- Zn-Mediated Hydrodeoxygenation of Tertiary Alkyl Oxalates
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Herein we describe a general, mild, and scalable method for hydrodeoxygenation of readily accessible tertiary alkyl oxalates by Zn/silane under Ni-catalyzed conditions. The reduction method is suitable for an array of structural motifs derived from tertiary alcohols that bear diverse functional groups, including the synthesis of a key intermediate en route to estrone.
- Ye, Yang,Ma, Guobin,Yao, Ken,Gong, Hegui
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supporting information
p. 1625 - 1628
(2021/01/18)
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- Total synthesis with a chirogenic opening move demonstrated on steroids with estrane or 18a-homoestrane skeleton
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A concept of first choice for the synthesis of the title compounds had been proposed by Dane in the late 1930s. It was soon turned down, because the opening move - a chirogenic Diels-Alder reaction - did not work. With Lewis acids as mediators, however, a successful start has been achieved now. With Ti complexes of chelating ligands (Seebach's TADDOLs (= α,α,α',α'-tetraaryl-1,3-dioxolane-4,5-dimethanols)), enantioselective formation of the desired adducts does occur. Efficient total syntheses of 2 and 3a have been accomplished.
- Quinkert,Del Grosso,Doring,Doring,Schenkel,Bauch,Dambacher,Bats,Zimmermann,Durner
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p. 1345 - 1391
(2007/10/02)
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- An Enantioselective Version of the AB + D --> ABCD-Type Stereoid Total Synthesis
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Diene 1 and dienophile 4a in a Diels/Alder reaction mediated by a chiral ligand-modified Lewis acid enantioselectively furnish adduct 5a (chem. yield: 64percent; e.e: 73percent), which after partial deoxygenation and final enantioselection by recrystallization affords 5b.The latter compound can easily be converted via Torgov's pentaenone 6a into estrogens or progestogens. Key Words: stereoid total synthesis, enantioselective Lewis acid-mediated Diels/Alder reaction
- Quinkert, Gerhard,Grosso, Michael del,Bucher, Astrid,Bauch, Markus,Doering, Wolfgang,et al.
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p. 3617 - 3620
(2007/10/02)
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- A Synthesis of (+/-)-Estrone Methyl Ether via the Tandem Cope-Claisen Rearrangement
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A synthesis of (+/-)-estrone methyl ether (7b) is described that employs a new approach to the construction of the estrogen skeleton invoking the tandem Cope-Claisen rearrangement.
- Ziegler, Frederick E.,Lim, Hong
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p. 5229 - 5230
(2007/10/02)
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- TANDEM MICHAEL-MICHAEL-RING CLOSURE (MIMIRC) REACTIONS; ONE-POT STEROID TOTAL SYNTHESIS-(+/-)-9,11-DEHYDROESTRONES
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A new sequence of reactions involving tandem Michael-Michael-ring closure (MIMIRC) has been developed for efficient formation of three C-C bonds in one reaction vessel.The terminal ring closure reaction proceeds via either a 1,3- or a 1,6-cyclization, and this methodology also serves for construction of quaternary C centers.The usefulness of MIMIRC reactions is demonstrated by efficient assembly of cyclopropyl ketones and of trans-1-hydrindanones such as (+/-)-9,11-dehydroestrone 1b.This one-pot approach represents the shortest known convergent total synthesis of a steroid, and subsequent straightforward transformations lead directly to natural (+/-)-estrone.
- Posner, Gary H.,Mallamo, John P.,Black, Alison Y.
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p. 3921 - 3926
(2007/10/02)
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- 7,7A-Dihydro-4-[2-(3-alkoxyphenyl)-2-hydroxyethyl]-7a-alkyl-1, 5(6H)-indandiones,3,4,8,8a-tetrahydro-5-[2-(3-alkoxyphenyl)-2-hydroxyethyl]-8a-alkyl-1,6(7H)-naphthalenediones and processes for the preparation thereof utilizing asymmetric induction
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A multi-step, stereospecific total synthesis of steroids is disclosed. The starting materials for this process are the relatively inexpensive and readily available m-alkoxy acetophenones. The process is suitable for the preparation of racemic or optically
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