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Alkynyl ketones hydroboration

In the hydroboration of terminal alkenes, carrying a ketone or aldehyde group, with a variety of borane reagents, dicyclohexylborane has been identified as the most efficient reagent. Analogous hydroboration of alkynyl ketones and alkynyl aldehydes with dicyclohexylborane yields the corresponding olefinic carbonyl compounds after protonation, or dicarbonyl compounds after oxidation. ... [Pg.432]

Hydroboration of 1-bromo-l-alkynes with chloro(thexyl)-borane leads to the synthesis of alkynyl ketones in 61-63% yields by the sequence of reactions shown in eq 5. Sequential treatment of alkenylchloro(thexyl)boranes, which are formed by the reaction of chloro(thexyl)borane with alkynes, with lithium chloro-propargylide and aldehydes affords 1,3-enynols or 1,2,4-trienols depending on the reaction conditions. ... [Pg.145]

Another approach in the search for useful chiral reducing agents has been the derivatization of borane and boron hydrides [110, 111, 114]. Some of the most successful chiral reagents based on boron are those derived from the hydroboration of a-pinene, which is conveniently available in both enantiomeric forms (Scheme 2.22). Midland reported that the hydroboration product of a-pinene with 9-BBN, a reagent that subsequently came to be known as Alpine-Borane (179), is superb in the enantioselective reduction of aiyl alkynyl ketones [124]. He showcased the use of Alpine-Borane in the context of an enantioselective synthesis of Prelog-Djerassi lactone 181... [Pg.42]


See other pages where Alkynyl ketones hydroboration is mentioned: [Pg.27]    [Pg.799]    [Pg.315]    [Pg.147]    [Pg.60]    [Pg.17]    [Pg.424]    [Pg.132]    [Pg.275]   
See also in sourсe #XX -- [ Pg.432 ]

See also in sourсe #XX -- [ Pg.432 ]




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