An Arylative Ring Expansion Cascade of Fused Cyclobutenes via Short-Lived Intermediates with Planar Chirality

Arichi, Norihito; Yamada, Ken‐ichi; Yamaoka, Yousuke; Takasu, Kiyosei

doi:10.1021/jacs.5b06576

Cited by 41 publications

(18 citation statements)

References 32 publications

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“…Having developed ad irect approacht oa minocyclobutenol derivatives 5a-q and 6a-f as single isomers from ynamides, we were then interested in using the inherentr ing strain [11] of these highly functionalized four-membered carbocycles to perform as electivec arbon-carbon bond fragmentation as an ew entry to aminoalkenes. Attempts to generate ar ing-opened structure from 5c in refluxing benzene failed.…”

Section: Resultsmentioning

confidence: 99%

Direct Metal‐Free Entry to Aminocyclobutenes or Aminocyclobutenols from Ynamides: Synthetic Applications

Alcaide

Almendros

Lázaro‐Milla

2016

Chemistry A European J

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The [2+2] cycloaddition of ynamides with the highly polarized reagent Tf2 C=CH2 has been developed to regioselectively afford bis(triflyl)aminocyclobutenes in the absence of catalyst under mild conditions. Incidentally, with the ynamides bearing electron-rich aromatic rings at the C-terminal, an interesting reactivity switch was observed; a cyclization/hydroxylation sequence yielded 2-amino-3-(triflyl)cyclobut-2-enols. Aminocyclobutene construction with addition of alcohols resulted in the formation of aminocyclobutenyl ethers through a cyclization/hydroalkoxylation process. Moreover, the utility of functionalized aminocyclobutenes as precursors for further elaboration was demonstrated with the preparation of α-amino-β,γ-unsaturated ketones and 3-(triflyl)buta-1,3-dien-2-amines through 4 π-electrocyclic ring opening.

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Section: Resultsmentioning

confidence: 99%

Direct Metal‐Free Entry to Aminocyclobutenes or Aminocyclobutenols from Ynamides: Synthetic Applications

Alcaide

Almendros

Lázaro‐Milla

2016

Chemistry A European J

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“…In 2015, Takasu and co-workers reported an elegant domino arylative ring expansion of fused optically pure cyclobutenes 52 toward the synthesis of medium ring-fused trans-indolines 53. 21 The complete trans-diastereoselectivity of products was due to the planar rigidity of the trans diene derived from thermal 4-electrocyclic ring opening/ expansion of 52 (n = 1) (Scheme 18). The ring expansion of the unstable bicyclic units generating trans-diene int-B and its intermolecular trapping with the aryl-Pd complex…”

Section: Review Synthesismentioning

confidence: 99%

Pd-Catalyzed Domino Reactions Involving Alkenes To Access Substituted Indole Derivatives

et al. 2020

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Palladium-catalyzed domino reactions are advanced tools in achieving various nitrogen-containing heterocycles in an efficient and economical manner due to the reduced number of steps in the process. This review highlights recent advances in domino processes aimed at the synthesis of indole derivatives and polycyclic systems containing the indole nucleus in intra/intra- or intra/intermolecular reactions. In particular, we consider domino processes that involve a double bond in a step of the sequence, which allow the issue of regioselectivity in the cyclization to be faced and overcome. The different sections in this review focus on the synthesis of the indole nucleus and functionalization of the scaffold starting from different substrates that have been identified as activated starting materials, which involve a halogenated moiety or unactivated unsaturated systems. In the former case, the reaction is under Pd(0) catalysis, and in the second case a Pd(II) catalytic species is required and then an oxidant is necessary to reconvert the Pd(0) into the active Pd(II) species. On the other hand, the second method has the advantage that it uses easy available and inexpensive substrates.1 Introduction2 Indole Scaffold Synthesis2.1 Activated Substrates2.2 Unactivated Substrates3 Functionalization of Indole Scaffold3.1 Activated Substrates3.2 Unactivated Substrates4 Conclusions

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“…trans-Cyclononene derivatives, such as 100, can be prepared by a 4π electrocyclic ring opening reaction from a cis-fused cyclobutene (101), progressing via a cis,trans-siloxycycloalkadiene intermediate (102), with yields of up to 92 % (Scheme 34). [103,104] The reaction conditions were investigated and it was reported that the torquoselectivity during cyclobutene ring opening was highly controlled by an electron-donating siloxy-substituent, resulting in a proceeding Heck reaction to be regioselective on the distorted trans-double bond. A second synthesis of trans-cyclononene derivatives has been reported by Larionov and Corey, who used this compound in the synthesis of -Caryophyllene 103 (Scheme 35), which is a natural product that contains a trans-cyclononene core.…”

Section: Trans-cyclononenementioning

confidence: 99%

Highly Strained Unsaturated Carbocycles

et al. 2020

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Highly strained unsaturated carbocyclic rings are high‐energy compounds which are attracting increasing interest – not just for their peculiar structural and reactivity features – but also as modern chemical tools for bioorthogonal and in vivo chemistry, especially via inverse‐electron demand Diels–Alder (iEDDA) and strain‐promoted azide‐alkyne cycloaddition (SPAAC) reactions. This mini‐review covers two main classes of compounds: 3 to 10 membered‐ring cycloalkynes and trans‐cycloalkenes, including some examples of cyclic enynes, dienes and bridgehead alkenes. Their molecular properties, synthesis and reactivity are presented and discussed, with an emphasis on their functionalization and reactivity.

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An Arylative Ring Expansion Cascade of Fused Cyclobutenes via Short-Lived Intermediates with Planar Chirality

Cited by 41 publications

References 32 publications

Direct Metal‐Free Entry to Aminocyclobutenes or Aminocyclobutenols from Ynamides: Synthetic Applications

Direct Metal‐Free Entry to Aminocyclobutenes or Aminocyclobutenols from Ynamides: Synthetic Applications

Pd-Catalyzed Domino Reactions Involving Alkenes To Access Substituted Indole Derivatives

Highly Strained Unsaturated Carbocycles

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