Trihydroborates and Dihydroboranes Bearing a Pentacoordinated Phosphorus Atom: Double Ring Expansion To Balance the Coordination States

2017 ◽  
Vol 129 (21) ◽  
pp. 5976-5979 ◽  
Author(s):  
Naokazu Kano ◽  
Nathan J. O'Brien ◽  
Ryohei Uematsu ◽  
Romain Ramozzi ◽  
Keiji Morokuma
Keyword(s):  
Phosphorus Atom ◽  
Ring Expansion ◽  
Double Ring ◽  
Pentacoordinated Phosphorus

Trihydroborates and Dihydroboranes Bearing a Pentacoordinated Phosphorus Atom: Double Ring Expansion To Balance the Coordination States

2017 ◽  
Vol 56 (21) ◽  
pp. 5882-5885 ◽  
Author(s):  
Naokazu Kano ◽  
Nathan J. O'Brien ◽  
Ryohei Uematsu ◽  
Romain Ramozzi ◽  
Keiji Morokuma
Keyword(s):  
Phosphorus Atom ◽  
Ring Expansion ◽  
Double Ring ◽  
Pentacoordinated Phosphorus

Synthesis, Structure and Reactivities of Pentacoordinated Phosphorus–Boron Bonded Compounds

2020 ◽  
Author(s):  
Nathan O'Brien ◽  
Naokazu Kano ◽  
Nizam Havare ◽  
Ryohei Uematsu ◽  
Romain Ramozzi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ring Expansion ◽  
Bicyclic Compound ◽  
Compound A ◽  
Ligand System ◽  
Large Bulk ◽  
Rearrangement Reaction ◽  
Hydride Abstraction ◽  
Pentacoordinated Phosphorus ◽  
Acids And Bases

<div>The isolation and reactivities of two pentacoordinated phosphorus–tetracoordinated boron bonded compounds were</div><div>explored. A strong Lewis acidic boron reagent and electron-withdrawing ligand system were required to form the</div><div>pentacoordinated phosphorus state of the P–B bond. The first compound, a phosphoranyl-trihydroborate, gave a THF</div><div>stabilised phosphoranyl-borane intermediate upon a single hydride abstraction in THF. This compound could undergo a</div><div>unique rearrangement reaction, that involved a two-fold ring expansion, to give an unusual fused bicyclic compound or it</div><div>could act as a mono-hydroboration reagent. The hydroboration reactivity of the intermediate was found to be more reactive</div><div>towards alkynes over alkenes with good to moderate regioselectivity towards the terminal carbon. The second compound,</div><div>a phosphoranyl-triarylborate, was found to have a vastly different reactivity to the trihydroborate as it was highly stable</div><div>towards acids and bases. This is thought to be due to the large bulk around the P–B bond as shown in the crystal structure</div>

Double Ring Expansion from an Aromatic [18]Porphyrin(1.1.1.1) to an Antiaromatic [20]Porphyrin(2.1.2.1)

2016 ◽  
Vol 55 (28) ◽  
pp. 8095-8099 ◽  
Author(s):  
Masataka Umetani ◽  
Takayuki Tanaka ◽  
Taeyeon Kim ◽  
Dongho Kim ◽  
Atsuhiro Osuka
Keyword(s):  
Ring Expansion ◽  
Double Ring

Cascade Radical Cyclization-Fragmentation-Transannular-Ring Expansion Reactions Involving Oximes. A New Approach to Synthesis of Angular Triquinanes

1995 ◽  
Vol 48 (2) ◽  
pp. 381 ◽  
Author(s):  
GJ Hollingworth ◽  
G Pattenden ◽  
DJ Schulz
Keyword(s):  
Main Product ◽  
Ring Expansion ◽  
Radical Cyclization ◽  
One Pot ◽  
New Approach ◽  
Vinyl Bromide ◽  
Radical Intermediates ◽  
Double Ring ◽  
Radical Fragmentation ◽  
Aminyl Radical

Treatment of the acetylene-substituted cyclobutanone oxime ether (13) with (Me3Si)3SiH leads, in one pot, to the 5,6-bicyclic enone oxime (14) in 70% yield. It is suggested that the formation of (14) from (13) proceeds by way of a novel double ring expansion-transannulation process involving aminyl radical intermediates (see Scheme 3, below). By contrast, treatment of the cyclobutanone (3a) with Bu3SnH instead leads only to the product (11) of hydrostannylation of the acetylene unit in (3a). Neither (3a) nor (13) produced any of the expected bicyclo[3.3.0]octane products, viz. (5a) and (15), following treatment with silanes or stannanes. When a solution of the vinyl bromide-substituted cyclobutanone oxime (42) was irradiated with a sunlamp in the presence of (Me3Si)3SiH, the main product isolated was the triquinane (45) (38%) resulting from a cascade radical 6-exo-trig cyclization, aminyl radical fragmentation, 5-exo-trig radical transannulation, 5-exo-trig cyclization sequence.

The Cyclopropylalkylidenecyclopropane Thermal Double Ring Expansion. A Novel Route to the Bicyclo[5.3.1]undecane Skeleton of the AB Ring System of Taxanes1

1998 ◽  
Vol 120 (3) ◽  
pp. 605-606 ◽  
Author(s):  
Hong Liu ◽  
Craig A. Shook ◽  
James A. Jamison ◽  
Mohan Thiruvazhi ◽  
Theodore Cohen
Keyword(s):  
Ring Expansion ◽  
Ring System ◽  
Double Ring ◽  
Ab Ring

scholarly journals Isolation of a Bis-Iodurated Tetra-THF as a Trace Product from the Oxidation of Squalene with RuO4 and Its Double Ring Expansion to a Novel bis-THF-bis-THP Compound

Molecules ◽  
2011 ◽  
Vol 16 (7) ◽  
pp. 5362-5373 ◽  
Author(s):  
Vincenzo Piccialli ◽  
Sabrina Zaccaria ◽  
Roberto Centore ◽  
Angela Tuzi ◽  
Nicola Borbone ◽  
...  
Keyword(s):  
Ring Expansion ◽  
Double Ring

scholarly journals Synthesis, Structure and Reactivities of Pentacoordinated Phosphorus–Boron Bonded Compounds

2020 ◽  
Author(s):  
Nathan O'Brien ◽  
Naokazu Kano ◽  
Nizam Havare ◽  
Ryohei Uematsu ◽  
Romain Ramozzi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ring Expansion ◽  
Bicyclic Compound ◽  
Compound A ◽  
Ligand System ◽  
Large Bulk ◽  
Rearrangement Reaction ◽  
Hydride Abstraction ◽  
Pentacoordinated Phosphorus ◽  
Acids And Bases

The isolation and reactivities of two pentacoordinated<br>phosphorus–tetracoordinated boron bonded compounds were explored. A strong Lewis acidic boron reagent and electronwithdrawing ligand system were required to form the pentacoordinated phosphorus state of the P–B bond. The first compound, a phosphoranyl-trihydroborate, gave a THF stabilised phosphoranyl-borane intermediate upon a single hydride abstraction in THF. This compound could undergo a unique rearrangement reaction, which involved a two-fold ring expansion, to give a fused bicyclic compound or it could act as a mono-hydroboration reagent. The hydroboration reactivity of the intermediate was found to be more reactive towards alkynes over alkenes with good to moderate regioselectivity towards the terminal carbon. The second compound, a phosphoranyl-triarylborate, was found to have different reactivity as it was highly stable towards acids and bases. This is thought to be due to the large bulk around the P–B bond as shown in the crystal structure.<br>

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