Alkylation of stabilized acetylides in DMSO. Preparation of α,β-acetylenic alcohols and acetals.

Chong, J. Michael; Wong, Susanna

doi:10.1016/s0040-4039(00)85233-8

Cited by 21 publications

(5 citation statements)

References 15 publications

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“…8 Deprotonation of 7 with methyllithium, followed by addition on n-amyl bromide in dimethyl sulfoxide (DMSO), led to 8. 9 Methyl ether cleavage with BBr 3 was successful; however, rapid quenching of the reaction with aqueous NaHCO 3 and ice was necessary in order to suppress the formation of byproducts. The air-sensitive resorcinol product was immediately protected as bis(ethoxyethyl) species 9 (EE ) 2-ethoxyethyl).…”

Section: Synthesismentioning

confidence: 99%

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Unsaturated Side Chain β-11-Hydroxyhexahydrocannabinol Analogs

et al. 1996

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The cannabinoid side chain is a key pharmacophore in the interaction of cannabinoids with their receptors (CB1 and CB2). To study the stereochemical requirements of the side chain, we synthesized a series of cannabinoids in which rotation around the C1'-C2' bond is blocked. The key steps in the synthesis were the cuprate addition of a substituted resorcinol to (+)-apoverbenone, the TMSOTf-mediated formation of the dihydropyran ring, and the stereospecific introduction of the beta-11-hydroxymethyl group. All the analogs tested showed nanomolar affinity for the receptors, the cis-hept-1-ene side chain having the highest affinity for CB1 (Ki = 0.89 nM) and showing the widest separation between CB1 and CB2 affinities. The parent n-heptyl-beta-11-hydroxyhexahydrocannabinol was the least potent binding to CB1 (Ki = 8.9 nM) and had the lowest selectivity between CB1 and CB2.

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Section: Synthesismentioning

confidence: 99%

“…Alkyne 7 was obtained via the enol phosphate . Deprotonation of 7 with methyllithium, followed by addition on n -amyl bromide in dimethyl sulfoxide (DMSO), led to 8 …”

Section: Synthesismentioning

confidence: 99%

Unsaturated Side Chain β-11-Hydroxyhexahydrocannabinol Analogs

et al. 1996

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“…This route takes advantage of organozinc chemistry developed by Knochel . The commercially available propiolaldehyde diethyl acetal 41 was monoalkylated with 1-chloro-3-iodopropane, yielding 42 …”

Section: Scope and Limitationsmentioning

confidence: 99%

Remote Stereochemical Control of Both Reacting Centers in Ketyl-Olefin Radical Cyclizations: Involvement of a Samarium Tridentate Ligate

1997

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High diastereoselection in a samarium(II) iodide-promoted ketyl-olefin cyclization reaction has been achieved using tartramide-derived keto allylic acetals as chiral auxiliaries. The unique features of the reaction include the fact that remote diastereoselection is achieved in a radical process and that high levels of stereochemical induction are observed at both new stereocenters created in the transformation. The source of the asymmetric induction is postulated to be a highly ordered, tricyclic transition structure made possible by three-point chelation between the ketyl intermediate and the samarium counterion. As such, this transformation also demonstrates the first example of the use of a chelating metal to affect high levels of remote asymmetric induction in a radical reaction. Because of this chelation, the sense of relative stereoselectivity is unusual for a SmI 2 -mediated cyclization, providing consistently high ratios of cis/trans isomers. A double-diastereodifferentiating experiment provides additional support for this mechanistic hypothesis. The preparation of enantiomerically enriched cyclopentanediols and -lactols can be achieved through this novel asymmetric cyclization protocol.

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“…10 The dienyl iodide 6 was prepared from aldehyde 3 11 through a sequence of propenyl additions, followed by acetylation (4), elimination (5), and conversion of the acetate to iodide 6 as depicted in Scheme 1.…”

mentioning

confidence: 99%

“…The synthesis of diene-tethered α-acetylenic acetal 1 and 2 was accomplished from the coupling reaction of 7 or 8 with dienyl iodide 6 , using the method reported by Chong . The dienyl iodide 6 was prepared from aldehyde 3 through a sequence of propenyl additions, followed by acetylation ( 4 ), elimination ( 5 ), and conversion of the acetate to iodide 6 as depicted in Scheme .…”

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confidence: 99%

Intramolecular Ionic Diels−Alder Reactions of α-Acetylenic Acetals

Shim

Yoo

et al. 2004

J. Org. Chem.

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The intramolecular ionic Diels-Alder reaction of alpha-acetylenic acetals as a precursor of the propargyl cation has been investigated in the presence of Lewis acids and in protic acids. The reaction of diene-tethered alpha-acetylenic acetals (1-2) with formic acid yielded the regioselective intramolecular ionic Diels-Alder reaction products, bicyclodienal (9) and bicyclodienone (11) derivatives, in good yields.

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Alkylation of stabilized acetylides in DMSO. Preparation of α,β-acetylenic alcohols and acetals.

Cited by 21 publications

References 15 publications

Unsaturated Side Chain β-11-Hydroxyhexahydrocannabinol Analogs

Unsaturated Side Chain β-11-Hydroxyhexahydrocannabinol Analogs

Remote Stereochemical Control of Both Reacting Centers in Ketyl-Olefin Radical Cyclizations: Involvement of a Samarium Tridentate Ligate

Intramolecular Ionic Diels−Alder Reactions of α-Acetylenic Acetals

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