The stereoselective total synthesis of several partially reduced chrysene derivatives, suitable as precursors for a variety of triterpenoids, is described. The key reaction in the most efficient route involves the highly stereoselective reductive alkylation of a cyclic a$-unsaturated ketone with ally1 bromide in lithium-ammonia, using water as a proton donor.La synthtse totale et stertoselective de plusieurs derivts partiellement reduits du chrysene est dtcrite; ces dtrivts sont utilists en tant que precurseurs d'un certain nombre de composts triterpeniques. La rtaction cruciale, par la methode la plus efficace, implique une alkylation par reduction hautement sttrtoselective d'une cttone a$-insaturte par le bromure d'allyle dans un melange lithium-ammoniaque et en utilisant I'eau comme source de protons.
This paper is dedicated to Prof. Raymond U . Lemieux on the occasion of his 60th birthday SUZANNE R. MACAULAY. Can. J. Chem. 58, 2567Chem. 58, (1980. Isomerization of straight chain decyn-1-01s mediated by the sodium salt of 1,3-diaminopropane was studied as a function of time, temperature, and the initial position of the triple bond. At 50°C 9-decyn-1-01, the thermodynamically favoured isomer, was formed rapidly regardless of the initial position of the triple bond. At lower temperatures the appearance of intermediate isomers was observed. The homopropargylic isomer was found to be remarkably stable, and under suitable conditions, conversion of 2-to 3-decyn-1-01 was carried out in 68% isolated yield. SUZANNER. MACAULAY. Can. J. Chem. 58, 2567Chem. 58, (1980. On a etudie I'isom~risation des decynols-1 achaine linkaire en presence d'un sel de sodium du diamino-1,3 propane, en fonction du temps, de la temperature et de la position initiale de la triple liaison. A 50"C, I'isombre thermodynamiquement favorise, le dCcyn-9 01-I, se forme rapidement indkpendamment de la position de la triple liaison. A des tempkratures plus basses on observe la formation d'un isombre intermediaire. On a trouvk que I'isombre homopropargylique est remarquablement stable et dans des conditions convenables la transformation du decyn-2 01-1 en decyn-3 01-1 se fait avec un rendement de 68%.[Traduit par le journal] I
Das aus dem Tetralon (I) durch Grignard‐Reaktion mit Methyl‐MgJ in Benzol bei 25°C und Oxidation des entstehenden 1,5‐Din1ethyl‐6‐methoxy‐3 ,4‐dihydronaphthalins mit Monoperphthalsäure in Diäthyläther bei 5°C dargestellte β‐Tetralon (II) wird mit Äthylvinylketon in Gegenwart von NaOH in wäßrigem Methanol bei ‐5 bis 0°C, später 65°C, zum Tetrahydro‐H‐phenanthrenon (III) kondensiert.
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