Synthesis of multi-substituted furan rings: the role of silicon

Keay, Brian A.

doi:10.1039/a809439j

Cited by 196 publications

(48 citation statements)

References 31 publications

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“…This unique 1,2‐Si migration is particularly attractive as it allows the synthesis of hitherto inaccessible unsymmetrical 2,3‐disubstituted C‐4 silylated chiral furans 16a. Further work is in progress to increase the yield of the desired product.…”

Section: Resultsmentioning

confidence: 99%

Gold(III) Chloride Catalyzed Synthesis of Chiral Substituted 3‐Formyl Furans from Carbohydrates: Application in the Synthesis of 1,5‐Dicarbonyl Derivatives and Furo[3,2‐c]pyridine

Mal

Sharma

Das

2014

Chemistry A European J

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This report describes a gold(III)-catalyzed efficient general route to densely substituted chiral 3-formyl furans under extremely mild conditions from suitably protected 5-(1-alkynyl)-2,3-dihydropyran-4-one using H2 O as a nucleophile. The reaction proceeds through the initial formation of an activated alkyne-gold(III) complex intermediate, followed by either a domino nucleophilic attack/anti-endo-dig cyclization, or the formation of a cyclic oxonium ion with subsequent attack by H2 O. To confirm the proposed mechanistic pathway, we employed MeOH as a nucleophile instead of H2 O to result in a substituted furo[3,2-c]pyran derivative, as anticipated. The similar furo[3,2-c]pyran skeleton with a hybrid carbohydrate-furan derivative has also been achieved through pyridinium dichromate (PDC) oxidation of a substituted chiral 3-formyl furan. The corresponding protected 5-(1-alkynyl)-2,3-dihydropyran-4-one can be synthesized from the monosaccharides (both hexoses and pentose) following oxidation, iodination, and Sonogashira coupling sequences. Furthermore, to demonstrate the potentiality of chiral 3-formyl furan derivatives, a TiBr4 -catalyzed reaction of these derivatives has been shown to offer efficient access to 1,5-dicarbonyl compounds, which on treatment with NH4 OAc in slightly acidic conditions afforded substituted furo[3,2-c]pyridine.

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Section: Resultsmentioning

confidence: 99%

Gold(III) Chloride Catalyzed Synthesis of Chiral Substituted 3‐Formyl Furans from Carbohydrates: Application in the Synthesis of 1,5‐Dicarbonyl Derivatives and Furo[3,2‐c]pyridine

Mal

Sharma

Das

2014

Chemistry A European J

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“…26 Consequently, numerous reviews covering a large number of the existing synthetic methods toward furans via a modification of preexisting heterocyclic core 2g,27 and assembly of the ring from acyclic precursors 21b,28 have appeared. In this chapter, synthesis of furans via transition metal-catalyzed processes is discussed.…”

Section: Synthesis Of Furansmentioning

confidence: 99%

Transition Metal-Mediated Synthesis of Monocyclic Aromatic Heterocycles

et al. 2013

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“…In particular, development of catalytic approaches for furan syntheses under mild reaction conditions from simple starting materials still remains an active task for the synthetic community. Consequently, numerous attempts at systematization of the vast array of existing synthetic methods toward the preparation of furans via modification of the preexisting heterocyclic core [6,80,81] and assembly of the ring from acyclic precursors [82,83] have been made. Among the two, the latter has a greater potential for rapid construction of diversely substituted heterocycles.…”

Section: Furansmentioning

confidence: 99%

Transition Metal‐Catalyzed Synthesis of Monocyclic Five‐Membered Aromatic Heterocycles

Dudnik

Gevorgyan

2010

Catalyzed Carbon‐Heteroatom Bond Formation

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Aromatic heterocycles, particularly furans and pyrroles, are structural motifs found in a vast number of biologically active natural and artificial compounds [1][2][3]. Other examples of practical applications of furans and pyrroles include dyes, polymers, and electronic materials [4]. Moreover, these heterocycles are employed as important intermediates in organic synthesis [5][6][7][8][9]. The successful application of furans and pyrroles in these and many other ways and their significance in applied and fundamental areas have placed them at the forefront of contemporary organic chemistry. A variety of methodologies and different protocols for their synthesis have been reported [1-3, 10-23] and become well established throughout decades. Among the variety of novel approaches for the synthesis of furans and pyrroles, transition metal-catalyzed transformations are arguably the most attractive methodologies . Several excellent reviews on the transition metal-catalyzed synthesis of monocyclic five-membered heterocycles have been published in the literature. Many of them were categorized by either the metal or the type of transformation. This chapter covers transition metal-catalyzed syntheses of furans and pyrroles. The main organization of this chapter is based on a heterocycle, wherein syntheses of a particular core are structured by the type of transformation and substrates engaged. Herein, we have tried to discuss equally the synthetic applicability of a method and mechanistic aspects and concepts implicated in the described transformations. A discussion of the mechanisms is given when needed to provide an idea about possible reaction pathways and the nature of the elementary processes involved in the catalytic transformation. It should be noted that the most essential and general catalytic reactions, as well as recent and conceptionally interesting transformations, are discussed in more detail in this chapter. Syntheses of furans and pyrroles via functionalization of the preexisting heterocyclic cores [37,[52][53][54][55][56][57][58][59][60] are not covered and, therefore, only reactions in which assembly of a heterocyclic ring occurs are described. In addition, the Pd-catalyzed synthesis of heterocycles is not covered herein, as this topic is covered in Chapter 6.

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Synthesis of multi-substituted furan rings: the role of silicon

Cited by 196 publications

References 31 publications

Gold(III) Chloride Catalyzed Synthesis of Chiral Substituted 3‐Formyl Furans from Carbohydrates: Application in the Synthesis of 1,5‐Dicarbonyl Derivatives and Furo[3,2‐c]pyridine

Gold(III) Chloride Catalyzed Synthesis of Chiral Substituted 3‐Formyl Furans from Carbohydrates: Application in the Synthesis of 1,5‐Dicarbonyl Derivatives and Furo[3,2‐c]pyridine

Transition Metal-Mediated Synthesis of Monocyclic Aromatic Heterocycles

Transition Metal‐Catalyzed Synthesis of Monocyclic Five‐Membered Aromatic Heterocycles

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