Aromatic Annulation Strategy for the Synthesis of Angularly-Fused Diterpenoid Quinones. Total Synthesis of (+)-Neocryptotanshinone, (-)-Cryptotanshinone, Tanshinone IIA, and (.+-.)-Royleanone

Danheiser, Rick; Casebier, David S.; Firooznia, Fariborz

doi:10.1021/jo00131a006

Cited by 73 publications

(37 citation statements)

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“…More recently, a photochemical aromatic annulation has been applied to the synthesis of several diterpenoid quinones. [10] One of the more convergent approaches reported up to date relies on a Diels ± Alder reaction between an adequately substituted benzoquinone and 1,3,3-trimethyl-2-vinylcyclohexene as a key step. [11] In connection with our research devoted to asymmetric Diels ± Alder reactions with enantiomerically pure sulfinyl quinones, [12] we focused on these diterpenoid quinones bearing the angularly fused tricyclic skeleton with the aim of finding a general approach to efficiently create the C-10 asymmetric center.…”

Section: Introductionmentioning

confidence: 99%

Enantioselective Synthesis of (+)-Royleanone from Sulfinyl Quinones

Carreño¹,

Ruano²,

Toledo³

2000

Chem. Eur. J.

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Section: Introductionmentioning

confidence: 99%

Enantioselective Synthesis of (+)-Royleanone from Sulfinyl Quinones

Carreño¹,

Ruano²,

Toledo³

2000

Chem. Eur. J.

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“…When we treated 9 under the same conditions as used by Danheiser et al 46) no cyclization reaction product was detected.…”

Section: Resultsmentioning

confidence: 90%

“…Danheiser et al 46) described a cyclization reaction of 8 with H 2 SO 4 in ethanol to obtain cryptotanshinone, which had the D-ring on C-14. On the same lines, we treated 3 with aqueous potassium hydroxide in THF (Chart 1), obtaining a compound that was identified from its spectroscopic data as 16-hydroxycolumbaridione (9) as follows.…”

Section: Resultsmentioning

confidence: 99%

Quinone Derivatives by Chemical Transformations of 16-Hydroxycarnosol from Salvia Species

Marrero

Andrés

Luis

2005

CHEMICAL & PHARMACEUTICAL BULLETIN

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The known diterpenes 12,16-epoxycarnosol (2), isotanshinone II (6), and (؉)-neocryptotanshinone (8) were obtained by partial synthesis from 16-hydroxycarnosol (1), a C-16 hydroxylated abietatriene diterpene isolated in relative abundance from the aerial part of Salvia mellifera GREENE. The physical and spectroscopic data of these semisynthetic diterpenes were identical to those given for the natural ones in the literature. These abietane diterpenes have very interesting biological activities and the semisynthetic approach described here represents an alternative to obtain them from other major diterpenes isolated from Salvia species. Additionally, seven new semisynthetic diterpene analogues, 11,14-dioxo-12,16-epoxy-8,12-abietadien-20,7b b-olide (3), 11,14-dioxo-12,16-epoxy-8,12,15(16)-abietatrien-20,7b b-olide (4), 15,16-didehydro-12,16-epoxycarnosol (5), 1-oxoisotanshinone II (7), 16-hydroxycolumbaridione (9), 12,16-diacetoxycolumbaridione (10), and 14-methoxy-12,16-epoxycarnosol (13), were obtained from 1. The structures of the new compounds were established based on their spectroscopic data.

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“…198 This process is judged to be somewhat shorter and higher-yielding than the vinylketene route shown in Scheme 174. 194 The Fischer carbene method does however lack the flexibility of routes utilizing free vinylketenes, which may be derived from diverse precursors and offer a wider variety of reaction pathways. …”

Section: Scheme 177 Comparison With Other Methodsmentioning

confidence: 99%

“…The vinylketene required for the synthesis of (±)-royleanone is generated by a Wolff rearrangement and undergoes intermolecular [2+2] cycloaddition to a silyloxyalkyne (Scheme 174). 194 Adduct 167 is then formed by ring opening of the cycloadduct to form a new vinylketene that undergoes final electrocyclization. Adduct 167 is readily elaborated to the natural product.…”

Section: Scheme 173mentioning

confidence: 99%

Cycloaddition and Electrocyclic Reactions of Vinylketenes, Allenylketenes, and Alkynylketenes

Tidwell

2015

Organic Reactions

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Vinylketenes may be prepared by the typical procedures used for other ketenes, and are usually highly reactive, except when bulky groups and silyl substituents are present. They are extensively utilized in cycloaddition reactions and electrocyclizations, including dimerizations, inter‐ and intramolecular reactions with alkenes, alkynes, imines, and carbonyl groups, and intramolecular reactions with aryl and heteroaryl groups. These pericyclic reactions are widely used in syntheses of carbocyclic and heterocyclic products, and are particularly useful for the preparation of β‐lactams and β‐lactones. Allenylketenes and alkynylketenes also undergo cycloaddition and electrocyclic reactions.

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Aromatic Annulation Strategy for the Synthesis of Angularly-Fused Diterpenoid Quinones. Total Synthesis of (+)-Neocryptotanshinone, (-)-Cryptotanshinone, Tanshinone IIA, and (.+-.)-Royleanone

Cited by 73 publications

References 0 publications

Enantioselective Synthesis of (+)-Royleanone from Sulfinyl Quinones

Enantioselective Synthesis of (+)-Royleanone from Sulfinyl Quinones

Quinone Derivatives by Chemical Transformations of 16-Hydroxycarnosol from Salvia Species

Cycloaddition and Electrocyclic Reactions of Vinylketenes, Allenylketenes, and Alkynylketenes

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