Wagner-Meerwein rearrangements of longipinane derivatives

Román, Luisa U.; Hernández, José Falcón; Río, Rosa E. del; Bucio, María A.; Cerda-Garcı́a-Rojas, Carlos M.; Joseph‐Nathan, Pedro

doi:10.1021/jo00005a050

Cited by 23 publications

(38 citation statements)

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“…The conversion of 3 into 7 may involve carbocation A + generated by Lewis acid coordination at the C-9 hydroxy group of 3 followed by migration of the C-4–C-10 bond to form the C-4–C-9 bond. Elimination of a proton from the C-14 methyl group may generate the exocyclic methylene of 7 by analogy to a reported transformation . Similarly, a plausible route for the transformation of 3 into 8 (Scheme ) would include the initial mesylation at C-9 and C-13.…”

Section: Resultsmentioning

confidence: 97%

“…The COSY plot showed a correlation of H-14b with H-11 at δ 3.29. The NMR data of 7 were related to those of a moreliene derivative that has hydroxy groups at C-7 and C-8 instead of C-13 …”

Section: Resultsmentioning

confidence: 99%

“…It is known that the degree of functionalization and stereochemistry of the functional groups present in the longipinane skeleton are decisive in directing the rearrangements toward the six- or the seven-membered ring. This allows rearrangements in highly functionalized longipinanes to generate various novel skeletons and provide valuable information about their chemical behavior, which is very useful for the design of new synthetic strategies. − …”

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confidence: 99%

“…The NMR data of 7 were related to those of a moreliene derivative that has hydroxy groups at C-7 and C-8 instead of C-13. 5 Compound 8 showed its molecular composition as C 16 H 24 O 4 S by HRESIMS that gave the [M + Na] + ion at m/z 335.1291 (calcd as 335.1287 for C 16 H 24 O 4 SNa + ). Its 1 H NMR spectrum displayed characteristic signals for an exocyclic methylene at δ 5.08 (br s, H-14a) and 5.02 (q, J = 1.0 Hz) for H-14b coupled with H-11 at δ 3.25 (m), H-9 at δ 2.65 (m), and H-5 at δ 2.08 (br s).…”

mentioning

confidence: 99%

“…Elimination of a proton from the C-14 methyl group may generate the exocyclic methylene of 7 by analogy to a reported transformation. 5 Similarly, a plausible route for the transformation of 3 into 8 (Scheme 4) would include the initial mesylation at C-9 and C-13. The mesylate at C-9 is expelled by a C-4−C-10 bond migration to form the C-4−C-9 bond, and the carbocation formed at C-10 (K + ) stabilizes by eliminating a proton from the C-14 methyl group to provide the exocyclic methylene of 8.…”

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confidence: 99%

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Novel Sesquiterpenoid Skeletons by Wagner–Meerwein Rearrangements of Longipinane-9,13-diol-1-one Derivatives

et al. 2021

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The partial or total hydrolysis of (3R,4S,5S,6S,9R,10R,11R)-9,13-diangeloyloxylongipinan-1-one (1), isolated from the roots of Stevia viscida, gave alcohols 2 or 3, respectively, which were subjected to molecular rearrangements with boron trifluoride etherate. Compound 2 afforded (3R,4R,5R,6S,9R,10S,11S)-11,13-oxyneomorelian-1-one (10) and (4S,5R,6S,8S,10R)-10,13-oxyneojiquilp-2-en-1-one (11), both possessing novel sesquiterpenoid skeletons. In turn, 3 provided (3R,4R,5S,6S,9R,11R)-13-hydroxymoreli-10(14)-en-1-one (7) and 10. Acetylation of 3 gave 4, thus allowing reduction of the C-1 carbonyl group to yield 5, which was rearranged to (1S,3R,4S,5S,6S,9R,10R,11R)-13-acetoxy-9,11-epoxyjiquilpane (6), while an attempt to mesylate 3 directly gave rearranged (3R,4R,5S,6S,9R,11R)-13-mesyloxymoreli-10(14)-en-1-one (8) through expulsion of the C-9 mesylate group by the antiperiplanar C-4–C-10 bond migration to C-4–C-9. In addition, treatment of 1 with boron trifluoride etherate generated (3R,4R,5S,6S,9R,11R)-13-angeloyloxymoreli-10(14)-en-1-one (9). The structures of 2–11 were elucidated by 1D and 2D NMR experiments and those of 2, 3, 8, 10, and 11 were confirmed by single-crystal X-ray diffraction analysis.

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Section: Resultsmentioning

confidence: 97%

“…The COSY plot showed a correlation of H-14b with H-11 at δ 3.29. The NMR data of 7 were related to those of a moreliene derivative that has hydroxy groups at C-7 and C-8 instead of C-13 …”

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Novel Sesquiterpenoid Skeletons by Wagner–Meerwein Rearrangements of Longipinane-9,13-diol-1-one Derivatives

et al. 2021

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Wagner‐Meerwein Rearrangement

2010

Comprehensive Organic Name Reactions and Reagents

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The class of 1,2‐rearrangement of carbocation intermediates, from which the migratory group rearranges from an adjacent carbon atom to the carbocation center to form a more stable carbocation or to alleviate the ring strain, is generally known as the Wagner–Meerwein rearrangement. The Wagner–Meerwein rearrangement is generally observed in fused cyclic compounds, such as bicyclic terpene systems. In general, this rearrangement can be initiated under different conditions, which promote the generation of carbocation intermediates. However, due to the carbocationic nature of the rearrangement, this rearrangement sometimes leads to a complicated mixture of products. The modifications for this reaction include the photolysis, thermolysis of azo ‐compounds, and radical initiation of epoxide by Cp 2 TiCl and azo ‐compound by triphenyl pyrylium tetrafluoroborate. This reaction has been broadly applied in organic synthesis.

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Rearrangements of alcohols, phenols, diols and peroxides

Schneider¹

1993

PATAI'S Chemistry of Functional Groups

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Wagner-Meerwein rearrangements of longipinane derivatives

Cited by 23 publications

References 3 publications

Novel Sesquiterpenoid Skeletons by Wagner–Meerwein Rearrangements of Longipinane-9,13-diol-1-one Derivatives

Novel Sesquiterpenoid Skeletons by Wagner–Meerwein Rearrangements of Longipinane-9,13-diol-1-one Derivatives

Wagner‐Meerwein Rearrangement

Rearrangements of alcohols, phenols, diols and peroxides

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