Beilstein J. Org. Chem.2021,17, 1096–1140, doi:10.3762/bjoc.17.86
enantiomerically pure compound 54 after column chromatographic purification. Selective desulfinylation of 54 was carried out by using 1.0 M HCl in EtOAc, and further removal of the Tr group by the employment of TFA in dichloromethane afforded the 2-oxoindolinyl amino ester derivative 55, the key intermediate for
proceeded with high levels of diastereocontrol. The resulting sulfonamide derivatives 95 were transformed into the target spiro compound 97 by performing successive desulfinylation and intramolecular palladium-catalyzed N-arylation. To rationalize the stereochemical course of the addition, DFT calculations
the Re face of the imine with S configuration at the sulfur atom, through a chelated transition state. The reaction of chiral aldimine (SS)-104b with pentylmagnesium bromide gave compound 106 in 75% yield. Further successive N-desulfinylation, intramolecular palladium-catalyzed N-arylation, and final
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Graphical Abstract
Scheme 1:
General strategy for the enantioselective synthesis of N-containing heterocycles from N-tert-butane...
Beilstein J. Org. Chem.2017,13, 1513–1517, doi:10.3762/bjoc.13.150
applied successfully to the conversion of sulfinyl-substituted cyclopropylcarboxylates into the corresponding alcohols. The presence of sulfinyl substituents in the α-position to the carboxylate group caused a desulfinylation product formation with full regio- and stereoselectivity, instead of a carbonyl
group reduction. Investigations performed on different α-sulfinylcarbonyl compounds revealed that phenylsilane treatment constitutes a regiospecific method for the desulfinylation of a-sulfinylesters; for corresponding ketones the reaction course depends on the character of the carbonyl group.
Keywords
: desulfinylation; phenylsilane; reduction; regioselectivity; α-sulfinylesters; Introduction
The conversion of carboxylic acid derivatives to the corresponding alcohols is one of the fundamental processes in organic synthesis. Over the past decades, many reagents and conditions for this transformation have been
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Graphical Abstract
Scheme 1:
Different behaviour of cyclopropylphosphonates in the reaction with phenylsilane.