Expedient Pyrrolizidine Synthesis by Propargylsilane Addition to<i>N</i>-Acyliminium Ions followed by Gold-Catalyzed α-Allenyl Amide Cyclization

Breman, Arjen C.; Dijkink, J.; Maarseveen, Jan H. van; Kinderman, Sape S.; Hiemstra, Henk

doi:10.1021/jo901393y

Cited by 51 publications

(22 citation statements)

References 21 publications

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“…Additional stabilization of the positive charge in C, e.g. when R'' = Ph (entries [17][18][19][20][21][22][23][24], further lowers the energy of both TS1 and C.…”

Section: Scheme 4 Synthesis Of N-acyliminium Ion Precursors 13-15mentioning

confidence: 99%

Synthesis of Bridged Heterocycles via Sequential 1,4- and 1,2-Addition Reactions to α,β-Unsaturated N-Acyliminium Ions: Mechanistic and Computational Studies

2016

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Novel tricyclic bridged heterocyclic systems can be readily prepared from sequential 1,4- and 1,2-addition reactions of allyl and 3-substituted allylsilanes to indolizidine and quinolizidine α,β-unsaturated N-acyliminium ions. These reactions involve a novel N-assisted, transannular 1,5-hydride shift. Such a mechanism was supported by examining the reaction of a dideuterated indolizidine, α,β-unsaturated N-acyliminium ion precursor, which provided specifically dideuterated tricyclic bridged heterocyclic products, and from computational studies. In contrast, the corresponding pyrrolo[1,2-a]azepine system did not provide the corresponding tricyclic bridged heterocyclic product and gave only a bis-allyl adduct, while more substituted versions gave novel furo[3,2-d]pyrrolo[1,2-a]azepine products. Such heterocyclic systems would be expected to be useful scaffolds for the preparation of libraries of novel compounds for new drug discovery programs.

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“…Additional stabilization of the positive charge in C, e.g. when R'' = Ph (entries [17][18][19][20][21][22][23][24], further lowers the energy of both TS1 and C.…”

Section: Scheme 4 Synthesis Of N-acyliminium Ion Precursors 13-15mentioning

confidence: 99%

Synthesis of Bridged Heterocycles via Sequential 1,4- and 1,2-Addition Reactions to α,β-Unsaturated N-Acyliminium Ions: Mechanistic and Computational Studies

2016

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“…These often undergo in situ protonolysis of the carbon-metal bond to give a simple double bond (Scheme 6.62). 71 The substrate, lactam 6.183, was prepared from malic acid using iminium ion chemistry. 70 The cyclization of allenic amides was employed in a synthesis of ent-retronecine 6.184 and other pyrrolizidine alkaloids (Scheme 6.64).…”

Section: Reactions Of Allenesmentioning

confidence: 99%

Electrophilic Alkene and Alkyne Complexes

Bates

2012

Organic Synthesis Using Transition Metals

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“…The method is applicable to a wide range of substrates, including different ring‐sized lactams. This sequence was shown to be useful for short total syntheses of the alkaloids heliotridine 36 and ent ‐retronecine 37 (Scheme ) 25…”

Section: N‐cyclizations Of Aminoallenesmentioning

confidence: 99%

Novel Cyclization Reactions of Aminoallenes

Alcaide

Almendros

2011

Adv Synth Catal

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The aminoallene moiety represents an excellent building block for heterocyclization reactions, affording a large number of cyclic structures containing different sized skeletons in a single step. This strategy has been studied under basic and electrophile-induced conditions. More recently, the use of transition metal catalysis has been introduced as an alternative relying on the activation of the allenic component. This overview focuses on the most recently developed cyclizations of aminoallenes along with remarkable early works accounting for the mechanism, as well as for the regio-and stereoselectivity of the cyclizations.

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Expedient Pyrrolizidine Synthesis by Propargylsilane Addition toN-Acyliminium Ions followed by Gold-Catalyzed α-Allenyl Amide Cyclization

Cited by 51 publications

References 21 publications

Synthesis of Bridged Heterocycles via Sequential 1,4- and 1,2-Addition Reactions to α,β-Unsaturated N-Acyliminium Ions: Mechanistic and Computational Studies

Synthesis of Bridged Heterocycles via Sequential 1,4- and 1,2-Addition Reactions to α,β-Unsaturated N-Acyliminium Ions: Mechanistic and Computational Studies

Electrophilic Alkene and Alkyne Complexes

Novel Cyclization Reactions of Aminoallenes

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