New Synthesis of 18-Norestradiol

Kühl, Alexander; Karels, Heiko; Kreiser, Wolfgang

doi:10.1002/(sici)1522-2675(19990113)82:1<30::aid-hlca30>3.0.co;2-t

Cited by 6 publications

(2 citation statements)

References 18 publications

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“…Repetition of the RCM reaction on compound 6 g (see Supporting Information) allowed for the formation of 19 (this compound has been previously prepared by a lengthy degradation of estradiol itself). Because compound 19 has been transformed into 18‐nor‐estradiol in two steps, [18] our synthetic work constitutes a formal synthesis of this unnatural steroidal analogue whose congeners have been reported to possess interesting biological activity. [ 19a , 19b , 19c , 19d , 19e ] In this regard, it is interesting to note the stereoselective hydroboration reaction [18] of 17 , using conditions reported in the literature.…”

Section: Resultsmentioning

confidence: 99%

“…Because compound 19 has been transformed into 18‐nor‐estradiol in two steps, [18] our synthetic work constitutes a formal synthesis of this unnatural steroidal analogue whose congeners have been reported to possess interesting biological activity. [ 19a , 19b , 19c , 19d , 19e ] In this regard, it is interesting to note the stereoselective hydroboration reaction [18] of 17 , using conditions reported in the literature. In our hands, 17 gave the two syn addition products exclusively, in a 61 : 39 ratio, with the major product 18 possessing the desired trans 6,5‐ring junction.…”

Section: Resultsmentioning

confidence: 99%

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Alcohols as Efficient Intermolecular Initiators for a Highly Stereoselective Polyene Cyclisation Cascade

Aynetdinova

Jacques

Christensen

et al. 2023

Chemistry A European J

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The use of benzylic and allylic alcohols in HFIP solvent together with Ti(OiPr)4 has been shown to trigger a highly stereoselective polyene cyclisation cascade. Three new carbon‐carbon bonds are made during the process and complete stereocontrol of up to five new stereogenic centers is observed. The reaction is efficient, has high functional group tolerance and is atom‐economic generating water as a stoichiometric by‐product. A new polyene substrate‐class is employed, and subsequent mechanistic studies indicate a stereoconvergent mechanism. The products of this reaction can be used to synthesize steroid‐analogues in a single step.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Alcohols as Efficient Intermolecular Initiators for a Highly Stereoselective Polyene Cyclisation Cascade

Aynetdinova

Jacques

Christensen

et al. 2023

Chemistry A European J

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Beckmann Rearrangement and Beckmann Fragmentation

2010

Comprehensive Organic Name Reactions and Reagents

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The rearrangement of an oxime to its corresponding amide in the presence of an acid and is generally known as the Beckmann rearrangement. The oxime is also formed by the reaction of a ketone with hydroxylamine. The conversion of cyclohexanone oxime into e‐caprolactam is known to be an important component for the fabrication of nylon 6. The Beckmann rearrangement of oxime derivatives proceeds stereospecifically, and the stereo‐configuration of the migrating group is retained. This rearrangement has been applied to the construction of a variety of nitrogen‐containing compounds. Certain oximes, those having a quarternary carbon anti to the hydroxyl, have been reported to undergo the rearrangement to form nitriles instead of amides. This type of transformation is called the Beckmann fragmentation, which has been used in modification of steroids. Other oximes, such as the bridged bicyclic ketoximes and oximes with an electron‐donating substituent at the α‐carbon, also undergo fragmentation.

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