu inversion, and Wacker’s oxidation. The total synthesis of the target molecule was achieved in 10 linear steps with 28% overall yield. Ó 2016 Elsevier Ltd. All rights reserved.

The secondary metabolites of (+)-decarestrictines were isolated from various Penicillium strains and identified as bioactive compounds by chemical screening.1 Several members of the decarestrictine family of natural products have been shown to inhibit the biosynthesis1a,2 of cholesterol in both a HEP-G2 liver cell assay and in vivo.1c,d Of the 15 decarestrictines isolated to date, 13 possess a 10-membered lactone core.1a,b The major components of this family show a 10-membered lactone ring system, while decarestrictine L (1) has a tetrahydropyran structure (Fig. 1).1–3 The relative configuration of natural (+)decarestrictine L was established by NMR,1 and its absolute configuration (+)-(2R,3S,6R) was confirmed by its total synthesis (Kibayashi et al. following oxa-Michael reaction in 10 steps with 2.3% overall yield).4 Several other syntheses5 of decarestrictine L (1) have been reported. Clark et al.5a followed carbenoid insertion and ylide rearrangement (9 steps, 5.5%), Nokami et al.5b used sulfinyl anion addition and [2,3]-rearrangement (7 steps, 11%), Carreno et al.5c followed a-hydroxy ketone reduction (18 steps, 16%), Hatakeyama et al.5d applied Sharpless dihydroxylation (20 steps, 10%), Donaldson et al.5e used stereoselective axial methylation (13 steps, 6.3%), Clark et al.5f utilized oxonium ylide rearrangement (10 steps, 10%), Fall et al.5g used stereoselective Michael (12 steps, 21%), Sudalai et al.5h applied D-prolinecatalyzed a-aminooxylation (7 steps, 22%), Burke et al.5k utilized ⇑ Corresponding author. Tel.: +91 40 27193128; fax: +91 40 27160512. E-mail address: [email protected] (D.K. Mohapatra). http://dx.doi.org/10.1016/j.tetlet.2016.08.055 0040-4039/Ó 2016 Elsevier Ltd. All rights reserved.

asymmetric hydroformylation (6 steps, 27%). Although, there are many syntheses reported in the literature, they suffer from one or more disadvantages, which include the use of expensive chiral ligands, long reaction sequences, poor selectivity, and low yields.6 As a part of our ongoing research on total synthesis of pyran ring containing biologically active natural products7 using our own developed methodology of tandem isomerization followed by C–O and C–C bond formation reaction, herein, we report an efficient synthesis of (+)-decarestrictine L (1) in a highly stereoselective manner). As per the retrosynthetic route for (+)-decarestrictine L (1), the keto functionality in compound 1 could be introduced via Wacker’s oxidation of double bond present in intermediate 2 which would be obtained from compound 3 following the Mitsunobu inversion reaction. The functionalized pyran 3 could be obtained from bicyclic lactone 4 via C1-Wittig homologation which could be synthesized from 5 by employing a 5-exo-trig-iodolactonizat-ion as key reaction. The required precursor 5 in turn would be synthesized from commercially available chiral homoallylic alcohol 6 (Scheme 1). The synthesis of the key intermediate 5 began with commercially available homoallyl alcohol 6 and acrolein 7 which on treatment with Hoveyda-Grubbs catalyst (10 mol %) in CH2Cl2 gave cross metathesis8 product d-hydroxy a,b-unsaturated aldehyde 8 in 86% yield. The tandem cyclization protocol was performed by subjecting 8 with allyltrimethylsilane in the presence of catalytic amount of iodine in anhydrous THF at room temperature to furnish

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S. Banoth et al. / Tetrahedron Letters 57 (2016) 4368–4370 O

O O

OH O

HO

(R)

HO

OH

7

Hoveyda-Grubbs II CH2 Cl2 , rt, 86%

6

O

OH

Decarestrictine A

Decarestrictine D O

O

O

OH

O

(R)

O 8

Si I2, rt, 45 min 94%

O

O 5

HO OH

OH Decarestrictine C

Scheme 2. Synthesis of trans-2,6-disubstituted dihydropyran 5.

Decarestrictine L

Figure 1. Representative members of the decarestrictine family of natural products.

1) NaIO4 , 2,6-lutidine OsO 4, dioxane:H2 O (3:1), rt, 3 h O

trans-2,6-disubstituted-3,4-dihydropyran 5 as the sole product in 94% yield (Scheme 2).9 To predict the formation of the trans-2,6disubstituted-3,4-dihydropyran 5 from d-hydroxy a,b-unsaturated aldehyde 8 following catalytic pathways, we postulated like earlier9 that the product could be generated with the activation of aldehyde and isomerization10 by in situ formation of catalytic amount of TMSI followed by subsequent formation of an oxocarbenium intermediate in which the stereoelectronic and/or steric factors dictate the direction of the incoming nucleophile. Regioselective oxidative cleavage of terminal double bond present in 5 was performed using OsO4, 2,6-lutidine, and NaIO4 following Jin’s one-pot protocol11 to obtain the corresponding aldehyde, which on subsequent oxidation under the Pinnick conditions12 gave the acid 9 in 81% yield over two steps. The installation of hydroxyl group was achieved by a cis-selective 5-exo-trigiodolactonization reaction following our previous reported reaction conditions7b as applied in the synthesis of C21–C29 fragment of sorangicin A. After achieving the cis-iodolactone 10 as a single diastereomeric product in 87% yield, deiodination was carried out following Barton–McCombie protocol by treating 10 with tri-n-butyltin hydride and a catalytic amount of AIBN in toluene under reflux conditions to give 4 in 88% yield (Scheme 3).13 Reduction of lactone with DIBAL-H at 0 °C followed by exposure of the resulting lactol to the one carbon Wittig homologation using methyltriphenylphosphonium bromide in the presence of potassium tert-butoxide14 provided olefin 3 in good overall yield (89% over two steps). Our next target was to invert the stereogenic center of secondary hydroxyl group present in compound 3 under the Mitsunobu conditions.15 Accordingly, the alcohol 3 was treated with PPh3, DEAD, and p-NBA to afford benzoyl ester 11 as the sole product with inverted configuration at the hydroxyl-bearing stereogenic center in 78% yield. Wacker’s oxidation of terminal alkene of compound 11 in the presence of PdCl2, CuCl under oxygen atmosphere in DMF furnished ketone 12 in 87% yield (Scheme 4).16 Finally, saponification of the ester moiety present in 12 with potassium carbonate in methanol gave (+)-decarestrictine L (1) in 92%

Wacker oxidation OH OH O O

O 1

2 exo-tri g iodolactonization

O 3

2) NaClO2 , NaH 2PO 4 2-methyl-2-butene 0 o C-rt, 81%

5

I I 2 , KI, NaHCO3

n-Bu3 SnH, AIBN

O O

H2 O, rt, 12 h 87%

OH

toluene, reflux, 30 min, 88%

O 10

O O O 4

OH

1) DIBAL-H, CH 2 Cl2 0 o C, 1 h

O 3

2) Ph 3PCH3 Br, KO tBu, THF, 0 oC, 1 h, 89%

Scheme 3. Synthesis of compound 3.

O 2N OH

O

p-O 2NC 6H 4CO2 H, DEAD O

O 3

PPh 3, THF, rt, 45 min, 78% O 11

O 2N O PdCl2 , CuCl, O 2 DMF, rt, 4 h, 87%

O O 12

O

OH O

K2CO3 , MeOH rt, 1 h, 92%

O 1

Scheme 4. Completion of the total synthesis of (+)-decarestrictine L (1).

yield. The spectroscopic and optical rotation data of synthetic compound 1 are in good agreement with the natural product.1 In summary, a stereoselective synthesis of the (+)-decarestrictine L has been described following our recently developed iodine-catalyzed tandem isomerization followed by C–O and C–C bond formation reaction for the construction of trans-2,6-disubstituted dihydropyran as the key step. The target molecule was synthesized in 10 linear steps with 28% overall yield. The other key reactions such as 5-exo-trig-iodolactonization was utilized for the introduction of the hydroxyl group, the Mitsunobu reaction for the inversion of the hydroxyl center and the Wacker oxidation reaction for the introduction of keto functionality. The protocol can be applied for the synthesis of other natural products having tetrahydropyran ring system as well as the synthesis of decarestrictine L analogs for further biological screening.

OH

O O O 4

OH

O O 9

O 5

(R)

6

Isomerization and C-O/C-C bond formation

Scheme 1. Retrosynthetic analysis of (+)-decarestrictine L.

Acknowledgments The authors thank the Council of Scientific and Industrial Research (CSIR), New Delhi, India for financial support as Part of XII Five Year Plan Programme under title ORIGIN (CSC-0108). S.B.

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and K.S. thanks the Council of Scientific and Industrial Research (CSIR), New Delhi, India, for financial assistance in the form of research fellowship. Supplementary data

6. 7.

Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.tetlet.2016.08. 055. References and notes 1. (a) Grabley, S.; Granzer, E.; Hütter, K.; Ludwig, D.; Mayer, M.; Thiericke, R.; Till, G.; Wink, J.; Philipps, S.; Zeeck, A. J. Antibiot. 1992, 45, 56; (b) Göhrt, A.; Zeeck, A.; Hütter, K.; Kirsch, R.; Kluge, H.; Thiericke, R. J. Antibiot. 1992, 45, 66; (c) Grabley, S.; Hammann, P.; Hütter, K.; Kirsch, R.; Kluge, H.; Thiericke, R.; Mayer, M.; Zeeck, A. J. Antibiot. 1992, 45, 1176; (d) Mayer, M.; Zeeck, A. J. Chem. Soc., Perkin Trans. 1993, 1, 495. 2. Mayer, M.; Thiericke, R. J. Antibiot. 1993, 46, 1372. 3. Andrus, M. B.; Shih, T. L. J. Org. Chem. 1996, 61, 8780. 4. Machinaga, N.; Kibayashi, C. Tetrahedron Lett. 1993, 34. 5. (a) Clark, J. S.; Whitlock, G. A. Tetrahedron Lett. 1994, 35, 6381; (b) Nokami, J.; Taniguchi, T.; Ogawa, Y. Chem. Lett. 1995, 43; (c) Solladie, G.; Arce, E.; Bauder, C.; Carreno, M. C. J. Org. Chem. 1998, 63, 2332; (d) Esumi, T.; Kimura, R.; Mori, M.; Iwabuchi, Y.; Irie, H.; Hatakeyama, S. Heterocycles 2000, 52, 525; (e) Lukesh, J. M.; Donaldson, W. A. Tetrahedron Asymmetry 2003, 14, 757; (f) Clark, J. S.; Fessard, T. C.; Whitlock, G. A. Tetrahedron 2006, 62, 73; (g) Garcia, I.; Gomez, G.; Teijeira, M.; Teran, C.; Fall, Y. Tetrahedron Lett. 2006, 47, 1333; (h) Rawat, V.; Chouthaiwale, P. V.; Suryavanshi, G.; Sudalai, A. Tetrahedron Asymmetry 2009,

8.

9. 10. 11. 12. 13. 14. 15. 16.

20, 2173; (i) Zúñiga, A.; Pérez, M.; Pazos, G.; Gómez, G.; Fall, Y. Synthesis 2010, 2446; (j) Chatterjee, S.; Ghadigaonkar, S.; Sur, P.; Sharma, A.; Chattopadhyay, S. J. Org. Chem. 2014, 79, 8067; (k) Risi, R. M.; Maza, A. M.; Burke, S. D. J. Org. Chem. 2015, 80, 204. Riatto, V. B.; Pilli, R. A.; Victor, M. M. Tetrahedron 2008, 10, 2279. (a) Banoth, S.; Maity, S.; Kumar, S. R.; Yadav, J. S.; Mohapatra, D. K. Eur. J. Org. Chem. 2016, 2300; (b) Mohapatra, D. K.; Banoth, S.; Yadav, J. S. Tetrahedron Lett. 2015, 56, 5930; (c) Mohapatra, D. K.; Maity, S.; Banoth, S.; Gonnade, R. G.; Yadav, J. S. Tetrahedron Lett. 2016, 57, 53; (d) Reddy, D. S.; Padhi, B. K.; Mohapatra, D. K. J. Org. Chem. 2015, 80, 1365; (e) Mohapatra, D. K.; Krishnarao, P. S.; Bhimireddy, E.; Yadav, J. S. Synthesis 2014, 46, 1639; (f) Pradhan, T. R.; Das, P. P.; Mohapatra, D. K. Synthesis 2014, 46, 1177; (g) Mohapatra, D. K.; Maity, S.; Rao, T. S.; Yadav, J. S.; Sridhar, B. Eur. J. Org. Chem. 2013, 2859; (h) Yadav, J. S.; Pattanayak, M. R.; Das, P. P.; Mohapatra, D. K. Org. Lett. 2011, 13, 1710; (i) Mohapatra, D. K.; Bhimireddy, E.; Krishnarao, P. S.; Das, P. P.; Yadav, J. S. Org. Lett. 2011, 13, 744. (a) Garber, S. B.; Kingsbury, J. S.; Gray, B. L.; Hoveyda, A. H. J. Am. Chem. Soc. 2000, 122, 8168; (b) Dinh, M. T.; Bouzbouz, S.; Peglion, J. L.; Cossy, J. Tetrahedron 2008, 64, 5703. Mohapatra, D. K.; Das, P. P.; Pattanayak, M. R.; Yadav, J. S. Chem. Eur. J. 2010, 16, 2072. Xiang, L.; Yang, Y.; Zhou, X.; Liu, X.; Li, X.; Kang, X.; Yan, R.; Huang, G. J. Org. Chem. 2014, 79, 10641. Yu, W.; Mei, Y.; Kang, Y.; Hua, Z.; Jin, Z. Org. Lett. 2004, 6, 3217. (a) Ballakrishna, S. B.; Childers, W. E.; Pinnick, H. W., Jr. Tetrahedron 1981, 37, 2091; (b) Dalcanale, E.; Montanari, F. J. Org. Chem. 1986, 51, 567. Schultz, A. G.; Kirincich, S. J. J. Org. Chem. 1996, 61, 5626. Choi, W. J.; Moon, H. R.; Kim, H. L.; Yoo, B. N.; Lee, J. A.; Shink, D. H.; Jeong, L. S. J. Org. Chem. 2004, 69, 2634–2636. Dodge, J. A.; Trujillo, J. I.; Presnell, M. J. Org. Chem. 1994, 35, 6381. Tsuji, J.; Shimizu, I.; Yamamoto, K. Tetrahedron Lett. 1976, 2975.