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Highly Diastereoselective Chelation-Controlled 1,3-anti-Allylation of (S)-3-(Methoxymethyl)hexanal Enabled by Hydrate of Scandium Triflate. Symmetry (Basel) 2021. [DOI: 10.3390/sym13030470] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
En route to the total synthesis of (+)-Neopeltolide, we explored Lewis acid-assisted diastereoselective allylation of MOM-protected 3-hydroxylhexanal with β-(2,2-diethoxyethyl)-substituted (allyl)tributylstannane. The hydrated form of scandium triflate was found to be essential for attaining high 1,3-anti-diastereoselectivity (d.r. 94:6), while the use of anhydrous catalyst resulted in a modest diastereocontrol (d.r. 76:24). The preferred 1,3-anti-selectivity in this transformation can be rationalized in the framework of the Reetz chelate model of asymmetric induction. The 1,3-anti-configuration of the product was confirmed by its conversion into the known C7-C16 building block of (+)-Neopeltolide. We also report an improved protocol for the synthesis of β-(2,2-diethoxyethyl)-substituted (allyl)tributylstannane, which can be utilized as a cost-efficient bipolar isoprenoid-type C5-building block in the synthesis of natural compounds.
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2
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Lee J, Kim J, Lee HY. Au(I)-Catalyzed Cyclization of Epoxyalkynes to Allylic Alcohol Containing Spiroketals and Application to the Total Synthesis of (-)-Alotaketal A. Org Lett 2020; 22:4073-4077. [PMID: 32391700 DOI: 10.1021/acs.orglett.0c01130] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A gold-catalyzed tandem spiroketalization of epoxyalkynes accompanied by epoxide rearrangement into the corresponding allylic alcohol was developed for the construction of functionalized spiroketals. This new synthetic methodology for unsaturated spiroketals warranted a facile total synthesis of alotaketal A from carvone via a corresponding epoxyalkyne precursor.
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Affiliation(s)
- Jaeyeon Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Dajeon 34141, Republic of Korea
| | - Jiheon Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Dajeon 34141, Republic of Korea
| | - Hee-Yoon Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Dajeon 34141, Republic of Korea
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3
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Luo G, Xiang M, Krische MJ. Successive Nucleophilic and Electrophilic Allylation for the Catalytic Enantioselective Synthesis of 2,4-Disubstituted Pyrrolidines. Org Lett 2019; 21:2493-2497. [PMID: 30816719 DOI: 10.1021/acs.orglett.9b00508] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Successive nucleophilic and electrophilic allylation mediated by the bis-Boc-carbonate derived from 2-methylene-1,3-propane diol enables formation of enantiomerically enriched 2,4-disubstituted pyrrolidines. An initial enantioselective iridium-catalyzed transfer hydrogenative carbonyl C-allylation is followed by Tsuji-Trost N-allylation using 2-nitrobenzenesulfonamide. Subsequent Mitsunobu cyclization provides the N-protected 2,4-disubstituted pyrrolidines.
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Affiliation(s)
- Guoshun Luo
- Department of Chemistry , University of Texas at Austin , Austin , Texas 78712 , United States
| | - Ming Xiang
- Department of Chemistry , University of Texas at Austin , Austin , Texas 78712 , United States
| | - Michael J Krische
- Department of Chemistry , University of Texas at Austin , Austin , Texas 78712 , United States
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4
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Abstract
In the presence of a chiral iridium complex, commercially available 3-chloro-2-chloromethyl-1-propene (1) was selectively activated for various reductive couplings. Depending on the reaction conditions it allows a selective mono- or bidirectional condensation with one or two external aldehydes with excellent enantiocontrol (>90% ee). This approach occurring simply under mild conditions and avoiding premetalated reagents constructs rapidly chiral homoallylic alcohols, key precursors of important molecular fragments such as furans, pyrans, ketodiols, or 1,3,5-polyols.
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Affiliation(s)
- Adrien Quintard
- Aix Marseille Univ , CNRS, Centrale Marseille, iSm2 , Marseille 13397 , France
| | - Jean Rodriguez
- Aix Marseille Univ , CNRS, Centrale Marseille, iSm2 , Marseille 13397 , France
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Masyuk VS, Mineeva IV. Synthesis of β-(2,2-diethoxyethyl)-substituted (allyl)tributylstannane and its application to asymmetric allylation. RUSSIAN JOURNAL OF ORGANIC CHEMISTRY 2016. [DOI: 10.1134/s1070428016020020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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6
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Cao B, Chen X, Yamaryo-Botte Y, Richardson MB, Martin KL, Khairallah GN, Rupasinghe TW, O’Flaherty RM, O’Hair RA, Ralton JE, Crellin PK, Coppel RL, McConville MJ, Williams SJ. Synthesis, Structural Elucidation, And Biochemical Analysis of Immunoactive Glucuronosyl Diacylglycerides of Mycobacteria and Corynebacteria. J Org Chem 2013; 78:2175-90. [DOI: 10.1021/jo302508e] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Paul K. Crellin
- Department of Microbiology, Monash University, Victoria 3800, Australia
| | - Ross L. Coppel
- Department of Microbiology, Monash University, Victoria 3800, Australia
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7
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Brooke DG, Shelley EJ, Roberts CG, Denny WA, Sutherland RL, Butt AJ. Synthesis and in vitro evaluation of analogues of avocado-produced toxin (+)-(R)-persin in human breast cancer cells. Bioorg Med Chem 2011; 19:7033-43. [PMID: 22044656 DOI: 10.1016/j.bmc.2011.10.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 09/28/2011] [Accepted: 10/05/2011] [Indexed: 10/16/2022]
Abstract
A structure-activity study of several new synthetic analogues of the avocado-produced toxin persin has been conducted, with compounds being evaluated for their cytostatic and pro-apoptotic effects in human breast cancer cells. A 4-pyridinyl derivative demonstrated activity comparable to that of the natural product, suggesting future directions for exploration of structure-activity relationships.
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Affiliation(s)
- Darby G Brooke
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
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8
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Trost BM, Frontier AJ, Thiel OR, Yang H, Dong G. Total synthesis of bryostatins: the development of methodology for the atom-economic and stereoselective synthesis of the ring C subunit. Chemistry 2011; 17:9762-76. [PMID: 21793057 PMCID: PMC3437499 DOI: 10.1002/chem.201002898] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 05/12/2011] [Indexed: 11/07/2022]
Abstract
Bryostatins, a family of structurally complicated macrolides, exhibit an exceptional range of biological activities. The limited availability and structural complexity of these molecules makes development of an efficient total synthesis particularly important. This article describes our initial efforts towards the total synthesis of bryostatins, in which chemoselective and atom-economical methods for the stereoselective assembly of the ring C subunit were developed. A Pd-catalyzed tandem alkyne-alkyne coupling/6-endo-dig cyclization sequence was explored and successfully pursued in the synthesis of a dihydropyran ring system. Elaboration of this methodology ultimately led to a concise synthesis of the ring C subunit of bryostatins.
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Affiliation(s)
- Barry M Trost
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA.
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9
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Lee HY, Murugan RN, Moon DK. Total Synthesis of (-)-13-Acetoxymodhephene and (+)-14-Acetoxymodhephene. European J Org Chem 2009. [DOI: 10.1002/ejoc.200900713] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Keck GE, Giles RL, Cee VJ, Wager CA, Yu T, Kraft MB. Total synthesis of epothilones B and D: stannane equivalents for beta-keto ester dianions. J Org Chem 2008; 73:9675-91. [PMID: 18991385 PMCID: PMC2736362 DOI: 10.1021/jo802215v] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Studies leading to a total synthesis of epothilones B and D are described. The overall synthetic plan was based on late-stage fragment assembly of two segments representing C(1)-C(9) and C(10)-C(21) of the structure. The C(1)-C(9) fragment was prepared by elaboration of commercially available (2R)-3-hydroxy-2-methylpropanoate at both ends of the three-carbon unit. Introduction of carbons 1-4 containing the gem-dimethyl unit was achieved in a convergent manner using a diastereoselective addition of a stannane equivalent of a beta-keto ester dianion. An enantioselective addition of such a stannane equivalent for a beta-keto ester dianion was also used to fashion one version of the C(10)-C(21) subunit; however, the fragment assembly (using bimolecular esterification followed by ring-closing metathesis) with this subunit failed. Therefore, fragment assembly was achieved using a Wittig reaction; this was followed by macrolactonization to close the macrocycle. The C(10)-C(21) subunit needed for this approach was prepared in an efficient manner using the Corey-Kim reaction as a key element. Other key reactions in the synthesis include a stereoselective SmI(2) reduction of a beta-hydroxy ketone and a critical opening of a valerolactone with aniline which required extensive investigation.
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Affiliation(s)
- Gary E Keck
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah, 84112, USA.
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Yoshida K, Takahashi H, Imamoto T. Synthesis of substituted benzenes and phenols by ring-closing olefin metathesis. Chemistry 2008; 14:8246-61. [PMID: 18663714 DOI: 10.1002/chem.200800484] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
New synthetic approaches to substituted aromatic compounds are reported. Ring-closing olefin metathesis (RCM)/dehydration and RCM/tautomerization are the key processes in the synthesis of substituted benzenes 3 and phenols 6, respectively. Readily accessible 1,5,7-trien-4-ols 7, which are the precursors of benzenes, were prepared from beta-halo-alpha,beta-unsaturated aldehydes 11 or beta-halo-alpha,beta-unsaturated esters 19 by utilizing reliable transformations in which cross-coupling with vinylic metal reagents 12 and allylation with allylic metal reagents 13 were employed as carbon-carbon bond forming reactions. RCM of 7, followed by dehydration, afforded a wide variety of substituted benzenes 3. In addition, RCM of 1,5,7-trien-4-ones 9, which were prepared by oxidation of 7, furnished various substituted phenols 6 by automatic tautomerization.
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Affiliation(s)
- Kazuhiro Yoshida
- Department of Chemistry, Graduate School of Science, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
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12
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Abstract
A vinylogous Mukaiyama aldol reaction, conducted using 10 mol % of a BITIP catalyst and B(OMe)3 as an additive, effects an enantioselective four-carbon chain extension to give versatile E-alpha,beta-unsaturated thiol esters.
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Affiliation(s)
- Lars V Heumann
- Department of Chemistry, University of Utah, 315 South 1400 East RM 2020, Salt Lake City, Utah 84112-0850, USA
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13
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Keck GE, Welch DS, Vivian PK. Synthetic studies toward the bryostatins: a substrate-controlled approach to the A-ring. Org Lett 2007; 8:3667-70. [PMID: 16898787 PMCID: PMC2516405 DOI: 10.1021/ol061173h] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] The synthesis of a C1-C13 A-ring subunit of bryostatin 1 is detailed. The key features of the approach include the convergent fragment assembly with a highly stereoselective construction of the C7-C8 bond indicated above.
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Affiliation(s)
- Gary E Keck
- Department of Chemistry, University of Utah, 315 South 1400 East RM 2020, Salt Lake City, Utah 84112-0850, USA.
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Heumann LV, Keck GE. A new construction of 2-alkoxypyrans by an acylation-reductive cyclization sequence. Org Lett 2007; 9:1951-4. [PMID: 17428064 PMCID: PMC2516373 DOI: 10.1021/ol070573h] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new convergent synthetic approach to a pyran motif common to many naturally occurring structures is described. In this approach, two fragments are joined by esterification, and a subsequent intramolecular reductive cyclization affords the 2-hydroxypyran.
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Affiliation(s)
- Lars V Heumann
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112-0850, USA
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15
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Keck GE, Welch DS, Poudel YB. Synthetic Studies Toward Bryostatin 1: Preparation of a C(1)-C(16) Fragment by Pyran Annulation. Tetrahedron Lett 2006; 47:8267-8270. [PMID: 17404602 PMCID: PMC1847416 DOI: 10.1016/j.tetlet.2006.09.094] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
An expeditious assembly of a C(1)-C(16) subunit of bryostatin 1 is described. A pyran annulation reaction was utilized to form the B-ring by reaction of a hydroxy-allylsilane with a fully elaborated A-ring subunit. This annulation process proceeded with complete diastereoselectivity and in excellent isolated yield despite the presence of potentially sensitive functionality in the A-ring segment.
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Affiliation(s)
- Gary E Keck
- Department of Chemistry, University of Utah, 315 South 1400 East, RM 2020, Salt Lake City, Utah 84112-0850, USA
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16
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Keck GE, Truong AP. Synthetic studies on the bryostatins: preparation of a truncated BC-ring intermediate by pyran annulation. Org Lett 2006; 7:2149-52. [PMID: 15901156 PMCID: PMC1480406 DOI: 10.1021/ol050511w] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[reaction: see text]. A synthesis of a potential BC-ring subunit (C9-C27) for bryostatin 1, a remarkably potent anticancer agent, has been developed in 16 steps and 18% overall yield. The key features of this route include a BITIP-catalyzed asymmetric allylation reaction, chelation-controlled allylations, a hydroformylation reaction, and a pyran annulation reaction.
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Affiliation(s)
- Gary E Keck
- Department of Chemistry, University of Utah, 315 South 1400 East RM 2020, Salt Lake City, Utah 84112-0850, USA
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