74752-51-5

Upstream product

• 67-64-1 acetone 
• 56892-26-3 1,1-dimethyl-2-phenyl-1-sila-2-cyclobutene 
• 67-56-1 methanol 
• 201789-85-7 4-methyl-3-phenyl-1-penten-3-ol 
• 591-50-4 iodobenzene 
• 4741-86-0 isopropylidenecyclopropane 
• 86108-38-5 Toluene-4-sulfonic acid 2,2-dimethyl-1-phenyl-but-3-enyl ester 

Relevant academic research and scientific papers

AN INTERPRETATION OF THE SUBSTITUENT EFFECT IN THE BLAISE REARRANGEMENT IN TERMS OF PI-ORBITALS

The migratory aptitude of the substituent groups in the Blaise rearrangement can be explained in terms of the pi-electronic properties of the groups in the highest occupied molecular orbitals.The rates of the rearrangement reaction with relation to the substituent groups were also rationally understood based on the energy levels of the molecular orbitals.

A new highly efficient three-component domino Heck-Diels-Alder reaction with bicyclopropylidene: Rapid access to spiro[2.5]oct-4-ene derivatives

Bicyclopropylidene (1) was found to surpass even methyl acrylate (17a) in its rate of undergoing carbopalladation with aryl- or alkenylpalladium species, leading to substituted allylidenecyclopropanes 5, 7 and 10, mostly in high yields (37-78%). These dienes and cross-conjugated trienes react in a Diels-Alder mode with dienophiles to give spiro[2.5]octenes 18a-Ph, 18b-Ph and 18a-Vin, respectively, in good yields (89, 69 and 65 %). The overall transformation can be achieved as a one-pot three-component reaction with a variety of dienophiles to furnish the domino Heck-Diels-Alder products 18 regioselectively in most cases in good to very high yields (49-100%). The reaction of 1 with iodobenzene (2-Ph) and 17a gave 18a-Ph in virtually quantitative yield - also on a gram scale - using only 1 mol% of catalyst, and even bromobenzene (22) gave 18a-Ph in 59% yield. Bicyclopropylidene (1), in the presence of palladium acetate/triphenylphosphane underwent rearrangement to allylidenecyclopropane (5-H), which in turn dimerized (73%) in the absence of other reaction partners, or could be trapped by diethyl fumarate (17c) to give the Diels-Alder adduct 18c-H in 45% yield. The coupling of oligoiodobenzenes with 1 and subsequent cyclo-addition could be extended to a multicomponent reaction. In this way, 1,4-diiodobenzene (37), 1 and an alkyl acrylate gave the products 38 of a twofold Heck-Diels-Alder reaction in up to 87% yield, 1,3,5-triiodobenzene (39) reacted in up to 72% yield and ultimately 1,2,4,5-tetraiodobenzene (41) gave the fourfold domino Heck-Diels-Alder product 42 in 47 % isolated yield, in a single operation in which 12 new carbon-carbon bonds were formed.

Stereochemistry of Carbenic 1,2-Vinyl Shifts

Various 1-phenylbut-3-enylidenes, (Ph)CCR2CH=CHR', were generated thermally and photolytically from tosylhydrazone (diazo) precursors. 1,2-Vinyl shifts, leading to 1,3-dienes, R′CH=CHC(Ph)=CR2, were found to predominate over γ-C-H insertion (R = Me) and to compete with 1,2-H shifts (R = H). Intramolecular addition to the double bond was detected in the case of R = R′ = Me. The resulting bicyclobutane is thermally stable and does not mediate the vinyl shift. Stereospecific migration of 1-propenyl groups (R′ = Me), with retention of configuration, was observed on thermolysis and direct photolysis of appropriate substrates. These data exclude the intervention of a triplet diradical and point to vinyl migration in the singlet manifold. Benzophenone-sensitized generation of the carbenes led to partial stereomutation but did not provide conclusive evidence for a triplet rearrangement (isomerization of the diene products could not be avoided under these conditions).

EVIDENCE FOR THE INTERMEDIACY OF 1,1-DIMETHYL-2-PHENYL-1-SILA-1,3-BUTADIENE IN THE PHOTOCHEMISTRY AND PYROLYSIS OF 1,1-DIMETHYL-2-PHENYL-1-SILA-2-CYCLOBUTENE

Photolysis of 1,1-dimethyl-2-phenyl-1-sila-2-cyclobutene (I) in methanol and methanol-O-d1 yields dimethylmethoxy(1-phenyl-2-propenyl)silane and dimethylmethoxy(1-d1-1-phenyl-2-propenyl)silane, respectively, as major products.These products may be formed by reaction of methanol or methanol-O-d1 with 1,1-dimethyl-2-phenyl-1-sila-1,3-butadiene.Gas phase pyrolysis of I and acetone or formaldehyde have also been studied.