99503-19-2

Upstream product

• 7333-63-3 4-bromobutylphosphonium bromide 
• 603-35-0 triphenylphosphine 

Downstream Products

• 3721-95-7 Cyclobutanecarboxylic acid 
• 53213-10-8 C₂₃H₂₁O₂P 
• 1120-56-5 methylidenecyclobutane 
• 6708-14-1 1,1'-bi(cyclobutylidene) 
• 86046-86-8 N-phenyl-1,2,3,6-tetrahydro-4-(diphenylphosphinyl)phthalimide 
• 86046-71-1 <1-(phenylseleno)cyclobutyl>triphenylphosphonium perchlorate 
• 86046-84-6 (cis-4,5-bis(ethoxycarbonyl)-1-cyclohexenyl)diphenylphosphine oxide 
• 86046-85-7 (trans-4,5-bis(ethoxycarbonyl)-1-cyclohexenyl)diphenylphosphine oxide 
• 1211936-52-5 C₁₃H₁₅BrO₂ 
• 86046-87-9 <1-(phenylseleno)cyclobutyl>triphenylphosphonium bromide 

Relevant academic research and scientific papers

Preparative-Scale Syntheses of Bicyclobutylidene, Methylenecyclobutane and Cyclobutanone

One-pot syntheses of bicyclobutylidene (3) and methylenecyclobutane (4) are described.Both 3 and 4 are valuable precursors of cyclobutanone (5).

Combined rhodium-catalyzed carbon-hydrogen activation and β-carbon elimination to access eight-membered rings

(Figure Presented) Enlargel C-H bond activation and β-carbon elimination are combined in a net intramolecular hydroacylation of alkylidenecyclobutanes and alkylideneazetidines in the presence of rhodium catalysts, affording eight-membered-ring compounds in high yield (see scheme). This study demonstrates the possibility of exploiting the strain energy of azetidines through β-carbon elimination in new transition-metal-catalyzed reactions.

Strain-Activated 1,3-Butadienes. Synthesis and Dienic Reactivity of Dicyclobutylideneethane

A synthesis of dicyclobutylideneethane (3) is described.An approach involving 1-(trimethylsilyl)-substituted cyclobutanes was first examined and shown not to be conducive for gaining access to this strained diene.A Wittig approach involving condensation of cyclobutylideneacetaldehyde (18) with cyclobutylidenetriphenylphosphorane (20) did deliver 3, whose dienic behavior toward several dienophiles was examined.The electronic spectrum of 3 resembles that of the bicyclohexylidene analogue and its relative reactivity in a representative Diels-Alder reaction was shown to be lower than that of 1.Despite the obvious steric congestion at its bonding centers, however, 3 has reasonable reactivity.Various approaches to cyclobutylidenecyclopropylideneethane (2) have been examined without success.These efforts are briefly summarized.

Synthesis, NMR Spectra, and Crystal Structure of Triphenylphosphonium Cyclobutylide, (C6H5)3P=C3

Crystalline samples of the title compound 2 were obtained from the reaction of (4-bromobutyl)triphenylphosphonium bromide (1) with sodium amide in liquid ammonia.The NMR data of this salt-free compound indicate significant deviation from a planar carbanion geometry usually typical of unstrained phosphonium ylides.An X-ray diffraction analysis confirms this for the crystalline state.The bond to the approximately tetrahedral onium centre is inclined to the neighbouring plane of the puckered cyclobutane ring (16.7 deg) by 19.3 deg.Yet, the ylidic P-C bond of 166.8(3) pm shows significant multiple bond character.