Synthesis of Amphidinolide T1 via Catalytic, Stereoselective Macrocyclization

Colby, Elizabeth A.; O’Brien, Karen C.; Jamison, Timothy F.

doi:10.1021/ja039716v

Cited by 98 publications

(38 citation statements)

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“…(4.6)) from those of the original Ni(0)/PBu 3 The two nickel-catalyzed reductive coupling reactions, alkyne-epoxide (Scheme 4.39) and alkyne-aldehyde (Scheme 4.37(a)), developed by Jamison, have been successfully applied to an enantioselective total synthesis of amphidinolide T1 (Scheme 4.40) [90].…”

Section: Addendamentioning

confidence: 99%

Reaction of Alkynes

Ikeda

2005

Modern Organonickel Chemistry

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Since the earliest investigations represented by cycloaddition [1] and carboxylation [2], the nickel-catalyzed reactions of alkynes have been extensively studied by many research groups. This chapter highlights recent developments in the nickelcatalyzed reactions of alkynes. Recent advancements in cycloaddition and the carboxylation of alkynes are described in Chapters 6 and 7, respectively.The most extensively studied reaction is the addition reaction of an AaB species (e.g., HaH, H-metals, metals-metals, CaH, and C-metals, where metals ¼ Si, Sn, B, etc.) to alkynes (Scheme 4.1). Generally, the addition of an AaB species to alkynes starts with oxidative addition of the AaB species to a nickel(0) complex to generate an AaNiaB species (see Section 1.7.1). The insertion of an alkyne into either the AaNi or the BaNi bond gives the alkenylnickel intermediate(s), which undergo reductive elimination to produce the alkenes functionalized with an A and B functionalities at the 1,2-positions (see Section 1.7.4). The A and B groups are usually introduced on the same face of alkynes, and cis-alkenes with respect to A and B are produced. When an AaB is CaX (X ¼ halogens, O, N), the alkenylnickel X intermediates are capable of undergoing, instead of reductive elimination, Modern Organonickel Chemistry. Edited by Y. Tamaru

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Section: Addendamentioning

confidence: 99%

Reaction of Alkynes

Ikeda

2005

Modern Organonickel Chemistry

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“…Subsequent Sonogashira coupling with iodobenzene furnished target alcohol 23 in near quantitative yield, constituting a vast improvement over the onestep propargylation with allenylsilane 22 that we had reported previously. 7 With the installation of the substituted tetrahydrofuran ring achieved by the allenylstannane addition, introduction of the remaining stereogenic center of carboxylic acid 10 was the next challenge to address. This was accomplished using an auxiliary-controlled, diastereoselective alkylation reaction.…”

Section: Synthesis Of Amphidinolide T1: Assembly Of C1-c12 Fragmentmentioning

confidence: 99%

“…T1 or otherwise), this approach features the installation of a stereogenic center (>10:1 diastereoselectivity) during the macrocyclization event. Herein, we disclose the implementation of this strategy in a full account of our synthesis of amphidinolide T1 7 and a previously unreported synthesis of T4.…”

Section: Introductionmentioning

confidence: 99%

Total Syntheses of Amphidinolides T1 and T4 via Catalytic Stereoselective, Reductive Macrocyclizations.

2005

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Described in this work are total syntheses of amphidinolides T1 and T4 using two nickel-catalyzed reductive coupling reactions of alkynes, with an epoxide in one case (intermolecular) and with an aldehyde in another (intramolecular). The latter was used to effect a macrocyclization, form a C-C bond and install a stereogenic center with >10:1 selectivity in both natural product syntheses. Alternative approaches in which intermolecular alkyne-aldehyde reductive coupling reactions would serve to join key fragments were investigated and are also discussed; it was found that macrocyclization (i.e. intramolecular alkyne-aldehyde coupling) was superior in several respects (diastereoselectivity, yield, and length of syntheses). Alkyne-epoxide reductive couplings were instrumental in the construction of key fragments corresponding to approximately half of the molecule of both natural products. In one case (T4 series), the alkyne-epoxide coupling exhibited very high site selectivity in a coupling of a diyne. A model for the stereoselectivity observed in the macrocyclizations is also proposed.

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“…[2] The utility of this concept has been demonstrated well in organic synthesis. [3] A similar reaction sequence employing arynes as a p component would be highly interesting and useful, considering that arynes are generally very reactive and generated in situ and that the reaction would lead to the formation of two different CÀC bonds in ortho positions of a benzene ring.…”

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confidence: 99%

“…Benzeneboronic acid (3 f) provided product 4 t in 60 % yield (Table 2, entry 12). In the case of boronic acids 3 e and 3 f, phosphine ligand P(p-C 6 H 4 F) 3 was employed, as the reaction did not proceed when PPh 3 was used as the ligand. A plausible mechanistic rationale for the present catalytic reaction is shown in Scheme 1.…”

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confidence: 99%