Keto boronate reduction: 1,7-asymmetric induction

Molander, Gary A.; Bobbitt, Kevin L.

doi:10.1021/ja00069a067

Cited by 51 publications

(7 citation statements)

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“…3 As one example out of the many accomplishments can be mentioned the work of Molander et al, who showed that the carbonyl group in ketoboronates 1 could be reduced with excellent diastereoselectivity, despite a distance of six bonds between existing and the newly formed stereocenters (Scheme 1, eqn (I)). 4 Another classic example involves the SAMP/RAMP hydrazine derivative 3, which upon lithiation underwent conjugate addition to methyl crotonate 4 (eqn (II)). 5 Remarkably, the stereochemical information is perfectly relayed over ve bonds, furnishing the adduct 5 with >96% de.…”

Section: Introductionmentioning

confidence: 99%

Aminocatalytic remote functionalization strategies

2013

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The recent development in organocatalytic remote functionalization strategies will be outlined. The application of aminocatalysis for the activation of unsaturated carbonyl compounds has led to tremendous development of new interesting methodologies providing chiral frameworks relevant for life-science. Spectacular examples of chirality relayed to a new stereogenic centers located at five (for g-functionalizations) to seven (for 3-functionalizations) bonds away from the stereodifferentiating element of the aminocatalyst will be demonstrated. The site-specificity of these strategies is particularly intriguing and it will be outlined how such regioselectivity is controlled by the substitution patterns of the starting carbonyl compounds. Furthermore, in most of the cases these aminocatalytic remote functionalizations proceed with high enantio-and diastereoselectivities. The applied aminocatalysts govern the stereochemical outcome of the reactions by either the steric shielding or the hydrogen-bond directing principle. One very important aspect of these two stereodifferentiating approaches is their complementarity, opening access to a variety of enantioenriched acyclic, hetero-and carbocyclic compounds. The application of remote functionalization approaches as the key steps in the total synthesis of several natural products or drugs will also be presented.

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Section: Introductionmentioning

confidence: 99%

Aminocatalytic remote functionalization strategies

2013

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“…A plausible explanation for the reduced cyclization rate of these boroSar inhibitors is the formation of an intramolecular five-membered (:OC−N−C−B) ring structure in which the carbonyl oxygen atom coordinates to the boron, effectively stabilizing the active trans conformer of the dipeptide. Such intramolecular five-membered-ring motifs with a B−O dative bond have been observed in esters derived from boronic acids, − and postulated as intermediates in the stereoselective reduction of neighboring carbonyl groups. − However, relatively little is known about the factors associated with the formation of these intramolecular (:OC−N−C−B) rings, or their influence on the therapeutic efficacy of potential drugs. It should be mentioned that the presence of intramolecular B−N dative bonds has been correlated to some unexpected physiological behavior. − …”

Section: Introductionmentioning

confidence: 99%

“…Such intramolecular fivemembered-ring motifs with a B-O dative bond have been observed in esters derived from boronic acids, 25-27 and postulated as intermediates in the stereoselective reduction of neighboring carbonyl groups. [28][29][30] However, relatively little is known about the factors associated with the formation of these intramolecular (:OdC-N-C-B) rings, or their influence on the therapeutic efficacy of potential drugs. It should be mentioned that the presence of intramolecular B-N dative bonds has been correlated to some unexpected physiological behavior.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Structural Investigation of Internally Coordinated α-Amidoboronic Acids

Lai

Liu

et al. 2005

J. Org. Chem.

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[structure: see text] Six new N-acyl-boroGly derivatives, along with their N-acyl-boroSar analogues, have been synthesized by modification of conventional procedures. Structural characterization of these alpha-amidoboronic acids was accomplished by extensive use of 11B and 1H NMR spectroscopy. These compounds were prepared to determine the extent of intramolecular B-O dative bond formation within the context of a five-membered (:O=C-N-C-B) ring motif. It is shown that the formation of such dative bonds depends on the nature of the substituents at both the acyl carbon and the nitrogen atoms. Computational evidence from second-order Møller-Plesset perturbation theory is provided in support of these findings.

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“…Chan and co-workers were the first to report TiCl 4 -mediated formal [3 þ 3] cyclocondensation reactions with 1,3-bis[(trimethylsilyl)oxy]buta-1,3-dienes, which can be regarded as masked 1,3-dicarbonyl dianions [8] [9]. These dienes can be prepared in two steps from the corresponding 1,3-dicarbonyl compounds [10], and they represent important synthetic building blocks [11]. Herein, we report a new and convenient synthesis of functionalized octahydro-indeno-phenanthrenes by formal [3 þ 3] cyclocondensations of 1,3-bis[(trimethylsilyl)oxy]buta-1,3-dienes with a silyl enol ether derived from 6.…”

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confidence: 99%