Deprotection of Arenesulfonamides with Samarium iodide

Vedejs, E.; Lin, Shuw-Guann

doi:10.1021/jo00086a005

Cited by 128 publications

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“…Photochemical conditions have been demonstrated to cleave nitrogensulfone bonds,37 however, irradiation of 16 with UV light (254 nm) in several solvents (entries 5–7) did not afford any useful amount of product. In the end, we turned to the SmI 2 ‐mediated radical reduction method 38. Gratifyingly, treatment of 16 with freshly prepared SmI 2 /THF solution selectively removed both the N ‐Ts and N ‐OMe groups without reduction of the pyrrolyl bromide, which ultimately provided (+)‐agelastatin A ( 1 ) in 88 % yield.…”

Section: Resultsmentioning

confidence: 99%

“…In the end, we turned to the SmI 2 -mediated radical reduction method. [38] Gratifyingly, treatment of 16 with freshly prepared SmI 2 /THF solution selectively removed both the N-Ts and N-OMe groups without reduction of the pyrrolyl bromide, which ultimately provided (+ )-agelastatin A (1) in 88 % yield. Synthetic (+ )agelastatin A displayed identical spectroscopic data ( 1 H NMR, 13 C NMR, IR, MS, and R f value) to those reported for the natural product.…”

Section: Introductionmentioning

confidence: 99%

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A Stereodivergent Strategy to Both Product Enantiomers from the Same Enantiomer of a Stereoinducing Catalyst: Agelastatin A

Trost

Dong

2009

Chemistry A European J

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In this article, we report a full account of our recent development of pyrroles and N-alkoxyamides as new classes of nucleophiles for palladium-catalyzed AAA reactions, along with application of these methodologies in the total synthesis of agelastatin A, a marine natural product with exceptional anti-cancer activity and other biological properties. Our method allows for access to either regioisomer of the pyrrolopiperazinones (6 and 19) with high efficiency and enantioselectivity. Note that isomer 19 was obtained via a cascade reaction through a double allylic alkylation pathway. From regioisomer 6, the total synthesis of (+)-agelastatin A was completed in a very short fashion (four steps from 6), during the course of which we developed a new copper catalyst for aziridination and an In (OTf) 3 -DMSO system to oxidatively open an Ntosyl aziridine. Starting with the other pyrrolopiperazinone 19, a five-step sequence has been developed to furnish a formal total synthesis of (−)-agelastatin A. A unique feature of our syntheses is the use of two rather different strategies for the total syntheses of both enantiomers of agelastatin A using the same enantiomer of a chiral palladium catalyst.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Stereodivergent Strategy to Both Product Enantiomers from the Same Enantiomer of a Stereoinducing Catalyst: Agelastatin A

Trost

Dong

2009

Chemistry A European J

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“…The solvent was evaporated, the residue recrystallized from water, and the product was further purified by ion-exchange resin (Dowex 50X8-400). Recrystallization from E1OH (80%) afforded pale, yellow needles ot 15 ( 3,4-Dicyano-trf,lV-diphenylbenzenesulfonamide (16) To a solution of 9 (1.80 g, 3 l-(3,4-Dicyanophenylsulfonyl)pyrrole (17) In a manner identical to that of 16 l-(3,4-Dicyanophenylsulfonyl)indole (18) As for 16 9,L0,16,11,23,24-Hexakis-(1 -heptyl)-2-(lpyrrolylsulfonyl)phthalocyanine (26) Excess 4,S-diheptylphthalonitrile (25) (29), prepared by our previously described method (32), (200 mg, 0.69 mmol) and 17 (20 mg. 0.078 mmol) were dissolved in DMAE (3 mL). As ammonia gas was brlbbled through, the reaction mixture was heated to I 00-1 lO'C (sand bath).…”

Section: -(34-dibromophenylsulphonyl)-35-dimethylpyrazole (R2)mentioning

confidence: 99%

“…Sulfona-mides are common compounds made from sulfonyl chlorides and amines, and sulfonamides are widely r"rsed as blocking groups of amines. Cleavage (16) of sulfonamides to recover the free amines is not a trivial operation, but a large number of sophisticated procedures (17) have been used to accomplish this task, often requiring harsh conditions such as the use of concentrated acid and high temperatures (18), or reducing agents (19). In most of these procedures little attention is paid to the sulfonic acid residue remaining after the cleavage, and indeed, the sulfonic acid group is often transformed in the process (17)(18)(19).…”

mentioning

confidence: 99%

Heterocyclic aromatic amide protecting groups for aryl and phthalocyaninesulfonic acids

Li¹,

Lier²,

Leznoff³

1999

Can. J. Chem.

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Pyroles, indole, imidazole, and a pyrazole were treated with 3,4-dibromobenzenesulfonyl chloride to form 3,4-dibromobenzenesulfonamides. The l-(3,4-dibromophenylsulfonyl)pyrrole and I -(3,4-dibromophenylsullonyl)indole were stable to CUCN iu DMF to produce l{3,4-dioyanophenylsulfonyl)pynole and l-(3.4-dicyanophenylsulfbnyl)indole, which upon treatment rvith ammonia in 2-N,,V-dimethylaminoethanol gave the protected phthalocyanine-2,9,16,23-tetrasulfonamides. Base cleavage of these sulfonamides yielded the free acids. A mixed conclensation of 4,5-diheptylphthalonitrile and 1-(3,4-dicyanophenylsulfonyl)pynole gave 9,10,16.17,23,24-hexakis(1-heptyl)-2-(lpyrrolylsulfonyl)phthalocyanine. Cleavage of the latter yielded the lithium salt of the monosulfonic acid.Ke"v words: sulfonic acid blocking groups, phthalocyanine sulfonic acids, l-(3,4-dicyanophenylsulfonyl)pynole, I -(3,4-dicyanophenyl sulfonyl)indole. 2). Although phthalocyanine -2,9,1 6,23 -tetr asulfonic acid is commercially available as a mixtufe of isomers, it has been shown that phthalocyanine-2-sulfonic acid ard plrthalocyanine-2,9-disulfonic acid are more effective for direct cell kill (3)(4)(5)(6)(7)(8)(9)

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“…We resolved to remove the tosyl group early in the synthesis. After smooth detosylation with samarium (II) diiodide14a,b the resulting ß-lactams were amenable to efficient completion of carbapenem synthesis (Scheme 2). …”

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confidence: 99%

A Catalytic Asymmetric Route to Carbapenems

Bodner¹,

Phelan²,

Townsend³

2009

Org. Lett.

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Efficient syntheses of N-acetyl thienamycin and epithienamycin A in readily deprotected form are reported where three contiguous stereocenters are established in a single catalytic asymmetric azetidinone-forming reaction. These examples are a template for synthesizing C5/C6 cis or trans carbapenems with independent control of the C8 stereocenter. A library of oxidatively and sterochemically defined azetidinone precursors to a variety of naturally-occurring carbapenems and potential biosynthetic intermediates has been prepared to facilitate studies of carbapenem antibiotic biosynthesis.

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Deprotection of Arenesulfonamides with Samarium iodide

Cited by 128 publications

References 0 publications

A Stereodivergent Strategy to Both Product Enantiomers from the Same Enantiomer of a Stereoinducing Catalyst: Agelastatin A

A Stereodivergent Strategy to Both Product Enantiomers from the Same Enantiomer of a Stereoinducing Catalyst: Agelastatin A

Heterocyclic aromatic amide protecting groups for aryl and phthalocyaninesulfonic acids

A Catalytic Asymmetric Route to Carbapenems

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