Total synthesis of the stemodane-type diterpenoids (±)-stemodin and (±)-maritimol. Formal total synthesis of (±)-stemodinone and (±)-2-desoxystemodinone

1985 ◽  
Vol 63 (12) ◽  
pp. 3418-3432 ◽  
Author(s):  
Edward Piers ◽  
Brian F. Abeysekera ◽  
David J. Herbert ◽  
Ian D. Suckling
Keyword(s):  
Total Synthesis ◽  
Room Temperature ◽  
The Other ◽  
Subsequent Reaction ◽  
Total Syntheses ◽  
Keto Esters ◽  
Other Hand ◽  
Synthetic Intermediates ◽  
Separation Of Mixtures ◽  
Hydrolysis Of

Total syntheses of the stemodane-type diterpenoids (±)-stemodin (2) and (±)-maritimol (4), as well as formal total syntheses of (±)-stemodinone (3) and (±)-2-desoxystemodinone (5), are described. The known ketol 12 was converted into the tricyclic enone 7. Photoaddition of aliène to 7 gave (96%) a mixture of the photoadducts 20–23 (40:51:6:3, respectively). Ozonolysis of 20, followed by treatment of the resultant dione 24 with MeONa–MeOH (room temperature, 2.5 h), provided the keto ester 26 (94%). Subjection of 21 to an identical sequence of reactions gave (86%) the same product 26. On the other hand, when the dione 25 was treated with MeONa–MeOH under much milder conditions (0 °C, 5 min), the isomeric keto esters 27 (39%) and 28 (33%) were produced. Both 27 and 28, upon reaction with MeONa–MeOH at room temperature, were converted efficiently into 26. Reduction (NaBH4 or Lisec-Bu3BH) of 26 provided separable mixtures of the ester alcohol 32 and the lactone 33, which could be transformed readily into the dimesylates 35 and 39, respectively. Reaction of 35 and 39 with NaCN in warm hexamethylphosphoramide afforded the dinitriles 37 and 40, both of which, upon treatment with t-BuOK in refluxing t-BuOH, produced the sameenaminonitrile 41. Acid hydrolysis of 41 provided the dione 42. Preparatively, compound 26 could be transformed conveniently into the dione 42 (52% overall yield) without separation of mixtures of isomeric synthetic intermediates. Treatment (CH2Cl2, −95 °C) of 42 with Mc3Sil–Et3N, followed by oxidation of the resultant products 46 and 47 with Pd(OAc)2 in acetonitrile, gave the bis enones 48 (67%) and 49 (19%). Compound 48 was converted into the dione 52 which, upon reaction with (i-PrO)3 TiMe in ether, provided an 86:14 mixture of the keto alcohols 53 and 54 (63% from 48). Reduction (NaBH4) of 53 afforded (±)-maritimol (4). On the other hand, conversion of the 86:14 mixture of 53 and 54 into the p-toluenesulfonylhydrazones 55 and subsequent reaction of 55 with NaH in refluxing toluene gave the alkene alcohols 56 (58%) and 57 (12%). Hydroboration–oxidation (9-BBN, refluxing tetrahydrofuran; NaOH, H2O2) of 56 afforded (88%) (±)-stemodin (2).

Synthesis of functionalized bicyclo[3.2.1]octa-2,6-dienes by thermal rearrangement of substituted 6-exo-(1-alkenyl)bicyclo[3.1.0]hex-2-ene systems

1987 ◽  
Vol 65 (3) ◽  
pp. 670-682 ◽  
Author(s):  
Edward Piers ◽  
Grace L. Jung ◽  
Edward H. Ruediger
Keyword(s):  
Acid Hydrolysis ◽  
The Other ◽  
Silyl Ether ◽  
Thermal Rearrangement ◽  
Enol Ether ◽  
Silyl Ethers ◽  
Keto Esters ◽  
Other Hand ◽  
Enol Silyl Ethers ◽  
Hydrolysis Of

Thermolysis of each of the enol silyl ethers 31–35 affords, cleanly and efficiently, the bicyclo[3.2.1]octadienes 36–40, respectively. Similarly, thermal rearrangement of the enol silyl ether 50 provides the diene 51. Hydrolysis of 36, 37, and 39, and decarbomethoxylation of the resultant keto esters 41, 42, and 44, gives the ketones 46–48, respectively. The ketone 46 is also obtained by acid hydrolysis of 51. Conversion of 6-methyl-1-hepten-4-yn-3-ol (56) into the enol ether 63 is described. Thermolysis of 63 gives 64, which, upon acid hydrolysis, affords 65. Thermolysis of the enones 68 and 69 produces the bicyclic dienones 70 and 71, respectively. On the other hand, thermolysis of 73 and 74, derived from the enone 69, provides the C-8 exo substituted bicyclo[3.2.1]octa-2,6-dienes 75 and 76, which are transformed smoothly, by acid hydrolysis, into the ketones 77 and 78, respectively.

scholarly journals Synthesis of spiro[dihydropyridine-oxindoles] via three-component reaction of arylamine, isatin and cyclopentane-1,3-dione

2013 ◽  
Vol 9 ◽  
pp. 8-14 ◽  
Author(s):  
Yan Sun ◽  
Jing Sun ◽  
Chao-Guo Yan
Keyword(s):  
Acetic Acid ◽  
Reaction Mechanism ◽  
Room Temperature ◽  
The Other ◽  
Other Hand ◽  
Three Component Reaction ◽  
High Yields

A fast and convenient protocol for the synthesis of novel spiro[dihydropyridine-oxindole] derivatives in satisfactory yields was developed by the three-component reactions of arylamine, isatin and cyclopentane-1,3-dione in acetic acid at room temperature. On the other hand the condensation of isatin with two equivalents of cyclopentane-1,3-dione gave 3,3-bis(2-hydroxy-5-oxo-cyclopent-1-enyl)oxindole in high yields. The reaction mechanism and substrate scope of this novel reaction is briefly discussed.

Diversification of α–Ketoamides via Transamidation Reactions with Alkyl and Benzyl Amines at Room Temperature

2021 ◽  
Author(s):  
Shweta Singh ◽  
Sureshbabu Popuri ◽  
Qazi Mohammad Junaid ◽  
Sabiah Shahul Hameed ◽  
Jeyakumar Kandasamy
Keyword(s):  
Room Temperature ◽  
The Other ◽  
Alkyl Amines ◽  
Other Hand ◽  
Wide Range

A wide range of N-tosyl α–ketoamides underwent transamidation with various alkyl amines in the absence of catalyst, base, or additives. On the other hand, transamidation in N-Boc α–ketoamides is achieved...

Letters to the Editor

PEDIATRICS ◽  
1973 ◽  
Vol 52 (2) ◽  
pp. 309-309
Author(s):  
C. Warren Bierman
Keyword(s):  
Room Temperature ◽  
Skin Testing ◽  
The Other ◽  
Letters To The Editor ◽  
Other Hand ◽  
Number Of Patients ◽  
Testing Solution

Dr. Bergner is quite correct in pointing out that skin testing with a freshly prepared penicillin solution will select out only about 30% of patients who are anaphylacticly sensitive to penicillin.1 On the other hand, the use of a sterile solution of benzylpenicillin diluted with alkaline buffered saline (pH 7.6) and permitted to stand at room temperature for at least two weeks appreciably increases the number of patients so detected.2 We would agree that the availability of a penicilloyl polylysine (PPL) testing solution and a stabilized minor determinent mixture (MDM) would greatly enhance the armamentarium of the clinician to detect anaphylactic sensitivity to penicillin.3

PRECOCIOUS TERMINATION OF “OBLIGATORY” DIAPAUSE IN FIELD-COLLECTED PUPAE OF ANTHERAEA POLYPHEMUS

1968 ◽  
Vol 100 (2) ◽  
pp. 134-139 ◽  
Author(s):  
A. Mansingh ◽  
B. N. Smallman
Keyword(s):  
Adult Development ◽  
Room Temperature ◽  
The Other ◽  
Mortality Factor ◽  
Natural Mortality ◽  
Antheraea Polyphemus ◽  
Other Hand ◽  
Heavy Mortality

AbstractAntheraea polyphemus Cramer pupae, collected in early August, were found to maintain adult development at room temperature and natural daylength of late August and early September. These pupae had almost no coldhardiness, and heavy mortality occurred in the group of pupae stored at 6 °C. On the other hand, the pupae of A. polyphemus collected in late September were in diapause and were perfectly coldhardy. The possible relationship between the date of pupation and the incidence of diapause, and its significance as a natural mortality factor, is discussed.

Electrochemical Hydriding of Mg-Based Alloys

2011 ◽  
Vol 312-315 ◽  
pp. 882-887
Author(s):  
Dalibor Vojtěch ◽  
Vítězslav Knotek ◽  
Pavel Novák
Keyword(s):  
Hydrogen Storage ◽  
High Temperatures ◽  
Room Temperature ◽  
Hydrogen Atmosphere ◽  
The Other ◽  
High Hydrogen ◽  
Hydrogen Saturation ◽  
Other Hand ◽  
Mechanism And Kinetics ◽  
Storage Methods

Mg-based alloys are prospective materials for reversible hydrogen storage in the form of metallic hydrides. Usually, hydrogen saturation is carried out at high temperatures and high hydrogen pressures. This is the reason for the high cost of metallic hydrides in comparison with other hydrogen storage methods. Electrochemical hydriding, on the other hand, can be realized at room temperature. Moreover, this process does not need any hydrogen atmosphere. In the presented work, electrochemical hydriding of several Mg-Ni-Mm-based alloys (Mm = mishmetal) is performed. Hydriding efficiency, mechanism and kinetics are described. It is shown that the additions of Ni, Mm and the formation of eutectic structures support hydriding of alloys.

Synthesis and antibacterial activity of some 1-(2-propynyl) and 1-propadienyl derivatives of 1,4-dihydro-4-oxoquinoline-3-carboxylic acids and similar heterocycles

1991 ◽  
Vol 56 (2) ◽  
pp. 439-448 ◽  
Author(s):  
Stanislav Rádl ◽  
Lenka Kovářová ◽  
Jiří Holoubek
Keyword(s):  
Antibacterial Activity ◽  
Dimethyl Sulfoxide ◽  
Carboxylic Acids ◽  
Potassium Carbonate ◽  
Potassium Hydroxide ◽  
Room Temperature ◽  
Ethyl Esters ◽  
The Other ◽  
Other Hand ◽  
Derivatives Of

N-Alkylation of IIIa, IIIb, IIId - IIIf and 9-acridanone with 3-bromopropyne in dimethyl sulfoxide in the presence of potassium carbonate yielded N-(2-propynyl) derivatives IVa - IVe and VIa, respectively. Ethyl esters IVa, IVb, and IVe were hydrolyzed to IVf - IVh, respectively. Compounds IVf, IVg, IVctreated with bases yielded N-propadienyl derivatives Va - Vc. On the other hand 2-substituted compounds IVd and IVh did not change under the same conditions. Compound VIa treated with powdered potassium hydroxide in dimethyl sulfoxide at room temperature yielded N-(1-propynyl) derivative VII.

scholarly journals ATP-dependent structural changes of the outer dynein arm in Tetrahymena cilia: a freeze-etch replica study.

1983 ◽  
Vol 96 (5) ◽  
pp. 1480-1485 ◽  
Author(s):  
S Tsukita ◽  
S Tsukita ◽  
J Usukura ◽  
H Ishikawa
Keyword(s):  
Structural Changes ◽  
Lateral View ◽  
The Other ◽  
Replica Technique ◽  
Other Hand ◽  
Dynein Arms ◽  
Hydrolysis Of

With the rapid-freeze, deep-etch replica technique, the structural conformations of outer dynein arms in demembranated cilia from Tetrahymena were analyzed under two different conditions, i.e., in the absence of ATP and in the presence of ATP and vanadate. In the absence of ATP, the lateral view of axonemes was characterized by the egg-shaped outer dynein arms, which showed a slightly baseward tilt with a mean inclination of 11.1 degrees +/- 3.4 degrees SD from the perpendicular to the doublet microtubules. On the other hand, in the presence of 1 mM ATP and 100 microM vanadate, the outer arms were extended and slender and showed an increased baseward tilt with a mean inclination of 31.6 degrees +/- 4.9 degrees SD. In ATP-activated axonemes, these two types of arms coexisted, each type occurring in groups along one row of outer arms. These findings strongly suggest that the interdoublet sliding is caused by dynamic structural changes of dynein arms that follow the hydrolysis of ATP.

STEROIDS AND RELATED PRODUCTS: VII. THE SYNTHESIS OF 17α-METHYLCORTICOSTERONE

1957 ◽  
Vol 35 (2) ◽  
pp. 131-140 ◽  
Author(s):  
Ch. R. Engel
Keyword(s):  
Ethylene Glycol ◽  
Biologically Active ◽  
The Other ◽  
Keto Group ◽  
Methyl Group ◽  
Other Hand ◽  
Hydrolysis Of

The synthesis of 17α-methylcorticosterone, a new biologically active homologue of corticosterone and analogue of cortisol, is described. In the course of the work it was observed that the 17-methyl group greatly impeded both the formation and the hydrolysis of a 20-ketal. On the other hand, evidence was obtained that the 11-keto group is not completely unreactive towards ethylene glycol, in the presence of p-toluenesulphonic acid.

scholarly journals First result of tartaric stabilization by adding mannoproteins (Mannostab™)

OENO One ◽  
1997 ◽  
Vol 31 (1) ◽  
pp. 23 ◽  
Author(s):  
Virginie Moine-Ledoux ◽  
A. Perrin ◽  
I. Paladin ◽  
Denis Dubourdieu
Keyword(s):  
Cell Wall ◽  
Enzymatic Hydrolysis ◽  
New Product ◽  
Model Solution ◽  
The Other ◽  
Inhibitor Activity ◽  
Commercial Preparation ◽  
Other Hand ◽  
Crystallization Inhibitor ◽  
Hydrolysis Of

<p style="text-align: justify;">Some mannoproteins which are extracted by enzymatic hydrolysis of yeast's cell wall with the aid of commercial preparation composed with beta-glucanases (Glucanex™) inhihits the tartaric acid's salt breakdown in model solution as well as in wines for an addition between 10 and 25 g/hl. On the other hand, heat extracted mannoproteins arc inactive on the tartaric precipitation stabilization. Furthermore, the crystallization inhibitor activity of the enzymatic extracted mannoproteins is due to the presence of sharply glycosylated mannoproteins of mediummolecular weight (30 to 50 kda) which are not heat extracted. That is why the heat extracted mannoproteins are inactive. The enzymatic extracted mannoproteins are produced at a pilot plan. This preparation (Mannostab™), soluble in wines, colourless and without any flavour, stabilize with the same efficiency than a freeze treatment and this effective live is superior to the metatartric acid. Moreover, the necessary steps were been taked to permit experimentally this new product : Mannostab™</p>

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