Synthetic Studies Towards the and Ergot Alkaloids

N O H H Me O O N O O H H N H

N H

Anthony Cuzzupe University of Pittsburgh Wipf Research Group November 12, 2005

Anthony Cuzzupe @ Wipf Group 1 11/12/2005 Presentation Outline

PART 1: Stemona Alkaloids - Stemona & historical uses - Stemona alkaloids: isolation, classification, biological properties, etc - Selected previous total syntheses and Wipf group work - Current approaches

PART 2: Ergot Alkaloids - Ergot & history of ergotism - Ergot alkaloids: isolation, classification, biological properties, etc - Current approaches

Anthony Cuzzupe @ Wipf Group 2 11/12/2005 PART 1: Stemona Alkaloids

Anthony Cuzzupe @ Wipf Group 3 11/12/2005 Family:

 A family made up of three genera:

1. Stemona - About 25 species, occurring from southern Asia and Malaysia to northern Australia

2. Croomia - Three species from Atlantic North America and Japan

3. Stichoneuron - Two species from eastern Asia Nat. Prod. Rep. 2000, 17, 117

 Stemona plants occur as subshrubs or twining herbs, mostly with perennial tuberous roots

Stemona Tuberosa Stemona Sessifolia

Stemona Sessifolia www.bihrmann.com www.bihrmann.com www.bihrmann.com

Anthony Cuzzupe @ Wipf Group 4 11/12/2005 Stemonaceae: Historical Uses

 Extracts from plants of the Stemonaceae family (Stemona and Croomia genera) have been used for centuries in Eastern folk medicines

 Example: Extracts from the tuberous roots of Stemona Tuberosa, Stemona Japonica and Stemona Sessifolia have been used by the Chinese and Japanese for:

- Respiratory diseases such as tuberculosis and bronchitis - Antihelmintics in humans and cattle

- Insecticides J. Agric. Food. Chem. 2002, 50, 6383

www.clgc.rdi.ku.ac.th/research/stemona/stemona www.bihrmann.com

Anthony Cuzzupe @ Wipf Group 5 11/12/2005 Stemona Alkaloids: Isolation & Structural Elucidation

Phytochemical studies have been limited to only eight species, mostly from Stemona

Progress hampered by use of incorrectly identified material - caused by popular use of tuberous roots from different species sold on the market under the same names, eg. “Bai Bu” in and “Bach Bo” in Vietnam

Tuberostemonine was the first Stemona O alkaloid to be isolated in 1934 by Suzuki H H O O O H N Structure of tuberostemonine was determined H by the combined efforts of a number of groups Tuberostemonine in the 1960’s using various methods: NMR, MS, X-ray and chemical analysis

Since then more than 42 Stemona alkaloids have been isolated, mostly by Ren-sheng Xu and coworkers in the 80’s. The various structures were determined by X-ray analysis, spectroscopic methods and/or chemical studies

Anthony Cuzzupe @ Wipf Group 6 11/12/2005 Structural Classification of Stemona Alkaloids

Large majority of the Stemona alkaloids are structurally characterized by the presence of a pyrrolo[1,2-a]azepine core 9 8 9a 1 7 2 N 3 6 5

Each member of the Stemona alkaloid family can be classified into five main groups according to their structural features - the name of each group being the name of the simplest member:

O Me Me O H H O O O OMe Me O N O O Me Me H H OH N H O Me O Me Et Stemoamide O H H N O O H N H Stemonamine O H H N O Stenine Tuberostemospironine Parvistemoline

A sixth miscellaneous group of compounds also exist where each member lacks the common azepine ring system Nat. Prod. Rep. 2000, 17, 117

Anthony Cuzzupe @ Wipf Group 7 11/12/2005 Structural Classification of Stemona Alkaloids

Stenine group Stenine Parvistemoline group Tuberostemonine Parvistemoline Tuberostemonine A Parvistemonine Tuberostemonol Didehydroparvistemonine Didehydrotuberostemonine Bisdehydroneotuberostemonine Neotuberostemonine

Stemoamide group Stemonamine group Stemoamide Stemonamine Stemonine Isostemonamine Neostemonine Stemonamide Bisdehydroneostemonine Isostemonamide Protostemonine Maistemonine Didehydroprotostemonin Oxymaistemonine e Isoprotostemonine Tuberostemoamide Tuberostemospironine group Miscellaneous group Stemoninine Tuberostemospironine Stemofoline Croomine Oxystemofoline Stemospironine Methoxystemofoline Stemotinine Parvistemoninine Isostemotinine Parvistemoninol Stemonidine Tuberostemonone Didehydrocroomine Tuberostemoninol Parvistemoamide

Anthony Cuzzupe @ Wipf Group 8 11/12/2005 Biological Studies on Stemona Alkaloids

Limited evidence that any pure Stemona alkaloid has therapeutic potential in humans

Tuberostemonine has antihelmintic activity

Tuberostemonine found to be a glutamate inhibitor (blocks neuromuscular transmission) in crayfish Brain Res. 1985, 334, 33

Tuberostemonine has potent antifeeding activity J. Agric. Food. Chem. 2002, 50, 6383

Stemonine, stemospironine and stemofoline have some insecticidal activity, eg. active against Bombyx mori (silkworm larvae) Agric. Biol. Chem. 1978, 42, 457

Anthony Cuzzupe @ Wipf Group 9 11/12/2005 (+)-Croomine (Williams)

CO2Me 1. BnO(CH2)4MgBr, OH CuBr•DMS, 95% O 1. Swern CO2Me H O 2. DIBAL-H, 98% 2. Ph P=CHCO Me H MEMO 3 2 OBn 3. SAE, 83% MEMO 89% OBn MEMO

OBz 1. LiBH4, 81% 1. BF3•OEt2, 81% O 2. LiOH, 97% 2. Rh/Al2O3, H2, 62% O OBz N N3 3. BzCl, 97% 3 3. Swern, then 4. LiN , DMPU, 94% HO OBn 3 Ph3P MEMO OBn OBz 74%

1. aq. HBF , 72% 1. BCl3 then MeOH, 77% 4 H 2. LiOH, 86% 2. Swern, 92% CO Me CO Me N 2 A NH 2 3. Jone's Reagent O 3 3. PPh (Staudinger then O O 3 O B then CH N , 78% intramolec Wittig) 2 2 OBn then NaBH4, 90%

H I2, CH2Cl2/Et2O H N O O 26 Steps, ~0.5% Overall 25% O H O (+)-Croomine J. Am. Chem. Soc. 1989, 111, 1923

Anthony Cuzzupe @ Wipf Group 10 11/12/2005 (±)-Stenine (Hart & Chen)

H H OH IMDA 1. MsCl, NEt3 O O 67% NHCO Me 2. MeLi H 2 O O 94%

OAc

H H H 1. Jones reagent 2. Iodolactonization 1. NaBH N 4 N N O HO 3. DBU H CO Me 2. TBSCl H H 2 CO2Me CO2Me 76% O Confirmed by X-ray OTBS OH

O

Me N 2 H MeC(OMe)2NMe2

xylene, ! N H 93%, 3 steps CO2Me (Eschenmoser-Claisen) OTBS

J. Org. Chem. 1990, 55, 6236

J. Org. Chem. 1993, 58, 3840

Anthony Cuzzupe @ Wipf Group 11 11/12/2005 (±)-Stenine (Hart & Chen)

O O O Me2N 1. I , THF/H O H 2 2 H O O H 2. SnBu3 N N N H AIBN, Tol, H CO2Me CO Me H CO Me 62% 2 2 OTBS OH EtO2C

O O

H H O 1. OsO , NaIO O 1. TMS-I 4 4 S 2. Tol, SH S N N 2. HS 85% O R

R = O Confirmed by X-ray Lawesson's Reagent R = S 84% (3 steps) O

O H W-2 Raney Ni

75% N J. Org. Chem. 1990, 55, 6236 )-Stenine (± J. Org. Chem. 1993, 58, 3840

25 Steps, 5% Overall

Anthony Cuzzupe @ Wipf Group 12 11/12/2005 (-)-Stemoamide (Jacobi)

1. NaH OEt 1. Swern O HO O MeO O N O N Cl N 2. (MeO)2P(O)CHN2 MeO H O MeO O O THF, tBuOK N 65% N N 2. TsOH, MeOH 56% (2 steps)

O O O LDA, MeI N Diethylbenzene N ! N MeO 32% O ! RDA MeO O MeO O N N

O O + H workup N NaBH4, NiCl2 N 10 7 Steps, 4.5% Overall 53% (with C10 epimerization) O O O O H 73% H (-)-Stemoamide

J. Am. Chem. Soc. 2000, 122, 4295

Anthony Cuzzupe @ Wipf Group 13 11/12/2005 Wipf Group Research

Efficient stereoselective preparation of the hydroindole ring system of the Stemona alkaloids by oxidative cyclization of tyrosine:

O H N OH R PhI(OAc)2 NaHCO3 CO2Me CO2H HO MeOH, rt O MeOH, rt O N H 68% 75% R R = Boc or Cbz R NH O

PhI(OAc)2

MeOH, NaHCO3, rt 54% ** Reaction has been sclaed to > 100 g Tetrahedron Lett. 1992, 33, 5477

Selectivity attributed to A1,3 - strain:

O O O O H E R OH HO R N N H H E H 1,3 A - Strain J. Am. Chem. Soc. 1995, 117, 11106

Anthony Cuzzupe @ Wipf Group 14 11/12/2005 Wipf Group Research

Oxidation of tyrosine - used for the synthesis of a variety of targets:

O O O H O O N O O

N OH H (-)-Stenine Functionalized aranorosin core O J. Am. Chem. Soc. 1995, 117, 11106 OH J. Org. Chem. 1993, 58, 1649

CO2Me O O N H Cbz Cbz N O H HO

O N H N H O O H NH O O NH HN OH N H O O OH NH2 Aeruginosin 298-A (-)-Tuberostemonine

HO Org. Lett. 2000, 2, 4213 J. Am. Chem. Soc. 2002, 124, 14848 J. Am. Chem. Soc. 2005, 127, 225

Anthony Cuzzupe @ Wipf Group 15 11/12/2005 Total Synthesis of (-)-Stenine (Wipf)

OH OBz H 1. Bz2O, NEt3 Pd2(dba)3•CHCl3 CO2Me CO2Me CO2Me 2. Luche reduction Bu P, HCO H/NEt O N HO N 3 2 3 HO N H H H Cbz 89% Cbz 68% Cbz

O

H Me N 2 H 1. TPAP, NMO 1. Luche reduction CO2Me N CO Me O 2. CH C(OMe) NMe 2 2. KHMDS H Cbz 3 2 2 N H HC=CH(CH2)3OTf (Eschenmoser-Claisen) Cbz 46% 77%

O O

Me2N H H 1. I2 O

2. SnBu3 N N AIBN H H Cbz Cbz 77% OTIPS OTIPS

J. Am. Chem. Soc. 1995, 117, 11106

Anthony Cuzzupe @ Wipf Group 16 11/12/2005 Total Synthesis of (-)-Stenine (Wipf)

O O O

H H O O H O 1. Pd(OH)2, H2 N N N H H 2. C6F5P(O)Ph2 Cbz Cbz O 71% OTIPS CO2H

O

H 1. Lawesson's reagent O 25 Steps, 2% Overall 2. Raney-Ni N 73%

(-)-Stenine

J. Am. Chem. Soc. 1995, 117, 11106

Anthony Cuzzupe @ Wipf Group 17 11/12/2005 Total Synthesis of (-)-Tuberostemonine (Wipf)

H H H Et3SiH, Pd(OAc)2 CO2Me CO Me CO2Me 2 N RO N NEt3 N O H TBSO H Cbz 90% H H TBSCl R = OH 97% R = TBS Ph

H H 1. Luche reduction, 71% 1. Ph-SH, NEt3 Ru Metathesis 2. TBSCl, 79% CO2Me 2. H2, (PPh3)3RhCl CO2Me N 92% O N 3. DBU O 3. (Me)(OMe)NH•HCl 81% Me2AlCl 94%

O H Me H N OMe Li O O TBSO N O TBSO N O O O 95% O

J. Am. Chem. Soc. 2002, 124, 14848 J. Am. Chem. Soc. 2005, 127, 225

Anthony Cuzzupe @ Wipf Group 18 11/12/2005 Total Synthesis of (-)-Tuberostemonine (Wipf)

H H CH C(OMe) NMe H 3 2 2 1. L-Selectride, 80% (Eschenmoser-Claisen) TBSO N O O O O HO N H O O 2. TsOH, MeOH, 70% 78%

O 1. PhSeCl, ACN/H2O, 67% O Me2N H SnPh3 H H 2. AIBN O H 70% N O H O 3. LDA, MeI, 76% N H O O

O 1. Ru alkene isomerization H 2. Ru Metathesis, ethylene O H 24 Steps, 1.4% Overall 3. H2, Pd/C N H O O 67% overall

(-)-Tuberostemonine

J. Am. Chem. Soc. 2002, 124, 14848 J. Am. Chem. Soc. 2005, 127, 225

Anthony Cuzzupe @ Wipf Group 19 11/12/2005 PART 2: Ergot Alkaloids

Anthony Cuzzupe @ Wipf Group 20 11/12/2005 Ergot: Claviceps purpurea

Ergot: Originates from an old French word “argot”, meaning “spur”

Ergot is a fungal disease of rye and other cereal crops - invades grain and replaces them with hard fungal bodies called sclerotia (resting body of a fungus)

Ergot fungal growth is suited to cool, damp climates - common in Europe, especially France and Germany

www.botany.hawaii.edu

Anthony Cuzzupe @ Wipf Group 21 11/12/2005 Ergotism/History

Ergotism is a disease which occurred frequently in the Middle Ages - caused by the ingestion of food made with grains infected with ergot, eg. bread

Two types of ergotism:

1. “Gangrenous” form: Intense burning pain in limbs and gangrene due to vasoconstrictive properties of ergot. In severe cases, limbs would become black and dry (mummify)

NOTE: Ergotism was also known as “Holy fire” or “St. Anthony’s fire”

abdellab.sunderland.ac.uk grandfinale.at.infoseek.co.jp

Anthony Cuzzupe @ Wipf Group 22 11/12/2005 Ergotism/History

2. “Convulsive” form: Sufferers could become delirious, lethargic, manic and have hallucinations with double vision due to neurotoxic properties of ergot. In extreme cases, epileptic-type seizures leading to death

Ergotism and witchcraft? Salem witchcraft trials of 1692 in North America may have been due to ergotism

www.uh.edu/ engines/epi1037.htm

The last reported European outbreak of ergotism occurred in 1951 in a French village

- caused more than 200 cases and 4 deaths Modern drug discovery, 1999, 2, 20-21, 23-24, 28, 31

Anthony Cuzzupe @ Wipf Group 23 11/12/2005 Ergot Alkaloids

 The first ergot alkaloid to be isolated from sclerotia of the ergot fungus was ergotamine in

1918 by Stoll Stoll, A.: Swiss patent 79879 (1918); German patent 357272 (1922)

 The natural ergot alkaloids (>40) contain either lysergic acid (pharmacologically active, name ends with -ine) or isolysergic acid (pharmacologically inactive, name ends with -inine) as the parent structure

CO2H CO2H H N H N N N H H Me Me Chem. Rev. 1950, 47. 197 Lysergic acid Isolysergic acid

 The ergot alkaloids are classified into three main groups:

1. Clavine type - Simplest members considered as precursors to the other groups of ergot alkaloids in the biogenetic pathway

2. Water-soluble lysergic acid type: Are often amide derivatives of lysergic and isolysergic acids

3. Water-insoluble lysergic acid type: Are mainly peptide derivatives of lysergic and isolysergic acids The Lancet Neurology, 2003, 2, 429

Anthony Cuzzupe @ Wipf Group 24 11/12/2005 Biological activity

 The ergot alkaloids possess a wide spectrum of biological activity - act on the CNS

 Derivatives of lysergic acid have affinities for the receptors of the neurotransmitters noradrenaline, dopamine and seratonin - possibly due to structural analogy between the ergoline ring system and these neurotransmitters

 They may act as agonists, antagonists or play a dual role as partial-agonist and antagonist

COR

OH OH

N NH2 NH2 NH2 CH3 OH HO HN OH OH NH Lysergic acid derivative Noradrenaline Dopamine Serotonin

Appl. Microbiol. Biotechnol. 2001, 57, 593

Anthony Cuzzupe @ Wipf Group 25 11/12/2005 Ergot alkaloids - examples and uses

HO HO O O N N OH N N O O HN HN O HN O Me Me Ph Me O N N O N H O H H

Br N N N Me H H Ergotamine 2-Bromo-!-ergokryptine Methysergide Migraine relief Semisynthetic Semisynthetic - anti-Parkinson's - Migraine relief - reduce lactation in women

OH HN N Me Me O N N H O H

N N H H Ergonovine Lysergic acid diethylamide (LSD) - Induces labour (oxytocic) Synthetic derivative of lysergic acid - Decrease excessive uterine - Powerful hallucinogen bleeding post-childbirth

Anthony Cuzzupe @ Wipf Group 26 11/12/2005 Acknowledgements

Prof. Peter Wipf Dr. David Mareska Dr. Steven Geib (X - Ray) Wipf Group Members (past & present)

Anthony Cuzzupe @ Wipf Group 27 11/12/2005