Recent studies on veratrum alkaloids: a new reaction of sodium triacetoxyborohydride [NaBH(OAc)3]

Saksena, Anil K.; Mangiaracina, Pietro

doi:10.1016/s0040-4039(00)81383-0

Cited by 183 publications

(54 citation statements)

References 4 publications

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“…David's regioselective bromineinduced oxidation of stannylene acetals [146] furnished ketone 217, and reduction with sodium triacetoxyborohydride [147] ensured intramolecular hydrogen delivery to give the desired C-4 orientation in 218. After regioselective silylation and methylation, the anomeric center of 219 was liberated, and use of the Levine reagent [148] paved the way to enol ether 220.…”

Section: From the Key Intermediate 204 To Reserpinementioning

confidence: 99%

Unsaturated Sugars: A Rich Platform for Methodological and Synthetic Studies

Fraser‐Reid¹,

López²

2009

COC

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Section: From the Key Intermediate 204 To Reserpinementioning

confidence: 99%

Unsaturated Sugars: A Rich Platform for Methodological and Synthetic Studies

Fraser‐Reid¹,

López²

2009

COC

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“…It is known that Na[B(OAc) 3 H] is converted to an alkoxy derivative such as Na[B(OAc) 2 (OR)H] in the presence of an alcohol and that the product might act as an improved hydride donor compared to the original species. 22 Exchanging the acetate ion with the alkoxide primarily occurs by addition of the hydride reagent to the hydroxyketone, then the hydride transfers to the carbonyl group via an intramolecular sense. Even in the case of 3-hydroxycyclohexanone, intramolecular hydride transfer from the complexed Al or B atom in the molecule occurred in preference to the intermolecular sense.…”

Section: Directive Effect Of the Hydroxy Group In The Cyclohexanone Smentioning

confidence: 99%

“…The high conversion ratio in the Na-[B(OAc) 3 H] reduction can be rationalized by assuming the intervention of the alkoxy species Na[B(OAc) 2 (OR)H]. 22 …”

Section: Directive Effect Of the Hydroxy Group In The Cyclohexanone Smentioning

confidence: 99%

“…Nitrogen Is Located at the c-Position in the Cyclohexanone Ring c-Azacyclohexanones such as l-aza-adamantan-4-one (20), l,2-dimethylpiperidin-4-one (21), and 2-oxoquinolizidine (22), in which the nitrogen atom is placed at the cposition to the carbonyl carbon in the cyclohexanone ring, were reduced with LiAlH 4 and NaBH 4 . The nitrogen lone pair of 20 is ®xed to the equatorial direction, whereas that of 21 and 22 is predominantly to the axial direction.…”

mentioning

confidence: 99%

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Role of the heteroatom on stereoselectivity in the complex metal hydride reduction of six‐membered cyclic ketones

Senda

2002

Chirality

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The role of the heteroatom on the stereochemistry and the relative rate for the complex metal hydride reduction of heteracyclohexanones and methoxy substituted cyclohexanones is explained by the difference in the nonbonding two electron stabilization between the incipient sigma* bond and the anti periplanar allylic sigma(i) bonds which were perturbed by the through space and/or through bond interaction with the remote heteroatom. A significant directive effect of the 2 axial hydroxyl group appears in the reduction of cyclohexanone with representative complex metal hydrides, while the 3 axial hydroxyl group exhibits a steric hindrance. The distance between the carbonyl carbon and the hydroxyl group which interacts with the hydride reagent is mainly responsible for such a difference. The key point of the extremely high directive effect appeared in the Na[B(OAc)(3)H] reduction for both 2 and 3 axial hydroxycyclohexanone is the formation of Na[B(OAc)(2)(OR)H], which is far more reactive than the parent hydride, by exchanging the acetate ion with the alkoxide.

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“…provided the 1,3-anti-diol 19 in 72% yield with moderate 1,3-stereoselectivity (84:16). 21 The diol 19 was then treated with 2,2-dimethoxypropane (10.0 equiv.) in the presence of a catalytic amount of PPTS to give the acetonide 20 in 65% yield.…”

mentioning

confidence: 99%