The total synthesis of (+)-ryanodol. Part II. Model studies for rings B and C of (+)-anhydroryanodol. Preparation of a key pentacyclic intermediate

1990 ◽  
Vol 68 (1) ◽  
pp. 127-152 ◽  
Author(s):  
Pierre Deslongchamps ◽  
André Bélanger ◽  
Daniel J. F. Berney ◽  
Hans-Juerg Borschberg ◽  
Robert Brousseau ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Optically Active ◽  
Vinyl Ketone ◽  
Starting Material ◽  
The Other ◽  
Model Studies

This paper reports several model studies that were necessary for the rational conception of a simple four-step synthesis (6 + (S)-74 → 81a–b → 83 [Formula: see text] 87 → 89) (Scheme 11) of the carbonate derivative 89 of the optically active pentacyclic dihydroxy ketoaldehyde 87, an important key intermediate for the synthesis of (+)-ryanodol (5). The optically active vinyl ketone (S)-74 that was used as starting material was prepared in four steps from d-carvone ((S)-94) (Scheme 13). The preparation of the other starting material, the o-spirolactone dienone 6, was reported in Part I. Keywords: strategy, synthesis, ryanodol, key intermediate, diterpene.

Synthesis of the spirosesquiterpene (−)-acorenone and related cyclopentanoid monoterpenes

1978 ◽  
Vol 56 (12) ◽  
pp. 1628-1633 ◽  
Author(s):  
Gordon L. Lange ◽  
Eli E. Neidert ◽  
Will J. Orrom ◽  
David J. Wallace
Keyword(s):  
Acetic Acid ◽  
Total Synthesis ◽  
Absolute Configuration ◽  
Optically Active ◽  
Starting Material ◽  
Critical Step ◽  
Naturally Occurring ◽  
Toluenesulfonic Acid ◽  
Methylmagnesium Iodide ◽  
Cyclopentanoid Monoterpenes

The first total synthesis of the spirosesquiterpene (−)-acorenone (1) is described. The critical step involves a spiroannelation of the enamine of aldehyde 11 with 1-methoxy-3-buten-2-one (16) in the presence of acetic acid to give ketone 17. Reaction of 17 with methylmagnesium iodide followed by treatment of the resultant alcohol 18 with p-toluenesulfonic acid in refluxing benzene leads directly to 1 in good overall yield. As the starting material for the preparation of the cyclopentanoid aldehyde 11 was (+)-limonene the final product is optically active and thus the absolute configuration of naturally occurring (−)-acorenone (1) is established. The preparation of a number of other optically active cyclopentanoid monoterpenes (4 and 13) is also described.

Total synthesis of anisomycin

1969 ◽  
Vol 47 (13) ◽  
pp. 2421-2424 ◽  
Author(s):  
C. M. Wong ◽  
J. Buccini ◽  
I. Chang ◽  
J. Te Raa ◽  
R. Schwenk
Keyword(s):  
Acetic Anhydride ◽  
Total Synthesis ◽  
Tartaric Acid ◽  
Benzyl Bromide ◽  
Starting Material ◽  
The Other ◽  
Hydrogenation Condition ◽  
Synthetic Approaches

Two synthetic approaches to anisomycin had been studied. One approach used 2R 3R tartaric acid as starting material and was successfully converted to the hydrochlorides of (+)-anisomycin (22) in an overall yield of about 5% and (−)-anisomycin (1) in about 1% yield. Liberation of the free bases gave (+)-anisomycin and (−)-anisomycin. The other approach started with α-anisyl pyrrole and was converted to (±)-deacetyl anisomycin 2. The conversion of 2 to anisomycin was done by treating natural deacetyl anisomycin with benzyl bromide to give 9. Conversion of 8 and 9 to (+)-anisomycin and (−)-anisomycin was done by selective acetylation with acetic anhydride and debenzylation under hydrogenation condition.

Recent advances on the synthesis of the antidepressant Paroxetine

2020 ◽  
Vol 27 ◽  
Author(s):  
Joana Santos ◽  
M. Fernanda Proença ◽  
Ana Joao Rodrigues ◽  
Patricia Patrício ◽  
H. Sofia Domingues
Keyword(s):  
Total Synthesis ◽  
Neurological Disorders ◽  
Serotonin Reuptake ◽  
Potent Inhibitor ◽  
Starting Material ◽  
Substitution Pattern ◽  
Biological Probes ◽  
Recent Advances ◽  
Treatment Of Depression ◽  
Made In

: Paroxetine is a potent inhibitor of serotonin reuptake and is widely prescribed for the treatment of depression and other neurological disorders. The synthesis of paroxetine and the possibility to prepare derivatives with a specific substitution pattern that may allow their use as biological probes, is an attractive topic especially for medicinal chemists engaged in neurosciences research. Considering the extensive work that was developed in the last decade on the total synthesis of paroxetine, this review summarizes the most important contributions in this field, organized according to the reagent that was used as starting material. Most of the methods allowed to prepare paroxetine in 4-9 steps with an overall yield of 9-66%. Despite the progress made in this area, there is still room for improvement, searching for new eco-friendly and sustainable synthetic alternatives.

Studies Directed Towards the Total Synthesis of Anticapsin and Related Compounds. IV. Competitive Reaction of Amino and Carboxy Substituents in the Halohydrination of 2-Aminobicyclo[2.2.2]oct-5-ene-2-carboxylic Acid Derivatives

1994 ◽  
Vol 47 (12) ◽  
pp. 2221 ◽  
Author(s):  
MJ Crossley ◽  
SR Davies ◽  
TW Hambley
Keyword(s):  
Total Synthesis ◽  
The Other ◽  
X Ray Diffraction ◽  
Amino Groups ◽  
Competitive Reaction ◽  
Trimethylsilyl Group ◽  
X Ray ◽  
Tricyclic Compounds ◽  
Tricyclic Compound ◽  
Related Compounds

Bromohydrination of benzyl (1RS,2SR,4SR)-2-benzyloxycarbonylamino-1-trimethylsilyloxy-bicyclo[2.2.2]oct-5-ene-2-carboxylate (6a) and the (1RS,2RS,4SR)- diastereomer (6b) with N- bromoacetamide in aqueous dioxan has been investigated. These reactions are highly regio-and stereo-selective and give the corresponding bromohydrins (9a) and (9b), but in moderate to low yield. These bromohydrins have the necessary stereochemistry for conversion into anticapsin. The other products from the reaction are tricyclic compounds formed by capture of the anti- bromonium cation intermediates or resultant bromohydrins by interaction with the proximal protected carboxy and amino groups within the molecules. Thus the carbolactone (11) is formed from the endo -adduct (6a), and the carbonimidic acid derivative (12) and the cyclic urethane (13) are formed from the exo-adduct (6b). Cleavage of the trimethylsilyl group from the tricyclic compound (12) gives benzyl (1RS,2RS,3RS,7RS,8RS)-5-benzyloxy-2-bromo-8-hydroxy-4-oxa-6-azatricyclo[5.3.1.03,8]undec-5-ene-7-carboxylate(14), the structure of which was determined by X-ray diffraction methods and refined to a residual of 0.035 for 1549 independent observed reflections. The crystals of (14) are monoclinic, P21/c, a 12.954(3), b 6.197(3), c 26.784(7) Ǻ, β 95.33(2)°, Z 4. Reactions attempting to generate iodohydrins from the alkenes (6) were also highly regioselective and gave detrimethylsilylated iodo analogues of (11) and (13).

Synthesis of Optically Active Hydroxyalkyl Cycloheptatrienes: A Key Step in the Total Synthesis of 6,11-Methylene-LXB4

Synlett ◽  
2020 ◽  
Vol 32 (01) ◽  
pp. 45-50
Author(s):  
Udo Nubbemeyer ◽  
Analuisa Nava ◽  
Lukas Trippe ◽  
Andrea Frank ◽  
Lars Andernach ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Total Synthesis ◽  
Structure Elucidation ◽  
Butyl Ester ◽  
Optically Active ◽  
Chiral Hplc ◽  
Reaction Conditions ◽  
Acid Product ◽  
Tert Butyl ◽  
Nabh4 Reduction

AbstractStarting from methyl cycloheptatrienyl-1-carboxylate, 6-acylation was successfully achieved employing glutaryl chloride in the presence of AlCl3 under controlled reaction conditions to furnish keto carboxylic acid product. After protection of this keto carboxylic acid as tert-butyl ester, reagent-controlled enantioselective reductions delivered configuration-defined methyl-6-hydroxylalkyl cycloheptatriene-1-carboxylates with up to 80% ee. Whereas simple NaBH4 reduction of the keto carboxylic acid and subsequent lactonization afforded a methyl-6-tetrahydropyranonyl cycloheptatriene-1-carboxylate. Resolution using chiral HPLC delivered the product enantiomers with up to >99% ee Finally, ECD analyses enabled structure elucidation. The products are used as key intermediates in enantioselective 6,11-methylene-lipoxin B4 syntheses.

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