Annelation of 2,3-dimethylcyclohexanone. Synthetic proof for the stereochemistry of the sesquiterpene aristolone

Piers, Edward; Britton, Ronald W.; Waal, William De

doi:10.1139/v69-714

Cited by 29 publications

(1 citation statement)

References 4 publications

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“…The synthesis of 22 has been reported (26) 'Attempting to form 16 using methyllithium instead of the Grignard gave only the carbinol i and unreacted 20. Similar results were obtained under a variety of conditions with the ethylene ketal of 19 and the corresponding ketalmethyl ester (25).…”

Section: Ysupporting

confidence: 79%

Approaches to the Synthesis of Triterpenoids. II. Some Tetracyclic Precursors Suitable for Conversion into Pentacyclic Triterpenoids

ApSimon¹,

Baker²,

Buccini³

et al. 1972

Can. J. Chem.

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The stereoselective total synthesis of several partially reduced chrysene derivatives, suitable as precursors for a variety of triterpenoids, is described. The key reaction in the most efficient route involves the highly stereoselective reductive alkylation of a cyclic a$-unsaturated ketone with ally1 bromide in lithium-ammonia, using water as a proton donor.La synthtse totale et stertoselective de plusieurs derivts partiellement reduits du chrysene est dtcrite; ces dtrivts sont utilists en tant que precurseurs d'un certain nombre de composts triterpeniques. La rtaction cruciale, par la methode la plus efficace, implique une alkylation par reduction hautement sttrtoselective d'une cttone a$-insaturte par le bromure d'allyle dans un melange lithium-ammoniaque et en utilisant I'eau comme source de protons.

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Section: Ysupporting

confidence: 79%

Approaches to the Synthesis of Triterpenoids. II. Some Tetracyclic Precursors Suitable for Conversion into Pentacyclic Triterpenoids

ApSimon¹,

Baker²,

Buccini³

et al. 1972

Can. J. Chem.

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Conjugate Addition Reactions of Organocopper Reagents

Posner

2011

Organic Reactions

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Addition of an organometallic reagent to alpha,beta‐usaturated carbonyl compounds occurs in one or both of two modes: attack at the carbonyl function produces a 1,2 adduct, whereas reaction with the entire system gives a 1,4 adduct. Organoalkali metal reagents derived from unstabilized carbanions generally add across the carbonyl group, where as enolate and other stabilized anions usually undergo a Michael addition, introducing a carboalkyl group at the beta carbon. Grignard reagents normally give 1,2 adducts. The wide scope of these reagents has made conjugate addition of alkyl and aryl groups a useful reaction in organic synthesis. Copper‐promoted conjugate additions were generally effected by allowing an organomagnesium reagent and a alpha, beta‐ unsaturated carbonyl compound to react in the presence of a catalytic amount of copper salt. Studies since 1966 have shown that stoichiometric organocopper reagents in addition to their broad utility in coupling reactions with organic halides and in reaction with other substrates undergo unusually effective conjugate addition to a wide variety alpha,beta‐ unsaturated carbonyl substrates. Emphasis in this chapter is on stoichiometric organic copper reagents. Mechanism, scope, limitations, synthetic utility, and optimal conditions are considered.

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Reduction and Related Reactions of α,β‐Unsaturated Carbonyl Compounds with Metals in Liquid Ammonia

Caine

2011

Organic Reactions

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This chapter is concerned with the reduction and related reactions of alpha,beta‐unsaturated ketones by alkali and alkaline earth metals in liquid ammonia. Upon treatment with a metal in liquid ammonia (usually containing an ether co‐solvent) a simple alpha, beta‐unsaturated ketone is converted into the metal enolate corresponding to the saturated ketone. Research during the first half of the 20 th Century revealed that a variety of organic compounds undergo reduction with metals in liquid ammonia but preparative metal‐ammonia reductions of alpha,beta‐unsaturated carbonyl compounds were apparently not described until 1951. In addition to affording a remarkable degree of stereoselectivity, many metal‐ammonia reductions of unsaturated carbonyl systems can be preformed in a variety of functional and protective groupings and the reaction is generally free of the rearrangements sometimes observed when chemical reduction methods are used. The unique features of metal‐ammonia reductions and related reaction have led to their wide application in total synthesis and transformations.

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Annelation of 2,3-dimethylcyclohexanone. Synthetic proof for the stereochemistry of the sesquiterpene aristolone

Cited by 29 publications

References 4 publications

Approaches to the Synthesis of Triterpenoids. II. Some Tetracyclic Precursors Suitable for Conversion into Pentacyclic Triterpenoids

Approaches to the Synthesis of Triterpenoids. II. Some Tetracyclic Precursors Suitable for Conversion into Pentacyclic Triterpenoids

Conjugate Addition Reactions of Organocopper Reagents

Reduction and Related Reactions of α,β‐Unsaturated Carbonyl Compounds with Metals in Liquid Ammonia

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