<b>The Reaction of 7-Norbornadienyl and 7-Dehydronorbornyl Derivatives with Borohydride under Solvolytic Conditions--Evidence for the Tricyclic Nature of the Corresponding Cations</b>

Brown, Herbert C.; Bell, Harold M.

doi:10.1021/ja00898a030

Cited by 51 publications

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Compound 9c was obtained as an oil, v,,,(NaCl)/cm-' 3550, 3050, 1610, 1175, 860 and 740; 6,(400 MHz) 7.83 (2 H, d, J 8.3, ArH),7.36(2H,d, J8.3,ArH),5.70(1 H,d, J6.6, 15-H), 5.63(1 H, d, J6.6, 16-H), 4.87 (1 H, s, 14-H), 3.88 (1 H, dd, J 3 . 2 and 2.45 (3 H, s, ArMe) and 0.87, 0.80 and 0.76 (3 H each, each s, 4-Me2 and 10-Mee); m/z 474 (M', 0.4%), 317 (3), 304 (8), 303 (34), 301 (8), 285 (34) and 173 (100);6, see Table 1. 2.5,7-H),3.50(1 H,d, J11.7, 17-H),3.46(1 H,d, J11.7, 17-H'), Beyer-l5-ene-7a, 17-diol[( -)-Benuol] 3.-A solution of tosyl ester 9c (20.7 mg, 0.04 mmol) in HMPA (0.5 cm3) was treated with sodium iodide (78.5 mg, 0.52 mmol) and zinc powder (68.5 mg, 1.05 mmol) as for compound 1, to give a crude reaction mixture, which was subjected to column chromatography, using hexane-ethyl acetate (9: 1) as eluent, to afford the beyerene benuol 3 (10.7 mg, 81%) as a solid, m.p. 116-117 "C (from hexane-CH,Cl,) (lit.,2d 114-1 16 "C);…”

Section: Preparation Of Cyclobutenesmentioning

confidence: 99%

Synthesis of C-17-functionalized beyerane diterpenes. Synthesis of (–)-erythroxylol B, (–)-erythroxydiol A and (–)-benuol

Abad¹,

Agulló²,

Arnó³

et al. 1994

J. Chem. Soc., Perkin Trans. 1

View full text Add to dashboard Cite

The title compounds 1, 2 and 3 became accessible from an appropriately functionalized podocarpenone 4 in short sequences of operations, in which the key step involves the toluene-psulfonic acid-induced rearrangement of 1 3-epimeric epoxides 6 and 7.The presence of a bridgehead hydroxymethyl group at C-13 is unique to some tetracyclic diterpenes of the beyerane group.' Erythroxylol B 1, isolated from Erythroxylon rnonogynurn, 2a erythroxydiol A 2, isolated from Erythroxylon monogynum,2a Helichrysum dendroideum,2b and Baccharis tola,2c and benuol3, isolated from Sideritis serrata,2d are some representative examples of beyeranes containing this characteristic moiety.? beyerane skeleton 1 R'=Me,R2=H 3 R' = Me, R2 = OH 2 R' = CHZOH, R2 = H 10 11 Qa X=OTs ii Scheme 2 12 13Puper 4/02765E

show abstract

Section: Preparation Of Cyclobutenesmentioning

confidence: 99%

Synthesis of C-17-functionalized beyerane diterpenes. Synthesis of (–)-erythroxylol B, (–)-erythroxydiol A and (–)-benuol

Abad¹,

Agulló²,

Arnó³

et al. 1994

J. Chem. Soc., Perkin Trans. 1

View full text Add to dashboard Cite

show abstract

“…Hydride attack on 32 could then occur at C-17 to afford the cyclopropyl derivative 30 (Scheme 15). This reaction represents the first reported example of this type of skeletal rearrangement among the diterpene alkaloids, though homoallylic carbocation rearrangements have ample precedents in other systems (14)(15)(16).…”

mentioning

confidence: 88%

“…They may have been eliminated as minor products during the repeated crystallization of the perchlorate salt. 11-Dehydrohetisine[15] and 2,11 -didehydrohetisine[16] undergo an interesting rearrangement in strong acid solution. These compounds were prepared by oxidation of 3 mp 278.0-279.5°R atio 3:4 =1:3 8 1 l-e/J/'-hetisine mp 268-271°S cheme 4 4 mp 288-290"…”

mentioning

confidence: 99%

Studies in the Chemistry of Natural Products: Rearrangement Reactions of Diterpenoid and Norditerpenoid Alkaloids

Pelletier¹

1992

J. Nat. Prod.

View full text Add to dashboard Cite

The diterpenoid nitrogenous bases from the plant families Compositae, Escalloniaceae, Garry aceae, Ranunculaceae, and Rosaceae have long been of interest because of their pharmacological properties, complex molecular structures, and interesting chemistry. Most of these alkaloids have been isolated from species of Aconitum and Delphinium (Ranunculaceae) and Garrya (Garryaceae). With respect to the chemistry, several unusual acidcatalyzed and base-catalyzed rearrangements of diterpenoid and norditerpenoid alkaloids are discussed. Certain rearrangement products produced under solvolytic conditions are considered.Diterpenoid nitrogenous bases occur in the plant families Compositae, Escalloniaceae, Garry aceae, Ranunculaceae, and Rosaceae and have long been of interest because of their pharmacological properties, complex molecular architecture, and interesting chemistry. Most of the alkaloids have been isolated from species of Aconitum and Delphinium (Ranunculaceae) and Garrya (Garryaceae). A few diterpenoid alkaloids have been also isolated from Spiraea (Rosaceae) species and from two Anopterus (Escalloniaceae) species (Table 1). Table 1. Plant Genera Containing Diterpenoid Alkaloids. COMPOSITAE Inula royleana ESC ALTON I ACE AE Anopterus gladulosus Anopterus macleayanus GARRYACEAE Garrya laurifolia Garrya ovata var. lindheimeri Garrya veatchii RANUNCULACEAE Aconitum sp. Consolida ambigua Delphinium sp. ROSACEAE Spiraea sp.

show abstract

“…reveal this molecule to possess at a minimum some degree of homoaromatic character in the bridged cycloheptatriene portion of the structure. A more definite assessment of rr-electron distribution and structural dimension in this ring system has been realized by synthesis of the 6,7-benzo derivative (76) and X-ray structure analysis of this crystalline substance[39! With precise knowledge of key distances C -4 a x -8a = 2.44 and C-2-C-3 = 2.54 A and the relative orientations of the p orbitals at these four sites, the respective overlap integrals were determined to be 0.061 and 0.050, respectively.…”

Section: Neutral Systemsmentioning

confidence: 99%

The Realities of Extended Homoaromaticity

Paquette

1978

Angew. Chem. Int. Ed. Engl.

View full text Add to dashboard Cite

Homoaromaticity has been the subject of many investigations and continues to remain an extraordinarily rich area of chemistry. Quantitative experimental evaluation of the level of long range delocalization and assessment of interactions in molecules having two or more insulating atoms, together with various theoretical estimates of energies and geometries, are areas currently being examined. The primary intention of this review is to provide a critical up-to-date survey of relevant spectral and structural data, as well as an analysis of the many reactions believed to involve generation of homoaromatic ions. Extensively discussed are mono-, bis-, and trishomoaromatic systems arranged on the basis of their cationic, anionic, or uncharged nature. Presentation of these individualized segments is preceded by a brief analysis of homoaromatic overlap.

show abstract

The Reaction of 7-Norbornadienyl and 7-Dehydronorbornyl Derivatives with Borohydride under Solvolytic Conditions--Evidence for the Tricyclic Nature of the Corresponding Cations

Cited by 51 publications

References 0 publications

Synthesis of C-17-functionalized beyerane diterpenes. Synthesis of (–)-erythroxylol B, (–)-erythroxydiol A and (–)-benuol

Synthesis of C-17-functionalized beyerane diterpenes. Synthesis of (–)-erythroxylol B, (–)-erythroxydiol A and (–)-benuol

Studies in the Chemistry of Natural Products: Rearrangement Reactions of Diterpenoid and Norditerpenoid Alkaloids

The Realities of Extended Homoaromaticity

Contact Info

Product

Resources

About