Synthesis of 11-oxatricyclo[5.3.1.02,6]undecane derivatives via organometallic cyclizations

Belle, B. E. La; Knudsen, Mark J.; Olmstead, Marilyn M.; Hope, H.; Yanuck, Michael D.; Schore, Neil E.

doi:10.1021/jo00225a046

Cited by 63 publications

(21 citation statements)

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“…Since the early reports of Pauson and co‐workers,23a–c in which they showed norbornenes to be the most successful alkene partners, there have been many examples of their use in the presence of different metals and under different reaction conditions,15b–f, 30c, f, 32b, g, 40, 68a in the asymmetric version of the reaction,28e,h, 32d, i, 41 and in heterogeneous systems 30g–i. 42 Related systems such as 8‐oxabicyclo[3.2.1]octenes28b, 43 and heteroatom‐containing bicyclo[2.2.1]heptenes,28f, 40b, p, 42a, 43c, 44, 45 reveal similar or slightly lower levels of reactivity. As the literature contains so many examples, we have selected just two reports, one for its current importance in the field (Scheme ) and one for its exoticism (Scheme ).…”

Section: Reactive Alkene Partners: the Lumo Energymentioning

confidence: 99%

The Intermolecular Pauson–Khand Reaction

2005

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Five membered carbocycles are important building blocks for many biologically active molecules. Moreover, substituted cyclopentenones (e.g. cyclopentenone prostaglandins) exhibit characteristic biological activity. The efficiency and atom economy of the Pauson-Khand reaction render this process potentially one of the most attractive methods for the synthesis of such compounds. Although it was discovered in its intermolecular form, the scope of the intermolecular Pauson-Khand reaction has always been limited by the poor reactivity and selectivity of the alkene component. The past decade, especially the last three years, has seen concerted efforts to broaden the scope of this reaction. In this overview, we provide a comprehensive and critical coverage of the intermolecular Pauson-Khand reaction based on the reactivity characteristics of different classes of alkenes and a rationalization of successes and misfortunes in this area.

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Section: Reactive Alkene Partners: the Lumo Energymentioning

confidence: 99%

The Intermolecular Pauson–Khand Reaction

2005

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“…It is well-known from the work of Pauson that the reaction of norbornene is completely exo-face selective. [15,16] Scheme 2 Modest regioselectivity in favour of regioisomer 6 was observed by Schore for 1-methyl-5-norbornen-2-one.…”

Section: Methodsmentioning

confidence: 95%

“…In order to rationalize the regioselectivities observed for bicyclic alkenes 5, Schore has proposed a mechanism [16] in which exo attack of the alkene at the basal anti coordination site of the cobalt cluster 1 results in the formation of four different insertion products. According to his rationale, a pseudo-1,3-diaxial interaction between a carbon monoxide ligand and the angular methyl group is the most important factor governing the regioselectivity.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of the Regioselectivity in Pauson-Khand Reactions of Substituted Norbornenes and Diazabicyclo[2.2.1]heptanes with Terminal Alkynes

Derdau

Laschat²,

Jones

2000

Eur. J. Org. Chem.

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1‐Methyl‐norbornene ester 9 and 1‐methyl‐2,3‐diazabicyclo[2.2.1]heptene ester 10 were employed in intermolecular Pauson‐Khand reactions with various terminal alkynes 11a‐f to give the dimethyl 1‐methyltricyclo[5.2.1.05,9]dec‐7‐en‐6‐one 2,3‐dicarboxylates 12 and 13, and diethyl 2,3‐diaza‐1‐methyltricyclo[5.2.1.05,9]dec‐7‐en‐6‐one 2,3‐dicarboxylates 14 and 15, respectively. Whereas the co‐cyclization of norbornene 9 with alkynes 11 bearing small substituents R resulted in the preferred formation of 12 (12:13 ≤ 85:15), regioisomer 13 was obtained as the major product when sterically bulky alkynes were employed (12:13 ≥ 6:94). For 2‐methyl‐3‐butyn‐2‐ol 11e a strong temperature dependency of the regioselectivity was found. The ratio of regioisomers (12e:13e) changed from 95:5 at ‐25 °C to 12:88 at 120 °C in toluene. In contrast, reactions with 2,3‐diazanorbornene 10 showed only moderate regioselectivities in favour of 14 (14:15 ≤ 69:31), regardless of the temperature and the size of R. The observed regioselectivities support a mechanism for the Pauson‐Khand reaction in which the apical rather than the basal anti oriented carbon monoxide ligand of cobalt alkyne complex 1 is replaced by the alkene.

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“…The first includes the step of acetylene complex preformation, 154a, 155 and the second is a one-pot procedure, which proposes the simultaneous mixing of all the components in the reaction vessel. 156 Dicobalt octacarbonyl can be replaced by the other catalysts. Among them are tetracobalt dodecacarbonyl, 157 cobalt acetyl acetonate -sodium borohydride system, 158 and mixtures of Co 2 (CO) 8 with nitrous oxide.…”

Section: (2+2+1) Cycloadditionmentioning

confidence: 99%