Facile synthesis of cis-2-Alkyl-3-trialkylsilyloxycycloalkanones via the non-aldol aldol rearrangement of 2,3-epoxycycloalkanols.
نویسندگان
چکیده
Silyl triflate-promoted rearrangement of cis-2,3-epoxycycloalkanols A, prepared by epoxidation of the cyclic allylic alcohol and then silylation, afforded good yields ( approximately 70-75%) of the cis-2-alkyl-3-silyloxycycloalkanones B, presumably via the intermediates C and D, even with quite large alpha-substituents, e.g., tert-butyl. Finally, it has been shown that the stereochemistry of the epoxy alcohol is crucial as one would expect from the mechanism.
منابع مشابه
Asymmetric synthesis of 1H-pyrrol-3(2H)-ones from 2,3-diketoesters by combination of aldol condensation with benzilic acid rearrangement.
An efficient two-step protocol for the asymmetric synthesis of 1H-pyrrol-3(2H)-one derivatives in 99% ee from conveniently accessed 2,3-diketoesters has been developed.
متن کاملFacile synthesis of novel D-ring modified steroidal dienamides via rearrangement of 2H-pyrans.
A simple and practical method for synthesis of the D-ring modified steroidal dienamides (4a-k) from the steroidal α,α-dicyanoalkene 3 and aldehydes via vinylogous aldol reaction was first reported. By using NaOAc as a base, the desired products were obtained in moderate to good yields in ethanol under mild conditions. All the synthesized steroidal dienamides are new and are currently being eval...
متن کاملUnexpected syn hydride migration in the non-aldol aldol reaction.
[structure: see text] Non-aldol aldol rearrangement of the epoxy silyl ether 13b afforded the expected anti methyl ketone 14, while the diastereomeric epoxy silyl ether 13a afforded the syn methyl ketone 8b via an unprecedented syn hydride migration. Calculations suggest that this unusual reaction proceeds via the carbocation, which cannot easily rotate due to steric hindrance.
متن کاملFacile creation of 3-substituted-3-hydroxy-2-oxindoles by arginine-catalyzed aldol reactions of α,β-unsaturated ketones with isatins.
An efficient approach for the synthesis of 3-substituted-3-hydroxy-2-oxindoles has been achieved via an aldol reaction of α,β-unsaturated ketones and isatins using arginine as an organocatalyst. A range of 3-substituted-3-hydroxy-2-oxindoles were obtained in moderate to high (up to 99%) yields. These 3-substituted-3-hydroxy-2-oxindoles with an additional enone moiety provide an opportunity for ...
متن کاملA tandem non-aldol aldol Mukaiyama aldol reaction.
[reaction: see text] A new one-pot tandem aldol process is described in which a secondary epoxy silyl ether is converted into the 1,5-bis-silyloxy-3-alkanone in good yield. Thus, treatment of the epoxy silyl ether 8 with TBSOTf and base affords the silyl enol ether 9 via non-aldol aldol rearrangement and addition of benzaldehyde and TBSOTf gives the ketone 10 with 4:1 syn selectivity. The diast...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Organic letters
دوره 10 10 شماره
صفحات -
تاریخ انتشار 2008