R. C. CAMBIE's research while affiliated with University of Auckland and other places
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Publications (490)
Iodine/potassium carbonate induced cyclization of hydroxyanthraquinones with ortho-allyl side chains gives iodomethyldihydrofuran anthraquinones which undergo a novel cyclopropanation reaction on treatment with methanolic potassium hydroxide, e.g. (9) gives (12) in 77% yield, and (10) gives (13) in 62% yield. The scope of the reaction is explored a...
Metal chloride cyclizations of the 4-demethoxy anthraquinonyl 1′,3'-dioxan (6) are highly diastereoselective , giving 9-chloro-9-methylanthracyclinones in high yield. The selectivity is inversely proportional to the strength of the Lewis acid, with the mild Lewis acid tin(IV) chloride/ dimethylformamide affording an 82% yield of the diastereomer (2...
6-(Decahydro-1,4,4-trimethyl-8-methylene-1-azulenyl)-7-hydroxy-2,8-dioxabicyclo[3.3.0]octan-3-one, C20H30O4, M(r) = 334.46, orthorhombic, P2(1)2(1)2(1), a = 8.614 (3), b = 13.441 (1), c = 15.948 (2) angstrom, V = 1846.5 (9) angstrom 3, Z = 4, D(m) = 1.17 (1), D(x) = 1.20 g cm-3, Mo K-alpha, lambda = 0.71069 angstrom, mu = 0.88 cm-1, F(000) = 712, T...
Two phthalide derivatives (7) and (8) have been prepared from podocarpic acid (1) via directed ortho metallation. The ring-c aromatic 16-oxa-17-oxo androstane analogue (8) was reacted with dimethyl acetylenedicarboxylate to give the 1,4-epoxy decahydrochrysene derivatives (9) and (10). The stereoisomer (10) was aromatized under acidic conditions to...
Complexation of the CpRu+ moiety to derivatives of three naturally occurring ring-C aromatic diterpenoids has been achieved in high yields under mild conditions. Assignment of stereochemistry in the resulting epimeric pairs of salts has been made by detailed analyses of their NMR spectra.
Methods for the preparation of methyl 3-formyl-1,4-dimethoxy-9,10-dioxo-9,10-dihydroanthracene-2-acetate (1) from quinizarin (8) have been investigated. Reaction of the ester (1) with either a titanium enolate of acetone or with acetone trimethylsilyl enol ether and titanium tetrachloride gave the aldol (29) which was then converted into the pentac...
Double nucleophilic aromatic substitution reactions between (cyclopentadienyl)(eta-6-1,2-dichlorobenzene)iron(1 +) salts and substituted 1,2-benzenediols have been carried out under mild conditions to prepare [eta-6-dibenzo[b,e][1,4]dioxin]iron(1 +) complexes functionalized in the 1- or 2-position with an alkyl, aldehyde, carboxylic acid, methoxyca...
Reaction of tetracarbonylmangenese(I) complexes derived from a diterpenoid aryl aldehyde or aryl methyl ketone with acetylene or ethylene leads to cyclopentaannulation to give 1H-inden-1-ols or 1H-indan-ols, respectively.
The cycloaddition of substituted furans to the diterpenoid aryne, generated by in situ diazotization of the anthranilic acid followed by cleavage of the annulated 1,4-epoxydecahydrochrysenes, provides a convenient method for the preparation in high yield of the previously unknown 1-substituted octahydrochrysen-4-ols. Use of 1,3-dipoles under the sa...
The reaction of some podocarpa-6,8,11,13-tetraenes with m-chloroperbenzoic acid in either a one-phase system or a two-phase system with an aqueous buffer leads to epoxide-opened products. Successful epoxidations have been achieved in high yield by using the neutral oxidant dimethyldioxiran. The hydroboration -oxidation of methyl 12-benzyloxypodocar...
Methyl 13-(N,N- diethylcarbamoyl )-12-methoxypodocarpa-8,11,13-trien-19-oate (2), 13-(N,N- diethylcarbamoyl )-12,19-dimethoxypodocarpa-8,11,13-triene (8) and N,N-diethyl-2-methoxy-4,5-dimethylbenzamide (15) were prepared for studies involving lithiation directed ortho to the tertiary amide group, in which the use of a LICKOR base was advantageous....
Anomoian A [1], a new bromotyrosine-derived metabolite, has been isolated from the Verongid sponge Anomoianthella popeae, belonging to a new genus of the family Ianthellidae.
In a continuation of a recent survey of the wood extractives of the Podocarpaceae (1,2), we report here those of Decussocarpus wallichianus (C. Presl) de Laub. (syn. Podocarpus wallichianus C. Presl), an important timber tree in the Southeast Asian region. The occurrence of totaryl derivatives in this and other species (1,2) suggests that they are...
In addition to known spongian diterpenes 1, 2, and 3, the new compounds 3β-acetoxy-19-hydroxyspongia-13(16), 14-dien-2-one [4], 19-hydroxyspongia-13(16), 14-dien-3-one [5], and 2α,19-dihydroxyspongia-13(16), 14-dien-3-one [10] have been isolated from the Dictyoceratid sponge Hyatella intestinalis.
In addition to the known linear sesterterpene furospinulosin 1 [6], the new compound 22-deoxyvariabilin [2] was isolated from the marine sponge Thorecta sp.
11, 19-Dideoxyfistularin 3 [3] and 11-hydroxyaerothionin [6], two new bromotyrosine-derived metabolites, have been isolated from the verongid sponge Pseudoceratina durissima, along with the known compounds aerothionin [1] and homoaerothionin [2].
Spongian-16-one [2] and spongia-15,16-dione [3], two new diterpenes with the spongiane skeleton, have been isolated from the dendroceratid sponge Dictyodendrilla cavernosa.
Stereoselective hydroxylation with thallium(I) acetate and iodine: trans- and cis-1,2-cyclohexanediols
The Maori people were early New Zealand settlers of Polynesian descent. The incidence of non-infectious diseases appears to have been low in these people, perhaps in part due to the presence of protective chemical constituents within their food plant supply. Three of the tropical crops they introduced are still eaten here today: the sweet potato or...
The sponge Hamigera tarangaensis has yielded eight new compounds and we report here the structure of one of these compounds, hamigeran A, C(20)H(25)BrO(5), or methyl 7-bromo-4beta,6-dihydroxy-1beta-isopropyl-3aalpha,8-dimethyl-5-oxo-1a,3a,4,5-tetrahydrocyclopenta[a]naphthalene-4-carboxylate, and the decomposition product of hamigeran D, C(21)H(28)B...
[563-68-8] C2H3O2Tl (MW 263.43) InChI = 1S/C2H4O2.Tl/c1-2(3)4;/h1H3,(H,3,4);/q;+1/p-1 InChIKey = HQOJMTATBXYHNR-UHFFFAOYSA-M [7553-56-2] I2 (MW 253.80) InChI = 1S/I2/c1-2 InChIKey = PNDPGZBMCMUPRI-UHFFFAOYSA-N (preparation of vic-iodoacetates for Prevost (dry) and Woodward–Prevost (wet) conversion of alkenes into trans- and cis-diols;1 for iodolact...
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and...
Seven-new compounds (1-6 and 10) with a unique carbon skeleton have been isolated from the sponge Hamigera tarangaensis, and the structure of a previously reported metabolite has been revised from 12 to 8. The structures have been assigned from extensive NMR examination. Compounds 3-6 showed moderate in-vitro cytotoxicity against P-388, while 3 sho...
Seventeen monoterpenoids, six sesquiterpenoids, and nine diterpenoids have been identified by GC/MS in the essential oil of the mature foliage of Podocarpus totara G. Benn ex D. Don. The major monoterpenoids were α-pinene, sabinene, limonene, α-terpinene and α-terpineol. The major sesquiterpenes were β-elemene, α-humulene, β-caryophyllene, and β-se...
The structures of 1-methoxy-4-(2-methylprop-2-enyloxy)-2-[(2R,6R)-4,4,6-trimethyl- 1,3-dioxan-2-yl]anthraquinone, C26H28O6, and 4-hydroxy-3-(2-methylprop-2-enyl)-2-[(2R,6R)-4,4,6-trimethyl-1,3-dioxan-2-yl]anthraquinone, C25H26O5, have been determined to compare their conformations with those determined for solutions by H-1 NOESY (nuclear Overhauser...
The structures of scalarolide (12 beta-hydroxyscalar-17-en-24,25-olide) [alternative name (5 alpha,12 beta)-17a,17-lactone-12-hydroxy-17-(hydroxymethyl) -4,4,8 -trimethyl-D-homoandrost-17-ene-17a-carboxylic acid], C25H38O3, from a Cacospongia sponge and scalarin (12 alpha-acetoxy-25 alpha-hydroxyscalar-16-en-25, 24-olide) methanol solvate {alternat...
Attempts to alkylate products from Birch reductions of derivatives of podocarpic acid are reported. Attempted reductive silylation of ring c of methyl 12-methoxypodocarpa-8,11,13-trien-19-oate (5) gives products of C4 ester reduction only. The enantiopure form of the bis(ethylene acetal) (15) of 19-norpodocarp-8-ene-3,12-dione, a potentially useful...
(+)-Bis[3-(heptafluorobutyryl)camphorato]oxovanadium(IV) [(+)-VO(hfc)2] (2) is an effective catalyst for the hetero-Diels-Alder reaction of a variety of anthraquinone aldehydes and silyloxy dienes giving high yields of cycloadducts. The reactions all proceed with strict endo topology giving rise to cis products; this indicates that they follow a si...
Reactions between benzaldehyde or o-anisaldehyde and a
series of silyloxy dienes catalysed by the chiral acyl- oxyborane (CAB)
complex (4) give high yields of enantioselective products from a Mukaiyama
aldol rather than a hetero-Diels–Alder reaction. Attempts to effect a
similar catalytic reaction with anthraquinone aldehydes were unsuccessful but...
The methylidene tetracycle (2) has been synthesized in 11 steps from
quinizarin (5) in an overall yield of 38% by using a highly ecient
selective dihydroxylation step and an intramolecular ene cyclization. Also
prepared with the selective dihydroxylation methodology were the silyloxy
alkene (3) and the 6-demethoxy alkene (4). A mixture (1 : 2) of t...
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and...
Syntheses of C2 anthraquinone aldehydes from the commercially available anthrarufin (1) have been investigated. A synthesis of the keto aldehyde (2) in nine steps and 73% overall yield was achieved. Syntheses of (2) exploiting selective oxidations of either a C-bound allyl group by Wacker oxidation to introduce the methyl keto functionality or of a...
A new sesterterpene 12-O-desacetylfuroscalar-16-one (1) has been isolated from the sponge Cacospongia sp., and its structure was determined by spectroscopic examination.
The stereochemistry of the epoxide ring of the title compound, 12,12-ethylenedioxy-8 alpha,9 alpha-epoxypodocarpan-19-oic acid, C19H28O5, prepared during studies aimed at converting podocarpic acid into precursors for the synthesis of biologically active quassinoids, has been confirmed by X-ray structure determination.
The stereochemistry of the epoxide ring of the title compound, 12,12-ethylenedioxy-8α, 9α-epoxypodocarpan-19-oic acid, C19H28O5, prepared during studies aimed at converting podocarpic acid into precursors for the synthesis of biologically active quassinoids, has been confirmed by X-ray structure determination.
8,13–Epoxy–3β–hydroxylabd–14–en–2–one (1) from the wood of Lagarostrobos colensoi has been converted in 25% overall yield into 8α–acetoxy–2β,3β–dihydroxy–13,14,15,16–tetranorlabdan–12–oic acid (2), a useful intermediate for synthesis.
The structure of a naphthalene derivative obtained by rearrangement of 13-methoxytotara-5,8,11,13-tetraen-7 alpha-ol (2) has been revised to 5-(5'-isopropyl-6'-methoxy-2'-methyl-1'-naphthyl)-2-methylpent-2-ene (7). A minor oxidation product of 13-methoxytotara-8,11,13-triene (4) has been identified as 4-methoxy-3,3-dimethyl-7-(1',3',3'-trimethyl-2'...
The radical decarboxylation-sulfoxide cycloelimination of 2′-pyridylthio esters formed from a series of podocarpic acid derivatives gives Δ4(18)-alkenes in high yield. An exception is the 13-nitro acid (2) which affords a thiohydroxamic ester (28), the relative stability of which is attributed to inhibition of the radical chain reaction by the nitr...
Methods for the oxidation of the aryl ring of derivatives of podocarpic acid have been examined. Oxidation of methyl 12-hydroxypodocarpa-8,11,13-trien-19-oate (2) with phenyliodonium diacetate in various solvents gives 8β-substituted dienones. An 8β-chloro dienone is formed during oxidation of the phenol (2) with τ-butyl hypochlorite. Oxidation of...
Two new abietanes, 6,11,14-trihydroxy-12-methoxyabieta-5,8,11,13-tetraene-3,7-dione (lycopod-abietane A) and 6,11,14-trihydroxy-12-methoxy-3 alpha,18-cycloabieta-5,8,11,13-tetraen-7-one (lycopod-abietane B), were isolated from Lycopodium deuterodensum together with lycopodine, alpha-onocerin, 21-episerratenediol, 21-episerratriol and 16-oxoserraten...
From the fronds of Gleichenia microphylla, two new clerodane glycosides were isolated. Their structures were determined to be (6S,13S)-6-[O-alpha-L-rhamnopyranosyl-(1-->6)-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-rhamnopyranosyloxy]-13-[O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-fucopyranosyloxy]cleroda-3,14-diene and (6S, 13S)-6-[O-alpha-L-rhamnopyra...
The first total synthesis of enantiopure triptoquinone F (6) starting from podocarpic acid (10) is reported, as well as formal syntheses of enantiopure triptoquinones D (4) and E (5). An acid-promoted Fries rearrangement of a benzannulated lactone (14) has been used as a direct, moderately high yielding route for introduction of C11 functionality....
The scope of acid-promoted Fries rearrangements of benzannulated lactones has been examined. The reaction is applicable to seven-membered lactones possessing a sufficiently activated aromatic ring but not to six-membered lactones, and it proceeds in higher yield for diterpenoid lactones than for lower molecular weight lactones. The structures of th...
A new unsaturated aryl keto acid (1) and its methyl ester (2) have been isolated from the wood of Fijian Xylocarpus moluccensis and their structures determined by spectroscopic examination.
Floribundal (1), the first example of a nonglycosidic bisiridoid has been isolated from the heartwood of Scaevola floribunda and its structure and relative stereochemistry determined by NMR spectroscopy and molecular modelling. The aglycon 2 of loganin was also isolated. A mixture of six novel delta-amyrin fatty esters with C-20-C-30 acid moieties...
Reinvestigation of the reductive rearrangement of 1,4-bis(2-chloro-2-propenyl)-9,10-anthraquinone with high quality sodium dithionite has given new products. We report here the structure of one of these compounds, 11-(2-chloro-2-propenyl)-5,11-dihydroxy-2-methylanthra[1,2-b]furan-6(11H)-one, C20H15ClO4.
Reaction of 7-oxototara-8,11,13-trien-13-yl acetate (3) with acetic anhydride-perchloric acid affords the γ-pyrone (8) in addition to the previously reported acetyl derivative (4). Baeyer-Villiger oxidations of the ketones (3) or (5) have given starting material or complex mixtures, but the ε-lactone (9) and the rearranged product (11) were isolate...
The iodination of thallium(I) salts of phenols is examined and the results are compared with those of the selective ortho-iodinating reagent thallium(I) acetate-iodine.
Methods for constructing the c-ring of nagilactones from the ring c ozonolysis products of methyl podocarpate have been investigated. The stereochemistry of an aldol adduct (15) and the structure of a dihydropyridazinone derivative (17) have been confirmed by X-ray crystallography.
Two new phytoecdysteroids, named schizaeasterones A and B, were isolated from the fronds of Schizaea dichotoma. Their structures were determined to be (20R,22R,24R)-3β,11α,14α,20,22-pentahydroxy-24-methyl-5β-cholest-7-en-6- one and (20R,22R,24ξ,25ξ)-3β,11α 14α,20,22,26-hexahydroxy-24-ethyl-5β- cholest-7-en-6-one, respectively, from spectral data.
Conformational changes in N,N-diethyl-14-hydroxy-12,19-dimethoxypodocarpa-8,11,13-triene-13-carboxamide were studied by variable-temperature 1H and 13C NMR over the range 228–328 K using three hydrogen and six carbon indicator sites. The parameters ΔH≠ = 48.7±2.0 kJ mol−1, ΔS≠ = −23±7 J K mol−1 and ΔG298≠ = 55.6±4.3 kJ mol−1 were obtained, which we...
A sponge from the new genus Petrosaspongia has yielded two new isomeric sesterterpene lactones. We report here the structure of one of these lactones, [4aS-(4aα,4bβ,6aα,7β,8aα,11aβ,12β, 13aβ,13bα,15aβ)]-12-acetoxyoctadecahydro-1,1,4a,13b-tetramethyl- 7,11a-epoxy-2H-furo[2,3-b]phenanthro[1,2-f]oxocin-10(11 H)-one, C27H40O6.
Reductive Claisen rearrangement of allyloxyanthraquinones can be carried out effectively with sodium metabisulfite. Unlike sodium dithionite, the reagent does not effect loss of methoxy groups para to the rearranging allyl group.
Double nucleophilic aromatic substitution reactions between N-substituted (ν6-1,2-dichlorobenzene)RuCp+ salts and substituted 1,2-benzenediols have been carried out under mild conditions to prepare N-substituted (ν6-dibenzo[b,e][1,4]dioxin)ruthenium(II)) complexes. The dibenzodioxin ligands were subsequently liberated to photolysis, with radiation...
Diastereoselective formation of 9-fluoro-9-methylanthracyclinones has been achieved by treating ortho-methallyl-substituted anthraquinonyl homochiral dioxans with boron trifluoride etherate . The demethoxy anthraquinonyl dioxan (16) underwent slow reaction to give exclusively the (7S,9R) fluoro tetracycle (21) in 58% yield. The dimethoxy anthraquin...
Treatment of methyl 12-hydroxypodocarpa-8,11,13-trien-19-oate (5) with a commercial sample of thallium(III) trifluoroacetate gave a low yield (5%) of a non-symmetric ether-linked dimer (15). Use of freshly prepared thallium(III) trifluoroacetate gave a 28% yield of the symmetrical biaryl dimer (16). The dimethyl ether (17) was prepared in low yield...
Metal chloride cyclizations of the 4-demethoxy anthraquinonyl 1′,3'-dioxan (6) are highly diastereoselective , giving 9-chloro-9-methylanthracyclinones in high yield. The selectivity is inversely proportional to the strength of the Lewis acid, with the mild Lewis acid tin(IV) chloride/ dimethylformamide affording an 82% yield of the diastereomer (2...
Methods for the preparation of methyl 3-formyl-1,4-dimethoxy-9,10-dioxo-9,10-dihydroanthracene-2-acetate (1) from quinizarin (8) have been investigated. Reaction of the ester (1) with either a titanium enolate of acetone or with acetone trimethylsilyl enol ether and titanium tetrachloride gave the aldol (29) which was then converted into the pentac...
A novel bromo benzocyclooctane [1] has been isolated from the sponge Hamigera taragensis and its structure determined by spectroscopic examination of its triethyl ether [3].
Five new glycosides, 3,4-dihydroxyphenethyl alcohol 4-O-caffeoyl-beta-D-allopyranoside, (6S,13S)-13-beta-D-fucopyranosyloxy-6-(beta-D-fucopyranosyl -(1-->2)-[beta-D-fucopyranosyl-(1-->4)-alpha-L-rhamnopyranosyloxy]) -cleroda-3,14-diene, (6S,13S)-13-beta-D-fucopyranosyloxy-6-(beta-D-quinovopyranosyl -(1-->2)-[beta-D-fucopyranosyl-(1-->4)-alpha-L-rha...
Functionalization of the (η6-arene)tricarbonylchromium(O) complexes of some podocarpic acid (1) derivatives has been achieved through the addition-protonation route. The resulting dienol ethers underwent acid-promoted hydrolysis giving enones which were subsequently reduced to saturated ketones. Acid-promoted cyclopentaannulation of these ketones p...
Citations
... Consequently, the absolute configuration of 3 could be deduced to be 1R,2S,6S,10R,13S. In addition to the isolation of the above new compounds 1-3, 10 known compounds, including schizaeasterone A (4) [12], terretonin (5) [13], demethylincisterol A 2 (6) [14], asperophiobolin E (7) [15], butyrolactone I (8) [16], butyrolactones VI (9) [17], epi-aszonalenins B (10) [18], flavoglaucin (11) [19], 6,8-dimethoxy-3-methylisocoumar (12) [20], and methyl shikimate (13) [21] were also isolated and identified from this fungus. Their structures ( Figure 1) were elucidated through a comparison of their NMR and MS data with reported literature. ...
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... However, M. barbigera belongs to section Pelea and no other species of that section so far has been tested for the presence of acetophenones. The occurrence of alloevodionol and its derivatives in at least five Melicope species belonging to three different sections as well as Medicosma [64,71,72], shows that some acetophenones and chromenes seem to be more ubiquitous in Melicope and related genera and are thus not chemotaxonomically informative. Chromenes and acetophenones found in Melicope generally are prenylated phloroglucin derivatives containing terpenoid side chains, e.g., isopentenyl-or geranylmoieties. ...
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... In the 1993 Cambie et al. showed the synthesis of the 9chloro-9-fluoro derivative [54], then they continued the study for the introduction of fluorine at C9 in an anthracyclinone, so in the 1996 showed the synthesis of 9fluoro-9-methylanthracyclinones (30 trifluoride etherate. In this case the yields of the fluoroderivatives were better that in earlier work [57]. Although all these studies, the first synthesis of a natural anthracycline modified in position 9 with the introduction of a fluoro has been showed in 1997 [58]. ...
... 201 During further investigations by the Rutledge group, it was found that treatment of iodide 86 with ethanolic potassium hydroxide under reflux gave the pentacyclic product 87 in which the allyl group had isomerized (Scheme 16). 202 Under these reaction conditions, a serendipitous cyclopropanation also occurred, resulting in the interesting fused pentacyclic structure of 87. In the same paper, the authors also described how they synthesized compound 89 (as a mixture of the methyl and ethyl phenyl ethers) from 88 under similar conditions (Scheme 16). ...
Reference: Isomerization of Allylbenzenes