ISSN:
0170-2041
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Highly Selective Total Synthesis of 19-Nor-Steroids via a Photochemical Key Reaction: Racemic Target Compounds1,4)Ring A and ring D building blocks 17b and rac-15, easily available from m-cresyl methyl ether (19a) or (E)-1,4-dibromo-2-butene (13b) and methyl malonate (14a), respectively, react by Michael addition affording the key compound rac-9a. The latter compound by successive photoenolization, intramolecular Diels/Alder reaction, and dehydration furnishes the pretarget compounds rac-5 and rac-6. From here the 19-norsteroids rac-estrone (rac-1a), rac-19-norandrost-4-ene-3,17-dione (rac-2a), rac-estradiol-17β (rac-3a), and rac-19-nortestosterone (rac-4a) are optionally accessible (cf. schemes 1 and 2 as well as tables 3 and 4).
Notes:
Die Ring A- und Ring D-Bausteine 17b und rac-15, die bequem aus m-Kresolmethylether (19a) sowie (E)-1,4-Dibrom-2-buten (13b) und Malonsäure-dimethylester (14a) zugänglich sind, fügen sich in einer Michael-Addition zur Schlüsselverbindung rac-9a zusammen. Letztere reagiert nacheinander durch Photoenolisierung, intramolekulare Diels/Alder-Reaktion und Dehydratisierung zu den Präzielverbindungen rac-5 und rac-6. Von hier aus erhält man wahlweise die 19-Nor-Steroide rac-Östron (ra-1a), rac-19-Norandrost-4-en-3,17-dion (rac-2a), rac-Östradiol-17β (rac-3a) und rac-19-Nortestosteron (rac-4a) (s. Schemata 1 und 2 sowie Tab. 3 und 4).
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.198119811220
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