Rearrangements and Oxidations of Tricarbocyclic Diterpenes<sup>1</sup>

Wenkert, Ernest; Jackson, B.

doi:10.1021/ja01534a054

Cited by 56 publications

(23 citation statements)

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“…Oxo-7-methoxy-4aci-methyE-I, 2,3,4,4a,9,10, IOa-octahydvo -lOaa-$henanthrcn (23 4 . -9,lO-l)ioxo-l/$, 4aa-dimethyl-l,2, 3,4,4a, 9,70,70a- ,4aa-dinzethyl-l, 2,3,4,4a, 9-hexahydrophenanthrenl a -carbonsauremethylester (25) I s , 4aor-Dimethyl-l,2,3,4, da, 9,10, IOa- Oxo-l~,4~-damethyl-l, 2,3,4,4a, 9,10,70a-octahydro-l0a~-~henanthren-7a-carbonsduremethylester (27 , 4aa-dimethyl-I, 2,3,4,4a, 9,10, IOa-octahydro-IOat9- Hydroxy-Ib, 4aa-dimethyl-I, 2,3,4, 4a, 9,70, IOa-octahydro-IOa~-fihenanthren-la-carbonsauremethylester (30 -lp, 4aa-dimethyl-I, 2,3,4, 4aa,9, 10, IOa-octahydro-I0a8-fihenanthven-la-cavbonsauvemethylester (31). 570 mg 30 wurden analog zu 7 + 8 methyliert (2,s g K,CO,, 65 ml Aceton, 1 ml Dimethylsulfat), wobei 555 mg Kristalle erhalten wurden, die 2mal umkristallisiert bei 91" schmolzcn.…”

Section: Experimenteller Teilunclassified

“…und ihrer Derivate zu Desisopropylverbindungen vom Typus 2 (Schema I ) . Da die beziiglich 2 in gegen 50% Ausbeute ablaufende Keaktion unter Konfigurationsumkehrung an der angularen Methylgruppe von 1 erfolgt6), muss es sich bei 2, gemass den Autoren [26][27][28], um das Produkt einer zweifachen Friedel-Crafts-Spaltung und einer anscliliessenden Friedel-Crafts-Kondensation handeln. Dabei wird die Isopropylgruppe durch Wasserstoff ersetzt, der B-Ring des Abietinsaure-Geriistes intermediar geoffnet und unter Inversion der angularen Methylgruppe wiederum geschlossen.…”

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Steroide und Sexualhormone. 249. Mitteilung [1]. Zur Umwandlung von Dehydroabietinsäure in 14α‐Methylsteroide I Die Partialsynthese von 5‐Methoxy‐17‐oxo‐14α‐methyl‐Δ^{5, 7, 9}‐des‐A‐östratrien

Wirthlin

Wehrli

Jeger

1974

Helvetica Chimica Acta

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Section: Experimenteller Teilunclassified

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Steroide und Sexualhormone. 249. Mitteilung [1]. Zur Umwandlung von Dehydroabietinsäure in 14α‐Methylsteroide I Die Partialsynthese von 5‐Methoxy‐17‐oxo‐14α‐methyl‐Δ^{5, 7, 9}‐des‐A‐östratrien

Wirthlin

Wehrli

Jeger

1974

Helvetica Chimica Acta

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“…Friedel-Crafts acylations have provided key units in the studies of the structural details of constituents of Calophyllum inophyllum nuts (59), Oxalis cernua flowers (S), neuroplegic compounds derived from phenothiazine (52,73) and related systems (34), podocarpic acid derivatives and analogs (12,32,81), khellin (28), diphenhydramine analogs (23), tetracycline analogs (55), Tabernanthe iboga alkaloids (49). dehydroabietane deriva lives (44), and new musk odorants (79).…”

Section: Applicationsmentioning

confidence: 99%

Friedel-Crafts Acylations.

Nelson¹

1959

Ind. Eng. Chem.

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Friedel-Crafts Acylations 1 he leveling off noted two years ago and the decline last year in the number and variety of Friedel-Crafts acylations seem to have stabilized. The fertile ingenuity of organic chemists continues to provide unique and interesting examples of this important reaction. This reaction class still continues to provide one or more key links in the successful synthesis of complex molecules in such diverse fields as dyes, perfumes, steroids, terpenes. alkaloids, and antibiotics as well as many more directly obvious applications.The tabulation form established in previous reviews is undergoing an experimental test of major importance. The tables with complete lists of references will be provided separately by the editor in photoprint form for those who need them. CatalystsThe importance of polyphosphoric acid as a mild reagent for effecting ringclosure acylations is a significant factor in the appearance of an extensive review of this reagent's utility (60).Zinc oxide is claimed to be a very effective nonhalogen catalyst for aryl acylations (61). Better yields with less undesirable by-products are obtained when nitromethane is included in the reaction medium for acylating phenols and phenol ethers. Tetrachloroethane seemed to be the most desirable solvent (64). Silicon tetraacetate gave only moderate or fair yields of 2-acetylthiophene with stannic chloride, zinc Cilio-. LeROI NELSON is associate professor of organic chemistry at Brigham Young University. He graduated from Utah State Agricultural College and obtained his Ph.D. from Purdue University in 1952. Previous experience includes postdoctoral research at UCLA and teaching at Purdue and Wayne Universities. Nelson is a member of the ACS,

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“…Completion of the sequence to methyl deoxypodocarpate (31) was achieved by hydrolysis of the dithiane (to 30)18 and decarbonylation utilizing Wilkinson's c a t a 1 y~t . I~ This approach constitutes the first efficient use of the Z,E mixture of isomers at the A/B ring juncture of tricyclic ketone 7 in resin acid synthesis [20][21][22]. …”

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confidence: 99%

“…The filtrate was evaporated in vacuo and the residue taken up in 10 ml of carbon tetrachloride. The undissolved solids (mainly additional rhodium salts) were removed by filtration, and the product was purified by TLC (10% ether in hexane) to give 58 mg (64%) of 31, mp 126.5-1 27.0°, identical by ir and NMR with an authentic sample of optically pure methyl deoxypodocarpate 21. Anal.…”

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confidence: 99%

New synthetic reactions. Geminal alkylation via .alpha.-trimethylenedithiocyclobutanones

Trost¹,

Preckel²,

Leichter³

1975

J. Am. Chem. Soc.

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A new geminal alkylation procedure based upon cyclobutanone spiroannelation with diphenylsulfonium cyclopropylide and I-lithiocyclopropyl phenyl sulfide followed by cyclobutane ring cleavage replaces the C-0 bonds of a carbonyl group by C-C bonds. Facilitation of ring cleavage by introduction of sulfur substituents CY to the carbonyl group of the cyclobutanone is required. The nucleophiles that initiated ring cleavage include hydroxide, methoxide, and methyllithium. In this way, a carboxylic acid or ester or ketone possessing the dithiane derivative of CHlCHO in the a position is created. While the versatility of this type of functionality is broad, it has been specifically demonstrated for the creation of a-methyl carboxylic esters and a novel cyclopentenone synthesis. Since the cyclobutanone spiroannelation is highly stereoselective, this geminal alkylation procedure is highly stereoselective. Thus, syntheses of .methyl deoxypodocarpate from 4ap-methyl-1,2,3,4,4a,9,10,1 Oa-octahydro-I-phenanthrene and of 3-carbomethoxy-6,10-dimethylspiro[4.5]dec-6-en-l -one, a potential precursor of hinesol, from 2,6-dimethylcyclohex-2-enone are described.The overall transformation represented by eq 1 involves the net replacement of the carbon-oxygen bonds of a carbonyl group with carbon-carbon bonds, a geminal alkylation. In the preceding paper, the cleavage is accomplished utilizing X = Br.3 Several limitations of the method are obvious. For example, the rigorousness required to achieve geminal bromination would eliminate the presence of isolated double bonds in the substrate. Cyclobutanones obtained by spiroannelation of aldehydes would brominate preferentially at the more substituted rather than less substituted side. A further complication involves the competition between ring cleavage and ring regression (semibenzylic acid rearrangement) with 1. Methods to overcome these prob-1 lems become even more important since cyclobutanones are also easily available from olefins as well as carbonyl partn e r~.~ These procedures can become stereospecific olefinic alkylations. In this paper, we wish to report in detail our results which attack this problem.Sulfur, like bromine, is an anion-stabilizing group but, unlike bromine, is a poor leaving group. Introduction of a geminal sulfur grouping should facilitate ring cleavage but preclude the reaction of ring regression. Equation 2 outlines the approach.The cyclobutanones employed in this study, 2-6, were prepared as previously reported utilizing diphenylsulfonium cycl~propylide~ or 1 -1ithiocyclopropyl phenyl sulfide6 followed by rearrangement of the initial adducts. We have recently discovered that lithium fluoroborate' is a superior acid catalyst for the rearrangement of oxaspiropentanes to cyclobutanones. Its advantages lie in its greater reproducibility, its faster rates, and its higher solubility in hydrocarbon solvents compared with lithium p e r~h l o r a t e .~.~ Although rearrangements were normally effected in refluxing benzene, room temperature also suffices with increased ...

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Rearrangements and Oxidations of Tricarbocyclic Diterpenes¹

Cited by 56 publications

References 4 publications

Steroide und Sexualhormone. 249. Mitteilung [1]. Zur Umwandlung von Dehydroabietinsäure in 14α‐Methylsteroide I Die Partialsynthese von 5‐Methoxy‐17‐oxo‐14α‐methyl‐Δ^{5, 7, 9}‐des‐A‐östratrien

Steroide und Sexualhormone. 249. Mitteilung [1]. Zur Umwandlung von Dehydroabietinsäure in 14α‐Methylsteroide I Die Partialsynthese von 5‐Methoxy‐17‐oxo‐14α‐methyl‐Δ^{5, 7, 9}‐des‐A‐östratrien

Friedel-Crafts Acylations.

New synthetic reactions. Geminal alkylation via .alpha.-trimethylenedithiocyclobutanones

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Rearrangements and Oxidations of Tricarbocyclic Diterpenes1

Cited by 56 publications

References 4 publications

Steroide und Sexualhormone. 249. Mitteilung [1]. Zur Umwandlung von Dehydroabietinsäure in 14α‐Methylsteroide I Die Partialsynthese von 5‐Methoxy‐17‐oxo‐14α‐methyl‐Δ5, 7, 9‐des‐A‐östratrien

Steroide und Sexualhormone. 249. Mitteilung [1]. Zur Umwandlung von Dehydroabietinsäure in 14α‐Methylsteroide I Die Partialsynthese von 5‐Methoxy‐17‐oxo‐14α‐methyl‐Δ5, 7, 9‐des‐A‐östratrien

Friedel-Crafts Acylations.

New synthetic reactions. Geminal alkylation via .alpha.-trimethylenedithiocyclobutanones

Contact Info

Product

Resources

About

Rearrangements and Oxidations of Tricarbocyclic Diterpenes¹

Steroide und Sexualhormone. 249. Mitteilung [1]. Zur Umwandlung von Dehydroabietinsäure in 14α‐Methylsteroide I Die Partialsynthese von 5‐Methoxy‐17‐oxo‐14α‐methyl‐Δ^{5, 7, 9}‐des‐A‐östratrien

Steroide und Sexualhormone. 249. Mitteilung [1]. Zur Umwandlung von Dehydroabietinsäure in 14α‐Methylsteroide I Die Partialsynthese von 5‐Methoxy‐17‐oxo‐14α‐methyl‐Δ^{5, 7, 9}‐des‐A‐östratrien