Studies for a Diastereoselective Synthesis of the Tetracyclic Diterpenic Diol Stemarin: A Model Study for a New Preparation of the Key Intermediate and the Synthesis of (+)‐18‐Deoxystemarin

Berettoni, Marco; Bettolo, Rinaldo Marini; Montanari, Vittorio; Prencipe, Teresa; Romeo, Sergio

doi:10.1002/hlca.19910740807

Cited by 18 publications

(34 citation statements)

References 24 publications

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“…(+)-Podocarpic acid (4) was then used for obtaining (+)-stemod-12-ene (31) and (+)-2-deoxystemodinone (2d), thus confirming the absolute configuration attributed to the stemodane diterpenoids on the basis of ORD and CD studies [50]. (+)-Podocarpic acid (4) was also converted into (+)-aphidicol-15-ene (36) [51] and into the Stemodia chilensis tetracyclic diterpenoid (+)-19-acetoxystemodan-12-ol (2f) allowing confirmation of the structure attributed to the latter only on the basis of NMR experiments [54]. (+)-Podocarpic acid (4) was then extensively used in the work which led to the synthesis of (+)-stemar-13-ene (57) and (+)-18-deoxystemarin (3b) [55,56,59,60,62].…”

Section: Discussionmentioning

confidence: 58%

“…The starting material was known 33a (vide supra) which was converted [54] into the corresponding tosylate 55 (Scheme 10). The latter was then treated with Et 4 N(PhCOO) in acetone at reflux affording the exo-benzoate 56.…”

Section: Methodsmentioning

confidence: 99%

“…Thus refluxing the latter in benzene in the presence of TsOH gave (+)-stemar-13-ene (57) (see Section 8.5). Finally, epoxidation of the latter followed by LiAlH4 epoxide ring opening gave (+)-3b [54]. This synthesis was accomplished in 1991.…”

Section: Diastereoselective Synthesis Of (+)-Stemar-13-ene and (+)-18mentioning

confidence: 99%

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(+)-Podocarpic Acid as Chiral Template in the Synthesis of Aphidicolane, Stemodane and Stemarane Diterpenoids †

et al. 2016

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Abstract:In this review the synthetic work in the field of aphidicolane, stemodane and stemarane diterpenoids, in which readily available (+)-podocarpic acid (4) was used as chiral template for the construction of their polycyclic structures, is described as it developed along the years. In the frame of this work (+)-podocarpic acid (4) was a very useful tool in a model study leading to the syntheses of tetracyclic ketones 7 and 8, models of key intermediates 5a and 6 in the syntheses of (+)-aphidicolin (1) and (+)-stemodin (2a), respectively. (+)-Podocarpic acid (4) was also converted into (+)-2-deoxystemodinone (2d), allowing confirmation of the stemodane diterpenoids absolute configuration, into (+)-aphidicol-15-ene (36) and into Stemodia chilensis tetracyclic diterpenoid (+)-19-acetoxystemodan-12-ol (2f), allowing confirmation of its structure. (+)-Podocarpic acid (4) was then extensively used in the work which led to the synthesis of (+)-stemar-13-ene (57) and (+)-18-deoxystemarin (3b). Finally, (+)-4 was converted into (+)-2-deoxyoryzalexin S (66), which made it possible to demonstrate that the structure of (+)-66 could not be attributed to a Chilean Calceolaria isolated diterpenoid to which this structure had been assigned.

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Section: Discussionmentioning

confidence: 58%

Section: Methodsmentioning

confidence: 99%

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(+)-Podocarpic Acid as Chiral Template in the Synthesis of Aphidicolane, Stemodane and Stemarane Diterpenoids †

et al. 2016

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“…By Raney-Ni desulfurization, hydroxydithioacetals 1 and 2b were in fact transformed into bicyclo[2.2.2]octan-2-ols 6 and 7, and the latter rearranged 3 ) to the stemarane system (Scheme 1).…”

mentioning

confidence: 98%

“…-The 6-exo-hydroxybicyclo[2.2.2]octan-2-one ethylene dithioacetals 1 and 2b are key intermediates in the synthesis of the stemarane diterpenoids (AE)-stemarin (3) [1] [2], (þ)-13-stemarene (4) [3] [4] and (þ)-18-deoxystemarin (5) [3] [5], respectively.…”

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confidence: 99%

Synthesis of (+)‐13‐Stemarene and (+)‐18‐Deoxystemarin: Expeditious Preparation of the Key 6‐exo‐Hydroxybicyclo[2.2.2]octan‐2‐one Ethylene Dithioacetal

Leonelli

Caschera

Silvestri

et al. 2008

Helvetica Chimica Acta

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An expeditious preparation of the 6-exo-hydroxybicyclo[2.2.2]octan-2-one ethylene dithioacetal 2b, a key intermediate in the synthesis of (þ)-13-stemarene (4) and (þ)-18-deoxystemarin (5) is described. Compound 2b was obtained as the major product by equilibrating the endo rich mixture of 6-hydroxybicyclo[2.2.2]octan-2-one ethylene dithioacetals 2 with TsOH in benzene at reflux, easily available from the corresponding hydroxy ketones 9. The model experiments which preceeded the above transformation, not previously described in the literature, are also presented.Introduction. By Raney-Ni desulfurization, hydroxydithioacetals 1 and 2b were in fact transformed into bicyclo[2.2.2]octan-2-ols 6 and 7, and the latter rearranged 3 ) to the stemarane system (Scheme 1).Compounds 1 and 2b were efficiently prepared from the corresponding 6-exohydroxybicyclo[2.2.2]octan-2-ones 8 and 9b by thioacetalization with 1,2-ethanedithiol in the presence of BF 3 · Et 2 O [2] [6]. Given that 6-exo-hydroxybicyclo[2.2.2]octan-2-ones of the type of 8 and 9b are the minor products (endo/exo 85 : 15) of the intramolecular aldol condensation of a 3-oxocyclohexaneacetaldehyde [7] [8] (Scheme 2), the efficiency of the synthesis of stemarane diterpenoids, by this approach,

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ChemInform Abstract: Studies for a Diastereoselective Synthesis of the Tetracyclic Diterpenic Diol Stemarin: A Model Study for a New Preparation of the Key Intermediate and the Synthesis of (+)‐18‐Deoxystemarin.

et al. 1992

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Studies for a Diastereoselective Synthesis of the Tetracyclic Diterpenic Diol Stemarin: A Model Study for a New Preparation of the Key Intermediate and the Synthesis of (+)‐18‐Deoxystemarin

Cited by 18 publications

References 24 publications

(+)-Podocarpic Acid as Chiral Template in the Synthesis of Aphidicolane, Stemodane and Stemarane Diterpenoids †

(+)-Podocarpic Acid as Chiral Template in the Synthesis of Aphidicolane, Stemodane and Stemarane Diterpenoids †

Synthesis of (+)‐13‐Stemarene and (+)‐18‐Deoxystemarin: Expeditious Preparation of the Key 6‐exo‐Hydroxybicyclo[2.2.2]octan‐2‐one Ethylene Dithioacetal

ChemInform Abstract: Studies for a Diastereoselective Synthesis of the Tetracyclic Diterpenic Diol Stemarin: A Model Study for a New Preparation of the Key Intermediate and the Synthesis of (+)‐18‐Deoxystemarin.

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