Natural Product Synthesis Using Multicomponent Reaction Strategies

Abstract

Toure ´and Hall Scheme 6. Synthesis of trans-Jasmonic Acid Using a Noyori-type 3CR, by Yamamoto and Co-workers 23 Scheme 7. Synthesis of Indanomycin Using a Noyori-type 3CR, by Burke and Co-workers 25 Scheme 8. Synthesis of Incarvilline and Incarvine Using a Noyori 3CR, by Kibayashi and Co-workers 26,28

Photochemical Electron Transfer Mediated Addition of Naphthylamine Derivatives to Electron-Deficient Alkenes

“…When compared to electrophilic substitution, one must also point out that the electrophilic site of α,β-unstaturated lactone is the β-position. Therefore, one should observe reaction at this position, which would also be in accordance with the Michael reaction as already mentionned. ,, The observed regiospecific α-addition in our reaction is due to previous protonation of the radical anion in the β-position as outlined in Schemes and . To explain this unusual selectivity, the structure of the radical anion must be discussed.…”

“…Two regioisomers 3a,b were obtained in a ratio of 9/1. Surprisingly when compared to the large majority of ground state reactions , of α,β-unsaturated carbonyl or carboxyl compounds, the addition of 1 occurred only in the α-position of furanone 2 . In similar reactions, the β-position of 2 is more electrophilic.…”

Photochemical Electron Transfer Mediated Addition of Naphthylamine Derivatives to Electron-Deficient Alkenes

“…When compared to electrophilic substitution, one must also point out that the electrophilic site of α,β-unstaturated lactone is the β-position. Therefore, one should observe reaction at this position, which would also be in accordance with the Michael reaction as already mentionned. ,, The observed regiospecific α-addition in our reaction is due to previous protonation of the radical anion in the β-position as outlined in Schemes and . To explain this unusual selectivity, the structure of the radical anion must be discussed.…”

“…Two regioisomers 3a,b were obtained in a ratio of 9/1. Surprisingly when compared to the large majority of ground state reactions , of α,β-unsaturated carbonyl or carboxyl compounds, the addition of 1 occurred only in the α-position of furanone 2 . In similar reactions, the β-position of 2 is more electrophilic.…”

Expeditious Total Synthesis of Hemiasterlin through a Convergent Multicomponent Strategy and Its Use in Targeted Cancer Therapeutics

“…X-ray crystallography analysis of 15 a was used to determine its absolute stereochemistry, which corresponded to the stereochemistry of hemiasterlin (Scheme 3 b). [50] The low diastereoselectivity observed in the Ugi-4CR step was similarly experienced in many previous total syntheses which utilised isocyanide-based multicomponent reactions (IMCRs), [32][33][34][35][36] where notable exceptions were when cyclic imines were used. [37,38] Consequently, several groups have reported the use of chiral phosphoric acids (CPAs) to induce enantioselectivity for IMCRs.…”

Expeditious Total Synthesis of Hemiasterlin through a Convergent Multicomponent Strategy and Its Use in Targeted Cancer Therapeutics

“…The low diastereoselectivity observed in the Ugi‐4CR step was similarly experienced in many previous total syntheses which utilised isocyanide‐based multicomponent reactions (IMCRs), [32–36] where notable exceptions were when cyclic imines were used [37, 38] . Consequently, several groups have reported the use of chiral phosphoric acids (CPAs) to induce enantioselectivity for IMCRs [39–42] .…”

Photochemical Electron Transfer Mediated Addition of Naphthylamine Derivatives to Electron-Deficient Alkenes

“…When compared to electrophilic substitution, one must also point out that the electrophilic site of α,β-unstaturated lactone is the β-position. Therefore, one should observe reaction at this position, which would also be in accordance with the Michael reaction as already mentionned. ,, The observed regiospecific α-addition in our reaction is due to previous protonation of the radical anion in the β-position as outlined in Schemes and . To explain this unusual selectivity, the structure of the radical anion must be discussed.…”

“…Two regioisomers 3a,b were obtained in a ratio of 9/1. Surprisingly when compared to the large majority of ground state reactions , of α,β-unsaturated carbonyl or carboxyl compounds, the addition of 1 occurred only in the α-position of furanone 2 . In similar reactions, the β-position of 2 is more electrophilic.…”

Expeditious Total Synthesis of Hemiasterlin through a Convergent Multicomponent Strategy and Its Use in Targeted Cancer Therapeutics

“…X-ray crystallography analysis of 15 a was used to determine its absolute stereochemistry, which corresponded to the stereochemistry of hemiasterlin (Scheme 3 b). [50] The low diastereoselectivity observed in the Ugi-4CR step was similarly experienced in many previous total syntheses which utilised isocyanide-based multicomponent reactions (IMCRs), [32][33][34][35][36] where notable exceptions were when cyclic imines were used. [37,38] Consequently, several groups have reported the use of chiral phosphoric acids (CPAs) to induce enantioselectivity for IMCRs.…”

Expeditious Total Synthesis of Hemiasterlin through a Convergent Multicomponent Strategy and Its Use in Targeted Cancer Therapeutics

“…The low diastereoselectivity observed in the Ugi‐4CR step was similarly experienced in many previous total syntheses which utilised isocyanide‐based multicomponent reactions (IMCRs), [32–36] where notable exceptions were when cyclic imines were used [37, 38] . Consequently, several groups have reported the use of chiral phosphoric acids (CPAs) to induce enantioselectivity for IMCRs [39–42] .…”

Photochemical Electron Transfer Mediated Addition of Naphthylamine Derivatives to Electron-Deficient Alkenes

“…When compared to electrophilic substitution, one must also point out that the electrophilic site of α,β-unstaturated lactone is the β-position. Therefore, one should observe reaction at this position, which would also be in accordance with the Michael reaction as already mentionned. ,, The observed regiospecific α-addition in our reaction is due to previous protonation of the radical anion in the β-position as outlined in Schemes and . To explain this unusual selectivity, the structure of the radical anion must be discussed.…”

“…Two regioisomers 3a,b were obtained in a ratio of 9/1. Surprisingly when compared to the large majority of ground state reactions , of α,β-unsaturated carbonyl or carboxyl compounds, the addition of 1 occurred only in the α-position of furanone 2 . In similar reactions, the β-position of 2 is more electrophilic.…”

Expeditious Total Synthesis of Hemiasterlin through a Convergent Multicomponent Strategy and Its Use in Targeted Cancer Therapeutics

“…X-ray crystallography analysis of 15 a was used to determine its absolute stereochemistry, which corresponded to the stereochemistry of hemiasterlin (Scheme 3 b). [50] The low diastereoselectivity observed in the Ugi-4CR step was similarly experienced in many previous total syntheses which utilised isocyanide-based multicomponent reactions (IMCRs), [32][33][34][35][36] where notable exceptions were when cyclic imines were used. [37,38] Consequently, several groups have reported the use of chiral phosphoric acids (CPAs) to induce enantioselectivity for IMCRs.…”

Expeditious Total Synthesis of Hemiasterlin through a Convergent Multicomponent Strategy and Its Use in Targeted Cancer Therapeutics

“…The low diastereoselectivity observed in the Ugi‐4CR step was similarly experienced in many previous total syntheses which utilised isocyanide‐based multicomponent reactions (IMCRs), [32–36] where notable exceptions were when cyclic imines were used [37, 38] . Consequently, several groups have reported the use of chiral phosphoric acids (CPAs) to induce enantioselectivity for IMCRs [39–42] .…”