Pd(II) - Catalysed Cyclisations in the Total Synthesis of Natural Products
Pd(II) - Catalysed Cyclisations in the Total Synthesis of Natural Products
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Transcript of Pd(II) - Catalysed Cyclisations in the Total Synthesis of Natural Products
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Pd(II)Pd(II)--Catalysed CyclisationsCatalysed Cyclisations in in thethe
Total Synthesis of Natural Total Synthesis of Natural ProductsProducts
Dr. Peter SzolcsányiDr. Peter SzolcsányiDepartment of Organic ChemistryDepartment of Organic ChemistrySSlovak lovak UUniversity of Technologyniversity of Technology
BratislavaBratislava, Slovak Republic, Slovak Republic
XII. Blue Danube Symposium on Heterocyclic ChemistryXII. Blue Danube Symposium on Heterocyclic ChemistryJune 10June 10thth - 13 - 13thth, 2007, 2007 Tihany, Hungary Tihany, Hungary
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Pd(II)-activation of C=C bond and subsequentPd(II)-activation of C=C bond and subsequenttransformationstransformations
YH
Y=O, NPG
YH
PdX2L2+ PdX2L2
- HX
YPdXL2
-Pd-complex
-Pd-complex
+ CO
Y
-Pd-CO-complex
PdXL2
O
(T < -20°C)
R R
R
R
+ CuX2
- PdX2Y
X
R
Y=NPG, X=Cl, Br
+ MeOH
Y OMe
OR
R=OH
Y
O
O
-H--elim.
Y
R
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Versatility of Pd(II)-catalysed cyclisationsVersatility of Pd(II)-catalysed cyclisationsof aminoalkenesof aminoalkenes
Pd(II)/CuCl2
NH
PG
R2
N
PG
ClN
O
PG
Pd(II)/C
uCl 2
R 2=OH
R1
CO/Pd(II
)
MeOHN
PG
CO/Pd(II)R1 =OH
N
PG
O
O
OMe
O
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Synthesis of (un)natural piperidine alkaloidsSynthesis of (un)natural piperidine alkaloids
(+)-EPIPINIDINONE
(defense alkaloid and deterent ofC. montrouzieri and E. varivestis)
(+)-CALVINE
(defense alkaloid and deterent ofC. 10-guttata and C. 14-guttata)
NH
OH
homo-1-DNJ
OH
HO
OH
(analogues of glucosidase inhibitor 1-deoxynojirimycin from Morus sp.)
NH
OH
Cl
6-Cl-L-ido-1-DNJ
OH
HO
NH
O
NC5H11
OO
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TTotal synthesis of otal synthesis of unnaturalunnaturalanalogues of 1-deoxynojirimycinanalogues of 1-deoxynojirimycin
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1-Deoxynojirimycin1-Deoxynojirimycin
White mulberry(Morus alba)
Inhibition: Ki = 32 nM (-D-glucosidase)Activity: anti-diabetes, anti-HIV, ...Applications: Tay-Sachs, Gaucher, ...
NH
1-Deoxynojirimycin(1,5-dideoxy-1,5-imino-D-glucitol)
OH
OH
OHHO
Reference: Iminosugars as Glycosidase Inhibitors: Nojirimycin and Beyond, Ed. A. E. Stütz, Wiley, 1999.
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Retrosynthetic analysisRetrosynthetic analysis of new analogues of 1 of new analogues of 1--DNJDNJ
NH
OH
homo-1-DNJ
OH
HO
OH NPG
OPG
PGO O
O
NHPG
OH
OPG
PGO
NH
OH
Cl
6-Cl-L-ido-1-DNJ
OH
HO
NHPG
OH
OPG
PGO
SUGAR
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SSubstrateubstrate p preparationreparation
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Pd(II)-catalysed aminocarbonylation & Finalisation
P. Szolcsányi et al.: Tetrahedron: Asymmetry 2000, 11, 2579.
OH
OBn
OBn
NHBnNBn
OBn
BnO
CO (balloon)0.1 eq. PdCl2
1 eq. BQ
2 eq. LiCl2 eq. AcONa
THF, r.t.17 hrs, 66%
D-gluco L-ido(4 : 1)
O
O
NBn
OBn
BnO O
O+
NBn
OBn
BnO O
O
1. LiBH4, THF 0°C - r.t., 64%
2. H2 (balloon) 10% Pd/C, HCl
MeOH, r.t., 90%
N
H.HCl
OH
homo-1-DNJ
OH
HO
OH
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Pd(II)Pd(II)//CuClCuCl22-catalysed chlorocyclisation-catalysed chlorocyclisation
OH
OBn
OBn
NHBnNBn
OBn
BnO OH
ClNBn
OBn
BnO OH
Cl
0.1 eq. PdCl23 eq. CuCl2
3 eq. AcONaglacial AcOH
r.t., 2 days, 70%
+
L-ido D-gluco(19 : 1)
OH
OBn
OBn
NHBn
NBn
OBn
BnO OH
Cl
0.1 eq. PdCl23 eq. CuCl2
3 eq. AcONar.t., DMF, 53%
NBn
OBn
BnO OH
Cl+
L-altro D-galacto
+
NBn
BnO OH
O
(11%)(15 : 1)
P. Szolcsányi, T. Gracza: Tetrahedron 2006, 62, 8498.
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Mechanistic proposal of the Pd(II)/CuClMechanistic proposal of the Pd(II)/CuCl22-catalysed-catalysedchloroaminocyclisation and bicyclisationchloroaminocyclisation and bicyclisation
Si-attack Re-attack
BnHNBnO
BnO
OH
HClHCl
-Pd-complex I-Pd-complex II
CuCl2CuCl2
-Pd/Cu-complex I
NHBn
BnO
OBn
OHH
Cl2Pd
NBn
BnO
OBn
OH
Pd
Cl
NBn
BnO
OBn
OH
Pd
Cl
Cl
CuCl
NHBn
BnO
OBn
OHH PdCl2
NBn
BnO
OBn
OHPdCl
NBn
BnO
OBn
OH
-Pd/Cu-complex II
Cu Cl
Pd
Cl
Cl
L2PdCl2 L2PdCl2
CHLOROCYCLISATION BICYCLISATION
D-galacto
BICYCLECHLORIDE
P. Szolcsányi, T. Gracza: Chem. Commun. 2005, 3948.
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Synthesis of new analogues ofSynthesis of new analogues of iminoalditols iminoalditols
P. Szolcsányi, T. Gracza: Tetrahedron 2006, 62, 8498.
NBn
OHO
H2 (1 atm)10 % Pd/C
EtOH, HCl100 %
L-altro
H2 (1 atm)10 % Pd/C
EtOH, HCl100 %
NH.HCl
OHO
D-galacto
BnO HO
N
OBn
BnO Bn
HO
Cl
1C4 (J4,5 = 10.4 Hz)(J2,3 ~ J3,4 = 3.5 Hz)
N
OH
HO H.HCl
HO
Cl
H2 (1 atm)10 % Pd/C
EtOH, HCl100 %
L-idoN
OBn
BnO BnCl
HO
1C4 (J4,5 = 3.0 Hz)(J2,3 ~ J3,4 = 4.8 Hz)
N
OH
HO H.HClCl
HO
1C4 (J4,5 = 1.5 Hz)(J2,3 ~ J3,4 = 3.5 Hz)
1C4 (J3,4 = 2.3, J4,5 = 6.7 Hz)
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Formal tFormal total synthesis ofotal synthesis of alkaloid (+)- alkaloid (+)-2-2-eepipipinidinonepinidinone
NH
(2R,6R)/(2S,6R)-6-methyl-2-(2,-oxo-propyl)piperidine
O
(-)-Pinidinone
NH
O
(+)-2-Epipinidinone
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Ladybird Beetles (Coccinellidae)
Mealybug ladybird beetle
(Cryptolaemus montrouzieri)
Mexican bean beetle
(Epilachna varivestis)
Reports on (epi)pinidinone occurrence:
V. W. Brown, P. B. Moore: Aust. J. Chem. 1982, 35, 1255.
A. B. Attygalle, S. Ch. Xu, K. D. McCormick, J. Meinwald, C. L. Blankespoor, T. Eisner: Tetrahedron 1993, 49, 9333.
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Coniferous Trees (Pinaceae)
Ponderosa pine(Pinus ponderosa)
Colorado spruce(Picea pungens)
Reports on (epi)pinidinone occurrence:
J. N. Tawara, A. Blokhin, T. A. Foderaro, F. R. Stermitz, J. Org. Chem. 1993, 58, 4813.
F. R. Stermitz, J. N. Tawara, M. Boeckl, M. Pomeroy, T. A. Foderaro, F. G. Todd, Phytochemistry1994, 35, 951.
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Retrosynthetic analysisRetrosynthetic analysis of of (+)-2-epipinidinone(+)-2-epipinidinone
NH
O
(+)-2-Epipinidinone
NPG
OMe
O
NHPG
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Formal tFormal total synthesisotal synthesis of (+)-2-epipinidinone of (+)-2-epipinidinone
Substrate preparation: D. J. Dixon, S. V. Ley, W. E. Tate: J. Chem. Soc., Perkin Trans. 1 2000, 2385.
A. Fürstner, K. Langemann: Synthesis 1997, 792.
a) Preparation of the substrate and its Pd(II)-catalysed methoxycarbonylation
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Formal tFormal total synthesisotal synthesis of (+)-2-epipinidinone of (+)-2-epipinidinone
Debenzylation: T. Momose, N. Toyooka, J. Makoto: J. Chem. Soc., Perkin Trans. 1 1997, 2005.
Finalisation: M. J. Munchhof, A. I. Meyers: J. Am. Chem. Soc. 1995, 117, 5399.
H2 (balloon)0.15 eq. Pd(OH)2
MeOH, 18 hrs, 62%NBn
OMe
O
NH
OMe
O 1. Weinreb
2. MeMgBr NH
O
(+)-2-epipinidinone
b) Deprotection and completion of the formal synthesis
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Short tShort total synthesis of otal synthesis of racemicracemicalkaloids calkaloids calvine and 2-alvine and 2-eepicalvinepicalvine
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Ladybird Beetles (Ladybird Beetles (CoccinellidaeCoccinellidae))[1][1]
Calvia 10-guttata
Calvia 14-guttata
These insects are rarely eaten by predators due to the production of toxic alkaloids in their haemolymph. When disturbed or molested, they release small droplets of yellow “blood” at their knee joints (so called reflex bleeding) [2]
[1] A. G. King, J. Meinwald: Chem. Rev. 1996, 96, 1105.
[2] G. M. Happ, T. Eisner: Science 1961, 134, 329.
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SStructure elucidation of (+)-tructure elucidation of (+)-ccalvine and (+)-2-alvine and (+)-2-eepicalvinepicalvine
The relative configuration was established on the basis of NMR and HRMS studies and subsequently confirmed via racemic total synthesis.[3] The absolute configuration was determined by enantioselective total synthesis.[4]
[3] J.-C. Braekman, A. Charlier, D. Daloze, S. Heilporn, J. Pasteels, V. Plasman, S. Wang: Eur. J. Org. Chem. 1999, 1749.
[4] P. Laurent, J.-C. Braekman, D. Daloze: Eur. J. Org. Chem. 2000, 2057.
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• Known total syntheses of (+)-Known total syntheses of (+)-ccalvine and (+)-2-alvine and (+)-2-eepicalvinepicalvine
a) CN(R,S)-methodology - use of chiral N-cyanomethyloxazolidine12% total yield over 7 stepsP. Laurent, J.-C. Braekman, D. Daloze: Eur. J. Org. Chem. 2000, 2057.
b) CM-strategy - olefin cross-metathesis reaction15% total yield over 9 stepsP. Dewi-Wülfling, J. Gebauer, S. Blechert: Synlett 2006, 487.
• Known Known formalformal syntheses of (+)- syntheses of (+)-ccalvine and (+)-2-alvine and (+)-2-eepicalvinepicalvine
c) Davies‘ Li-amide 1,4- addition & Intramolecular Mannich-type reactionS. Rougnon-Glasson, Ch. Tartrat, J.-C. Canet, P. Chalard, Y. Troin:Tetrahedron:Asymmetry 2004, 15, 1561.
d) Diastereoselective reduction of piperidine -enamino estersS. Calvet-Vitale, C. Vanucci-Bacqué, M.-C. Fargeau-Bellassoued, G. Lhommet:Tetrahedron 2005, 61, 7774.
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Retrosynthetic analysisRetrosynthetic analysis of of calvine and 2-epicalvinecalvine and 2-epicalvine
NC5H11
OO
NHC5H11
OHOTsC5H11
(Epi)calvine
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RRacemic total synthesisacemic total synthesis of calvine and 2- of calvine and 2-epicalvineepicalvine
a) Preparation of the substrate for the Pd(II)-catalysed aminocarbonylation
The identical sequence on analogous compounds: A. Fürstner, K. Langemann: Synthesis 1997, 792.
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RRacemic total synthesisacemic total synthesis of calvine and 2-epicalvine of calvine and 2-epicalvine
b) Finalisation - Pd(II)-catalysed carbonylation of rac-aminoalkenitol
NC5H11
OO
NHC5H11
OH
CO (balloon)0.1 eq. PdCl22 eq. CuCl2
2 eq. AcONadioxane, 40°C
7 hrs, 55%rac-calvine rac-2-epicalvine
NC5H11
OO
+
rac-aminoalkenitol (2.2 : 1)
26% total yield over 5 steps
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ConclusionsConclusions
• Intramolecular Pd(II)-catalysed methoxycarbonylation and/orIntramolecular Pd(II)-catalysed methoxycarbonylation and/or chlorocyclisation of aminoalkenes represents a novel synthetic approachchlorocyclisation of aminoalkenes represents a novel synthetic approach to (poly)substituted piperidinesto (poly)substituted piperidines
• Such structures may well serve as key building blocks for the totalSuch structures may well serve as key building blocks for the total syntheses of various nitrogen-containing natural productssyntheses of various nitrogen-containing natural products
• Both transformations were developed intoBoth transformations were developed into effectiveeffective synthetic methodsynthetic methodologiesologies that were successfully that were successfully emploemployyeded in the total synthesis of alkaloids as well in the total synthesis of alkaloids as well asas their unnatural analoguestheir unnatural analogues
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AcknowledgmentsAcknowledgments
Generous support Prof. Dr. Tibor GraczaCo-workers Ing. Kristína Csatayová
Katarína ReichováTechnical support Mária KrajčírováGC, MALDI Dr. Ivan ŠpánikHPLC Dr. Katarína HroboňováNMR Dr. Nadežda PrónayováIR Silvia MarkusováGrant APVT-20-000904
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Known Known precedentsprecedents of Pd(II)/CuCl of Pd(II)/CuCl22-catalysed-catalysedhalhaloaminocyclisationoaminocyclisation yielding 6-membered azacycles yielding 6-membered azacycles
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ReportsReports o onn Pd(II)/Cu Pd(II)/Cu(II)(II)--heterobimetallic complexesheterobimetallic complexes
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Proposed mechanismProposed mechanism of the Pd(II)-catalysed of the Pd(II)-catalysed carbonylationcarbonylation
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Observed interconversion of calvine and 2-Observed interconversion of calvine and 2-epicalvine in protic mediaepicalvine in protic media
But no epimerisation reported with:
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Formation of the undesired ketone side productFormation of the undesired ketone side product
viavia MPV-type mechanism MPV-type mechanism
B. G. Kovalev et al.: Zh. Org. Khim. 1975, 11, 1183.
The only literature precedent: