Catalytic protodeboronation of pinacol boronic esters: formal anti-Markovnikov hydromethylation of alkenes

Pinacol boronic esters are highly valuable building blocks in organic synthesis. In contrast to the many protocols available on the functionalizing deboronation of alkyl boronic esters, protodeboronation is not well developed. Herein we report catalytic protodeboronation of 1°, 2° and 3° alkyl boron...

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Bibliographic Details
Published inChemical science (Cambridge) Vol. 1; no. 24; pp. 621 - 6214
Main Authors Clausen, Florian, Kischkewitz, Marvin, Bergander, Klaus, Studer, Armido
Format Journal Article
LanguageEnglish
Published CAMBRIDGE Royal Soc Chemistry 28.06.2019
Royal Society of Chemistry
Subjects
Alkenes
Catalysis
Chemistry
Chemistry, Multidisciplinary
Cholesterol
Esters
Homology
Physical Sciences
Science & Technology
HYDROBORATION
COUPLING REACTIONS
CONVERSION
SECONDARY
POLAR CROSSOVER REACTIONS
CONVENIENT
PROTONOLYSIS
INVERSION
SATURATED COMPOUNDS
ORGANOBORANES
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Summary:Pinacol boronic esters are highly valuable building blocks in organic synthesis. In contrast to the many protocols available on the functionalizing deboronation of alkyl boronic esters, protodeboronation is not well developed. Herein we report catalytic protodeboronation of 1°, 2° and 3° alkyl boronic esters utilizing a radical approach. Paired with a Matteson-CH 2 -homologation, our protocol allows for formal anti-Markovnikov alkene hydromethylation, a valuable but unknown transformation. The hydromethylation sequence was applied to methoxy protected (−)-Δ8-THC and cholesterol. The protodeboronation was further used in the formal total synthesis of δ-( R )-coniceine and indolizidine 209B. Methane is formally added to alkenes via sequential hydroboration, Matteson-CH 2 -homologation and radical protodeboronation.
Bibliography:Electronic supplementary information (ESI) available. See DOI
10.1039/c9sc02067e
ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
ISSN:2041-6520
2041-6539
DOI:10.1039/c9sc02067e