Diastereoselective Reactions of gem-Bismetallic Derivatives

Wang, Fan; Tang, Jie; Labaudinière, L.; Marek, Ilane; Normant, Jean F.

doi:10.1055/s-1995-5048

Cited by 22 publications

(11 citation statements)

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“…In this case, the two diastereomers 44H/D and 44D/ H do not show interconversion under the experimental conditions. This result points to a configurational stability of these primary organozinc halides. , …”

Section: Diastereoselective Reactivity Of the Organo-gem-dimetallicsmentioning

confidence: 65%

“…151 Other electrophiles can be introduced with a lower diastereoselectivity which corroborate however the configurational stability of these dimetallics. For example sequential treatment of the bis anion 43H with deuteriomethanol and iodine leads to a predominant diastereomer, whereas the sequential treatment of the deuterated dianion 43D with hydrogenomethanol and iodine leads to the opposite predominant diastereomer (Scheme 108).…”

Section: + +mentioning

confidence: 76%

“…Whatever the mechanism of the formation of the organo- gem -dimetallic, the coordination of the oxygen atom to the metal m 1 is absolutely necessary to discriminate the reactivity of the two metals toward the first electrophile: without internal chelation, two diastereomers are obtained in approximatively equal amounts …”

Section: Diastereoselective Reactivity Of the Organo-gem-dimetallicsmentioning

confidence: 99%

“…It was considered that the carbon−metal bond reacts with retention of configuration with each electrophile as is usual in the case of nonallylic or nonbenzylic organometallics. See ref .…”

Section: Referencesmentioning

confidence: 99%

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Synthesis and Reactivity of sp³-Geminated Organodimetallics

1996

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Section: Diastereoselective Reactivity Of the Organo-gem-dimetallicsmentioning

confidence: 65%

Section: + +mentioning

confidence: 76%

Section: Diastereoselective Reactivity Of the Organo-gem-dimetallicsmentioning

confidence: 99%

Section: Referencesmentioning

confidence: 99%

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Synthesis and Reactivity of sp³-Geminated Organodimetallics

1996

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“…The coordination (or chelation) of the oxygen atom to the metal M 1 decreases the reactivity of the latter towards the first electrophile and thus, the non-chelated metal M 2 reacts preferentially with this electrophile. 20 Therefore, the addition of one equivalent of I 2 Scheme 2 leads to the unique reaction of the non-chelated metal M 2 to give the corresponding cyclopropyl zinc carbenoid 19 21 that subsequently reacts with the second electrophile such as H + to lead to 20 (Scheme 2). In such case, a single diastereoisomer is formed for the creation of three stereogenic centers in the reaction sequence (Scheme 2 and Table 2, entry 5).…”

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Cyclopropenyllithiums as a new source of 1,1-bismetalated cyclopropyl derivatives

Levin

Marek

2008

Chem. Commun.

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Preparation and Applications of Functionalized Organozinc Compounds

et al. 2001

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Organozinc compounds have been known for more than 150 years. With the exception of zinc enolates (Reformatsky reagents) and iodomethylzinc derivatives (Simmons‐Smith, Furukawa, and Sawada reagents), their synthetic potential has only been recently recognized. This is certainly due to their low reactivity and to the absence of general methods of preparation. Although the carbon‐zinc bond in diethylzinc has a dissociation energy of 34.5 kcal/mol, it has, because of the similar electronegativities of zinc and carbon, a highly covalent character (ca. 85 %), which is comparable to a carbon‐tin bond. The carbon‐zinc bond is therefore inert to moderately polar electrophiles such as aldehydes, ketones, esters, or nitriles. On the other hand, the presence of empty low‐lying p orbitals at the zinc center allows transmetallations with a number of transition metal complexes. This is favored for both kinetic and thermo‐dynamic reasons. The availability of d orbitals at the metal center in these compounds allows for new reaction pathways with electrophilic reagents that were not available for the corresponding zinc reagents. This reactivity has been exploited for the formation of new carbon‐carbon bonds and efficient cross‐coupling reactions between organozinc derivatives and unsaturated organic halides, as Negishi has demonstrated using catalytic amounts of palladium(0) salts. Similar catalytic processes have been reported with copper(I) and titanium(IV) complexes, which can mediate numerous reactions of organozinc reagents with organic electrophiles. The scope and synthetic applications of zinc organometallics were greatly extended when it was found that these species can accommodate a wide range of functional groups. They are ideally suited for the construction of polyfunctional organic molecules without the use of multiple protection and deprotection steps. Although some functionalized organozinc compounds bearing ester groups such had been reported, it was only recently that systematic studies have shown the synthetic potential of these reagents. This chapter describes methods for the preparation of functionalized organozinc halides, diorganozincs, and organozincates and their reactions with electrophilic reagents in the presence of transition metal catalysts, as well as synthetic applications demonstrating their synthetic utility for natural product synthesis. Only the preparation and reactivity of zinc organometallics bearing relatively reactive functional groups are covered. Thus, the chemistry of organozinc compounds bearing an ether, acetal, ketal, trialkylsilyl, or polyfluoroalkyl group is, in general, not covered.

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Diastereoselective Reactions of gem-Bismetallic Derivatives

Cited by 22 publications

References 0 publications

Synthesis and Reactivity of sp³-Geminated Organodimetallics

Synthesis and Reactivity of sp³-Geminated Organodimetallics

Cyclopropenyllithiums as a new source of 1,1-bismetalated cyclopropyl derivatives

Preparation and Applications of Functionalized Organozinc Compounds

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Diastereoselective Reactions of gem-Bismetallic Derivatives

Cited by 22 publications

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Synthesis and Reactivity of sp3-Geminated Organodimetallics

Synthesis and Reactivity of sp3-Geminated Organodimetallics

Cyclopropenyllithiums as a new source of 1,1-bismetalated cyclopropyl derivatives

Preparation and Applications of Functionalized Organozinc Compounds

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Synthesis and Reactivity of sp³-Geminated Organodimetallics

Synthesis and Reactivity of sp³-Geminated Organodimetallics