In organic chemistry, carbonyl allylation describes methods for adding an allyl anion to an aldehyde or ketone to produce a homoallylic alcohol. [1] The carbonyl allylation was first reported in 1876 by Alexander Zaitsev and employed an allylzinc reagent. [2]
In 1978, Hoffmann reported the first asymmetric carbonyl allylation using a chiral allylmetal reagent, an allylborane derived from camphor. [3] [4] Such methods utilize preformed allyl metal reagents. The approach is well developed using allyl boranes [5]
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As illustrated by the Keck allylation, [6] catalytic enantioselective additions of achiral allylmetal reagents to carbonyl compounds also are possible by organostannane additions. [7]
Allylic boronate and -borane reagents have also been developed for enantioselective addition to carbonyls—in this class of reactions, the allylic boron reagent confers stereochemical control [5]
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In 1991, Yamamoto disclosed the first catalytic enantioselective method for carbonyl allylation, which employed a chiral boron Lewis acid-catalyst in combination with allyltrimethylsilane. [8] Numerous other catalytic enantioselective methods for carbonyl allylation followed. [9] [6] Catalytic variants of the Nozaki-Hiyama-Kishi reaction represent an alternative method for asymmetric carbonyl allylation, but stoichiometric metallic reductants are required. [10]
Whereas the aforementioned asymmetric carbonyl allylations rely on preformed allylmetal reagents, the Krische allylation exploits allyl acetate for enantioselective carbonyl allylation. [11] Selected methods for asymmetric carbonyl allylation are summarized below.
Carbonyl allylation has been employed in the synthesis of polyketide natural products and other oxygenated molecules with a contiguous array of stereocenters. For example, allylstannanation of a threose-derived aldehyde affords the macrolide antascomicin B, which structurally resembles FK506 and rapamycin, and is a potent binder of FKBP12. [12] The Krische allylation was used to prepare the polyketide (+)-SCH 351448, a macrodiolide ionophore bearing 14 stereogenic centers. [13]
In organic chemistry, carbonyl allylation describes methods for adding an allyl anion to an aldehyde or ketone to produce a homoallylic alcohol. [1] The carbonyl allylation was first reported in 1876 by Alexander Zaitsev and employed an allylzinc reagent. [2]
In 1978, Hoffmann reported the first asymmetric carbonyl allylation using a chiral allylmetal reagent, an allylborane derived from camphor. [3] [4] Such methods utilize preformed allyl metal reagents. The approach is well developed using allyl boranes [5]
(13)
As illustrated by the Keck allylation, [6] catalytic enantioselective additions of achiral allylmetal reagents to carbonyl compounds also are possible by organostannane additions. [7]
Allylic boronate and -borane reagents have also been developed for enantioselective addition to carbonyls—in this class of reactions, the allylic boron reagent confers stereochemical control [5]
(13)
In 1991, Yamamoto disclosed the first catalytic enantioselective method for carbonyl allylation, which employed a chiral boron Lewis acid-catalyst in combination with allyltrimethylsilane. [8] Numerous other catalytic enantioselective methods for carbonyl allylation followed. [9] [6] Catalytic variants of the Nozaki-Hiyama-Kishi reaction represent an alternative method for asymmetric carbonyl allylation, but stoichiometric metallic reductants are required. [10]
Whereas the aforementioned asymmetric carbonyl allylations rely on preformed allylmetal reagents, the Krische allylation exploits allyl acetate for enantioselective carbonyl allylation. [11] Selected methods for asymmetric carbonyl allylation are summarized below.
Carbonyl allylation has been employed in the synthesis of polyketide natural products and other oxygenated molecules with a contiguous array of stereocenters. For example, allylstannanation of a threose-derived aldehyde affords the macrolide antascomicin B, which structurally resembles FK506 and rapamycin, and is a potent binder of FKBP12. [12] The Krische allylation was used to prepare the polyketide (+)-SCH 351448, a macrodiolide ionophore bearing 14 stereogenic centers. [13]