Synthesis of (−)-Hamigeran B

Taber, Douglass F.; Tian, Weiwei

doi:10.1021/jo8010683

Cited by 63 publications

(40 citation statements)

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“…This phenomenon was exploited by Taber in his synthesis of (−)-hamigeran B (Scheme 13). 27 Reaction of α-aryl-α-diazoketone 48 in the presence of Rh 2 ( S -PTTL) 4 led to the C—H insertion product 49 in 83% yield, with full stereocontrol of the quaternary center. The reaction, however, produced a mixture of diastereomers alpha to the cabonyl.…”

Section: Intramolecular C—h Insertionmentioning

confidence: 99%

Application of donor/acceptor-carbenoids to the synthesis of natural products

2009

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The metal catalyzed reactions of diazo compounds have been broadly used in organic synthesis. The resulting metal-carbenoid intermediates are capable of undergoing a range of unconventional reactions, and due to their high energy, they are ideal for initiating a cascade sequence leading to rapid the rapid generation of structural complexity. This tutorial review will be give an overview of the most versatile reactions of donor/acceptor carbenoids, an exciting class of intermediates capable of highly selective reactions. This will include cyclopropanation, [4 + 3] cycloaddition, and C–H functionalization methodologies. The application of this chemistry to the synthesis of a range of natural products will be described.

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Section: Intramolecular C—h Insertionmentioning

confidence: 99%

Application of donor/acceptor-carbenoids to the synthesis of natural products

2009

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“…= 5:1) with as even-membered Bring. [2a] Naturally occurring 7 and N-Q (8)(9)(10)(11), as well as their 18epi isomers contain the basic skeleton (A-B-C ring) of 6 with an unusual benzoxazine Dring. [22] Va rious brominating reagents were tested for their ability to achieve regioselective o-bromination of the phenol 43,i ncluding NBS/iPr 2 NH, tetrabutylammonium tribromide,a nd pyrrolidone hydrotribromide.Pyridinium tribromide (py·HBr 3 )was found to work best, thus providing the monobrominated product in excellent yield.…”

Section: Methodsmentioning

confidence: 99%

“…In summary,wehave accomplished the first total synthesis of hamigerans L( 4), G( 6), D ( 7), and N-Q (8)(9)(10)(11). A convergent synthetic strategy was developed based on the versatile common intermediate 28.O ur results suggest that benzoxazine-containing 7 and 8-11 may derive from naturally occurring amino acids and 6.W ebelieve that this biomimetic approach should enable the synthesis of av ariety of hamigerans and their derivatives,t hus facilitating biological studies of these promising natural products.W eare currently studying the total synthesis of the gukulenins.…”

Section: Methodsmentioning

confidence: 99%

“…[4] Many synthetic studies have been reported, including those by the groups of Nicolaou, [5] Clive, [6] Tr ost, [7] Taber, [8] Stoltz, [9] Lau, [10] Jiang, [11] Miesch, [12] Xie and Zhou, [13] and others. [4] Many synthetic studies have been reported, including those by the groups of Nicolaou, [5] Clive, [6] Tr ost, [7] Taber, [8] Stoltz, [9] Lau, [10] Jiang, [11] Miesch, [12] Xie and Zhou, [13] and others.…”

mentioning

confidence: 99%

“…[4] Many synthetic studies have been reported, including those by the groups of Nicolaou, [5] Clive, [6] Tr ost, [7] Taber, [8] Stoltz, [9] Lau, [10] Jiang, [11] Miesch, [12] Xie and Zhou, [13] and others. Herein we report the first total synthesis of hamigeran G( 6)a nd its biomimetic transformation into hamigerans L(4), D (7), and N-Q (8)(9)(10)(11). Herein we report the first total synthesis of hamigeran G( 6)a nd its biomimetic transformation into hamigerans L(4), D (7), and N-Q (8)(9)(10)(11).…”

mentioning

confidence: 99%

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Total Synthesis of the Hamigerans

Xue

Wang

et al. 2016

Angewandte Chemie

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The first total synthesis of hamigerans D, G, L, and N-Q has been accomplished. Aconvergent approachwas used to build the basic tricarbocyclic ring system bearing a5 -6-6 structure.Asequence of oxidative cleavage,homologation, and ring regeneration provided access to the 5-7-6 skeleton of hamigeran G. Based on the biogenetic hypothesis,elegant and highly efficient biomimetic transformations of hamigeran G into hamigerans D, N-Q, and Lw ere achieved. Scheme 4. Total synthesis of 6.X-ray structures are shown. Thermal ellipsoidss hown at 50 %probability. [24] DMP = Dess-Martin periodinane, NMO = 4-methyl-morpholin-4-oxide, PTSA = p-toluenesulfonic acid, Py = pyridine.Scheme 5. Biomimetic transformation of 6 into 8 and its 18-epi isomer.

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Catalytic, Asymmetric, Intramolecular Carbon–Hydrogen Insertion

2012

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The insertion of a chiral‐ligated metal carbene into an aliphatic C‐H bond to construct a carbon‐carbon bond imparts asymmetry into the resultant molecule to form enantiomerically enriched lactones, lactams, and cycloalkane derivatives and returns the chiral‐ligated metal to its catalytically active state. Insertion is favored by electron‐donating groups adjacent to the C‐H bond that undergoes insertion, and is disfavored by electron‐withdrawing groups. Chiral dirhodium(II) carboxamidates have proven to have the greatest breadth of high selectivities, but other classes of catalysts are selective in specific cases. Although there are examples of iodonium ylides as reactants, diazo compounds are the reactants of choice for these reactions. Diazocarbonyl compounds, especially diazoacetates and diazoacetamides, have reactivities and selectivities that are most suitable for high product yields and high stereoselectivities. This reaction is optimally designed for the formation of five‐membered ring compounds using diazoacetates and diazoacetamides and of four‐membered ring products with constrained diazoacetamides. Access to lignan lactones, baclofen, deoxyxylolactone, and rolipram, among others, exemplify the efficiencies of this methodology relative to other synthetic approaches.

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Synthesis of (−)-Hamigeran B

Abstract: The synthesis of (-)-hamigeran B has been achieved, based on a new approach to cyclopentane construction, the rhodium-mediated intramolecular C-H insertion of α-aryl-α-diazo ketones. The endo isopropyl group was installed by selective hydrogenation of a cyclopropylidene substituent.

Cited by 63 publications

References 33 publications

Application of donor/acceptor-carbenoids to the synthesis of natural products

Application of donor/acceptor-carbenoids to the synthesis of natural products

Total Synthesis of the Hamigerans

Catalytic, Asymmetric, Intramolecular Carbon–Hydrogen Insertion

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