Which allene double bond participates depends on the balance of electronic properties of both components (Scheme 38). For example, electron-poor allenes and electron-rich dienes combine at the allene 1,2 double bond < 82JCR(S)300 >, as do electron-rich allenes with electron-deficient dienes < 80TL4787 >.

2021年7月1日 · For allene, methyl-allene, and cyano-allene the reactivity varies upon altering the locations of the methyl group or cyano group. Thus, for all such reactions between the FLP and allene, methyl-allene, or cyano-allene, the FLP acts as a “diene” and the others as “dienophiles”.

2002年8月1日 · Allene oxides were known in chemistry well before they were discovered to occur in biology. The chemical oxidation of an allene group (two double bonds in series on consecutive carbons) was known to produce the allene oxide (allene epoxide), and the structure was of interest for its high reactivity and its potential for the development of new chemical syntheses [1].

2018年12月20日 · It was the first example for the allene 2,3-dicarbofunctionalization triggered by oxidative radical-medicated C3-addition of the terminal allene moiety and C–Br/C–H functionalization. This oxidative cyclization reaction was initiated by the generation of alkyl radical through the cleavage of α -C(sp 3 ) Br bond assisted by CuI and AgI upon ...

2024年11月1日 · In the proposed reaction mechanism, allene aziridination of 51 produced the aziridine intermediate XXXIV. The opening of the C–N bond yields a 2-aminoalkyl cation XXXV under heating, which undergoes a (4 + 3) reaction with the dienophile furan, resulting in a bridged cyclic compound with five chiral centers. In most cases, the products have d ...

2023年2月1日 · Allene oxide synthase (AOS), one of the key enzymes in the jasmonic acid (JA) biosynthesis pathway, has been well documented in enhancing plant adaptability to the external environment, but has not yet been reported in sugarcane (Saccharum spp.).

2019年8月1日 · Allene moiety is widespread in a great number of bioactive compounds, functional materials, and naturally occurring products [4]. Owing to the two orthogonal C C double bonds, allenes have exhibited high reactivity and chemical diversity in modern synthetic transformations [ …

1989年1月1日 · This was demon- strated with (R)-alcohol 10 (76 2% ee), obtained by reduction of the corresponding ketone with (R)- Alpineorane9 Implementation of the standard protocol furnished the (S) allene 11 = 76 C = 1.26 in acetone) in 81% yield.!O NMR analysis with the chiral shift reagent combination Ag(fod)b(hfc)3 showed the product to be 75 2% ee ...

Allene oxide (77) is also a reactive intermediate with an unusual structure, characterized by an epoxide ring with an exocyclic carbon–carbon double bond. Allene oxide cyclase and/or spontaneous hydrolysis acts to form well-known jasmonic acid, α- and γ-ketols, and racemic 12-oxo-(10,15Z)-phytodienoic acids, respectively [94–96].

Allene, H2C=C=CH2, is somewhat unusual in that it has two adjacent double bonds. Draw a picture showing the orbitals involved in the sigma and pi bonds of allene. Is the central carbon atom sp2- or sp-hybridized? What about the hybridization of the term; The allene molecule is linear. Determine the hybridization of each carbon atom.