Oxidative cyclization of iodo ketones. Synthesis of 6-oxa-5α-pregnane-3,20-dione

The steroidal δ- and γ-iodo ketones 1 and 9 were converted to the cyclic hemiketals 3 and 10, by oxidation to the iodoso derivatives with m-CPBA. Spontaneous cyclization of the latter intermediates to the corresponding oxocarbenium ions, followed by stereoselective addition of water, rendered the he...

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Autores principales: Nicoletti, D., Ghini, A.A., Burton, G.
Formato: JOUR
Materias:
pregnane derivative
article
drug synthesis
reaction analysis
stereochemistry
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00223263_v61_n19_p6673_Nicoletti
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_00223263_v61_n19_p6673_Nicoletti
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spelling todo:paper_00223263_v61_n19_p6673_Nicoletti2023-10-03T14:31:21Z Oxidative cyclization of iodo ketones. Synthesis of 6-oxa-5α-pregnane-3,20-dione Nicoletti, D. Ghini, A.A. Burton, G. pregnane derivative article drug synthesis reaction analysis stereochemistry The steroidal δ- and γ-iodo ketones 1 and 9 were converted to the cyclic hemiketals 3 and 10, by oxidation to the iodoso derivatives with m-CPBA. Spontaneous cyclization of the latter intermediates to the corresponding oxocarbenium ions, followed by stereoselective addition of water, rendered the hemiketals. Depending on the reaction conditions, the five-membered oxocarbenium ion derived from the γ-iodo ketone 9 may add H2O or m-CPBA to give either the hemiketal or a Baeyer-Villiger type product 12, while the oxocarbenium derived from 1 gives exclusively the hemiketal. When the reaction was carried out in dry methanol, methyl ketals were formed. Use of this methodology allowed us to synthesize 6-oxa-5α-pregnanes with and without functionalization at C-19. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00223263_v61_n19_p6673_Nicoletti
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic pregnane derivative
article
drug synthesis
reaction analysis
stereochemistry
spellingShingle pregnane derivative
article
drug synthesis
reaction analysis
stereochemistry
Nicoletti, D.
Ghini, A.A.
Burton, G.
Oxidative cyclization of iodo ketones. Synthesis of 6-oxa-5α-pregnane-3,20-dione
topic_facet pregnane derivative
article
drug synthesis
reaction analysis
stereochemistry
description The steroidal δ- and γ-iodo ketones 1 and 9 were converted to the cyclic hemiketals 3 and 10, by oxidation to the iodoso derivatives with m-CPBA. Spontaneous cyclization of the latter intermediates to the corresponding oxocarbenium ions, followed by stereoselective addition of water, rendered the hemiketals. Depending on the reaction conditions, the five-membered oxocarbenium ion derived from the γ-iodo ketone 9 may add H2O or m-CPBA to give either the hemiketal or a Baeyer-Villiger type product 12, while the oxocarbenium derived from 1 gives exclusively the hemiketal. When the reaction was carried out in dry methanol, methyl ketals were formed. Use of this methodology allowed us to synthesize 6-oxa-5α-pregnanes with and without functionalization at C-19.
format JOUR
author Nicoletti, D.
Ghini, A.A.
Burton, G.
author_facet Nicoletti, D.
Ghini, A.A.
Burton, G.
author_sort Nicoletti, D.
title Oxidative cyclization of iodo ketones. Synthesis of 6-oxa-5α-pregnane-3,20-dione
title_short Oxidative cyclization of iodo ketones. Synthesis of 6-oxa-5α-pregnane-3,20-dione
title_full Oxidative cyclization of iodo ketones. Synthesis of 6-oxa-5α-pregnane-3,20-dione
title_fullStr Oxidative cyclization of iodo ketones. Synthesis of 6-oxa-5α-pregnane-3,20-dione
title_full_unstemmed Oxidative cyclization of iodo ketones. Synthesis of 6-oxa-5α-pregnane-3,20-dione
title_sort oxidative cyclization of iodo ketones. synthesis of 6-oxa-5α-pregnane-3,20-dione
url http://hdl.handle.net/20.500.12110/paper_00223263_v61_n19_p6673_Nicoletti
work_keys_str_mv AT nicolettid oxidativecyclizationofiodoketonessynthesisof6oxa5apregnane320dione
AT ghiniaa oxidativecyclizationofiodoketonessynthesisof6oxa5apregnane320dione
AT burtong oxidativecyclizationofiodoketonessynthesisof6oxa5apregnane320dione
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