Generation and reactions of 2-lithio-2-substituted-1,3-benzodithioles; new, convenient acyl carbanion equivalents

Ncube, Smollie; Pelter, Andrew; Smith, Keith; Blatcher, Philip; Warren, Stuart

doi:10.1016/s0040-4039(01)91532-1

Cited by 32 publications

(7 citation statements)

References 10 publications

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“…The utility and versatility of this carbenium ion is fully realized when the simple elimination of the sulfur group is carried out with Ni‐Raney. In addition, the benzodithiol is a chameleonic group as it can also stabilize negative charges . The simple metalation followed by alkylation of this group can be used to access a variety of useful intermediates (Scheme ).…”

Section: Discussionmentioning

confidence: 99%

“…In addition, the benzodithiol is a chameleonic group as it can also stabilize negative charges. 42 The simple metalation followed by alkylation of this group can be used to access a variety of useful intermediates (Scheme 4). Alkylation of benzodithiol group is not only possible with alkyl bromides/ iodides, but also with epoxides and other electrophiles.…”

Section: Discussionmentioning

confidence: 99%

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A Practical and Stereoselective Organocatalytic Alkylation of Aldehydes with Benzodithiolylium Tetrafluoroborate

et al. 2014

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Recently, the direct substitution of allylic, benzylic, and tertiary alcohols has been achieved via SN 1-type reactions with catalytic amounts of Brønsted or Lewis acids. When a new stereogenic center is formed most of these transformations produce the desired product as a racemate, as these reactions proceed through carbenium ions. The arsenal of activation modes available in organocatalysis can be used to set up suitable reaction conditions in which chiral nucleophiles (enamine catalysis) or chiral electrophiles (iminium catalysis, chiral counterion catalysis) can easily be generated. Recently, we have used stabilized carbenium ions, directly available or obtained from the corresponding alcohols, in new organocatalytic stereoselective SN 1-type reactions. The commercially available carbenium ion benzodithiolylium tetrafluoroborate can be used for the straightforward organocatalytic stereoselective alkylation of aldehydes. In this account we will illustrate the application of this methodology in the total synthesis of natural products and the preparation of valuable starting materials.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A Practical and Stereoselective Organocatalytic Alkylation of Aldehydes with Benzodithiolylium Tetrafluoroborate

et al. 2014

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“…69 Similarly, 1,3-benzodithiolanes have been reported to interact with different electrophiles. 70 The racemic trans-disulfoxide of 1,3-dithiolanes can also be deprotonated and reacted with aldehydes with moderate to excellent diastereoselectivity.…”

Section: Silyl 13-dithiolanesmentioning

confidence: 99%

Synthesis and stereoselective functionalization of silylated heterocycles as a new class of formyl anion equivalents

Degl’Innocenti¹,

Pollicino²,

Capperucci³

2006

Chem. Commun.

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The fluoride ion-induced reactivity of a series of silyl heterocycles leads to the generation of nucleophilic species capable of interacting with electrophiles, thus disclosing new classes of formyl and acyl anion synthons. Moreover, when reacting stereodefined molecules, the stereoinformation of the reacting carbon-silicon bond is transferred to the newly formed carbon-carbon bond, suggesting possible applications in stereoselective synthesis. Thus, silyl dithiolanes, oxathiolanes, dioxolanes, thiazolidines and oxazolidines can be efficiently and stereoselectively functionalized under fluoride ion conditions in the presence of electrophiles. While direct access to silyl heterocycles is generally either prevented or troublesome, a novel protocol for their synthesis has also been developed, together with a simple general access route to several functionalized and stereodefined mercaptans, building blocks for the construction of silyl heterocycles.

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“…[13] The products obtained contain the benzodithiol group as a versatile building block [14] that can be easily transformed into the corresponding methyl group by treatment with Raney Ni or metallated by n-BuLi. [15] Herein, we report that stereoselective a-alkylation of benzylic aldehydes with benzodithiolylium tetrafluoroborate can be used to install the benzylic stereocentre in the synthesis of bisabolanes.…”

Section: Introductionmentioning

confidence: 99%

A Straightforward Organocatalytic Alkylation of 2‐Arylacetaldehydes: An Approach towards Bisabolanes

Gualandi¹,

Canestrari²,

Emer³

et al. 2014

Adv Synth Catal

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A highly stereoselective organocatalytic aalkylation of 2-arylacetaldehydes with a commercially available carbenium tetrafluoroborate is described. The stereoselective alkylation was carried out in acetonitrile/water, under air in the presence of a commercially available imidazolidinone (MacMillans catalyst). Key intermediates for the synthesis of bisa-bolanes were obtained through a simple chemistry. In particular a direct, enantioselective and facile synthesis of (R)-(À)-curcumene is described. Scheme 4. Reaction sequence for the synthesis of the key intermediates 13a-k. 530 Scheme 6. Synthesis of the iodides 16a-k. Scheme 7. Elongation by two carbons via reaction of iodides 16a-e with malonate ion and successive decarboxylation. Scheme 8. Published synthetic routes to bisabolanes starting from ester 18c.532

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Generation and reactions of 2-lithio-2-substituted-1,3-benzodithioles; new, convenient acyl carbanion equivalents

Cited by 32 publications

References 10 publications

A Practical and Stereoselective Organocatalytic Alkylation of Aldehydes with Benzodithiolylium Tetrafluoroborate

A Practical and Stereoselective Organocatalytic Alkylation of Aldehydes with Benzodithiolylium Tetrafluoroborate

Synthesis and stereoselective functionalization of silylated heterocycles as a new class of formyl anion equivalents

A Straightforward Organocatalytic Alkylation of 2‐Arylacetaldehydes: An Approach towards Bisabolanes

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