Asymmetric pinacol-type rearrangement of α-hydroxy methanesulfonates promoted by triethylaluminum — preparation of optically pure α-aryl and α-vinyl ketones —

Suzuki, Keisuke; Katayama, E.; Tsuchihashi, Gen-ichi

doi:10.1016/s0040-4039(01)99831-4

Cited by 51 publications

(22 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The experimentally observed stereospecific 1,2-shift (Scheme 5; R = vinyl) could be explained by the excellent migratory aptitude of a vinyl group, [14] which suppresses the intervention of the stereomutating process. Two cationic species, A and B, can potentially be generated from the cis diol.…”

mentioning

confidence: 99%

Isoxazole‐Directed Pinacol Rearrangement: Stereocontrolled Approach to Angular Stereogenic Centers

et al. 2007

Self Cite

View full text Add to dashboard Cite

In our synthetic studies towards some polyketide-derived natural products, including seragakinone A (1) [1] and the antibiotic BE-43472A (2), [2] we required a general and effective method for establishing quaternary stereogenic centers at the angular position in these polycyclic compounds (Scheme 1). With the recognition that conventional strategies for the stereocontrolled construction of quaternary carbon centers, for example, enolate alkylation and nucleophilic displacement reactions, [3] would not provide a general solution to this problem, we envisaged that an indirect but efficient route to the angularly substituted ketone II would be available by the pinacol rearrangement of the tricyclic diol I (Scheme 2). [4] For such a scenario to be feasible, however, two critical requirements must be fulfilled: 1) The diol I needs to be readily available in a stereodefined form, and 2) the 1,2-shift must occur in a regioselective and stereospecific manner. The latter criterion is challenging, because the two hydroxy groups in I are both tertiary and therefore equally susceptible to acidactivated departure. Even if selective activation of the angular hydroxy group is possible, the relative migratory aptitudes of the pendant groups may induce further complications.We now report the successful implementation of this strategy in the form of an isoxazole-directed pinacol rearrangement for the stereoselective introduction of angular substituents in polycyclic systems. Scheme 3 illustrates the two-step process, which has two crucial attributes. First, the cis diol 4 is readily accessible in stereocontrolled manner by the addition of a nucleophile (R À ) to the readily prepared chiral, nonracemic ketol 3. [5,6] Second, the pinacol rearrangement, 4!5, proceeds in a regioselective and stereospecific manner as a result of the excellent, and underappreciated, acation-stabilizing ability of an isoxazole.Pleasingly, the addition of carbon nucleophiles to ketol 3 occurred in a highly cis-selective manner under various conditions. For example, the slow addition of a solution in THF of ketol (R)-3 (98 % ee) to a solution of vinyllithium [7] in Et 2 O at À78 8C gave the cis diol 4 a after 5 min as a single product in 99 % yield (Scheme 4). Enantiomeric purity was preserved during this process, as evidenced by HPLC analysis on a chiral stationary phase; [8] diol 4 a was obtained with 98 % ee. Scheme 1. Polyketide-derived polycyclic natural products with angular substitution.Scheme 2. Pinacol-rearrangement approach for installing angular substituents.Scheme 3. Two-step installation of angular substituents. Bn = benzyl.Scheme 4. Installation of an angular vinyl group.

show abstract

mentioning

confidence: 99%

Isoxazole‐Directed Pinacol Rearrangement: Stereocontrolled Approach to Angular Stereogenic Centers

et al. 2007

Self Cite

View full text Add to dashboard Cite

show abstract

“…The experimental procedures were the same as described for the preparation of 4a. 7 ) The yield of 9b was 94%.…”

Section: Preparation Of (S)-2-phenyl-3-tridecanone (9b)mentioning

confidence: 96%

Stereoselective Oxidation ofβ-Methyl-sec-alcohols andα-Methylketones byCorynebacterium equiIFO 3730

Ohta

Iwabuchi

Tsuchihashi

1986

Agricultural and Biological Chemistry

Self Cite

View full text Add to dashboard Cite

The enzyme system of Corynebacterium equi IFO 3730 catalyzed' the diastereo-selective oxidation of f3-methyl-sec-alcohols. For example, only the erythro isomer of 5-methyl-6-tetradecanol was oxidized to the corresponding ketone, the threo-alcohol remaining. Moreover, the resulting ketone was metabolized enantioselectively by the same microbe. 'Thus, it was possible to obtain optically active a-methylketones. This biochemical kinetic resolution method was applied for some 2-phenyl-3-alkanones, the expected chiral ketones of moderate to highoptical purities being obtained. The degradation pathway was deduced to involve Baeyer-Villiger type oxidation, on the basis of the isolation of small amouts of a-phenylethyl alcohol and acetophenone.

show abstract

“…This type of pinacol rearrangement was rst reported on different system by Tsuchihashi. 90 The next macrocyclic construction, culminating in the molecule Haouamine, gave us pause as we could not quite decide where in this account to insert it. On the one hand, the presence of the biaryl moiety in Haouamine suggested that Baran's synthesis could have been discussed aer Nicolaou's Diazonamide synthesis in which the installation of the biaryl was achieved by a single electron oxidation/reduction.…”

Section: Distinctive Macrocyclic Domains and The Most Appropriate Metmentioning

confidence: 99%

“…On the other hand, Baran's solution to the problem of the strained biaryl moiety within Haouamine involved such an ingenious use of Diels Alder chemistry, that it seemed appropriate to discuss this innovation aer Schreiber's 91 exhilarating Diels Alder accomplishment. 90 Haouamine A is a structurally unique alkaloid. The most outstanding feature of this alkaloid is the 11 membered ring that links an indeno-tetrahydropyridine and a strained biaryl moiety (an aza-paracyclophane) in which one of the benzene rings of the biaryl system is in the boat conformation.…”

Section: Distinctive Macrocyclic Domains and The Most Appropriate Metmentioning

confidence: 99%

Treasures old and new: what we can learn regarding the macrocyclic problem from past and present efforts in natural product total synthesis

et al. 2020

View full text Add to dashboard Cite

show abstract

Asymmetric pinacol-type rearrangement of α-hydroxy methanesulfonates promoted by triethylaluminum — preparation of optically pure α-aryl and α-vinyl ketones —

Cited by 51 publications

References 11 publications

Isoxazole‐Directed Pinacol Rearrangement: Stereocontrolled Approach to Angular Stereogenic Centers

Isoxazole‐Directed Pinacol Rearrangement: Stereocontrolled Approach to Angular Stereogenic Centers

Stereoselective Oxidation ofβ-Methyl-sec-alcohols andα-Methylketones byCorynebacterium equiIFO 3730

Treasures old and new: what we can learn regarding the macrocyclic problem from past and present efforts in natural product total synthesis

Contact Info

Product

Resources

About