Detail of "926-66-9"

Reference

High-pressure-promoted [2 + 2] cycloadditions of imines with electron-rich alkenes

High-pressure-promoted [2 + 2] cycloadditions of imines with electron-rich alkenes. A simple route to azetidines and b-amino carbonyl compounds. Aben, R. W.Several substances are used for example 106419-26-5 which is its cas registry number. M.; Smit, R.; Scheeren, J. W. (Dep. Org. Chem., Univ. Nijmegen, Nijmegen 6525 ED, Neth.). J. Org. Chem., 52(3), 365-70 (English) 1987. CODEN: JOCEAH. ISSN: 0022-3263. DOCUMENT TYPE: Journal CA Section: 27 (Heterocyclic Compounds (One Hetero Atom)) The synthetic scope of high-pressure-promoted [2 + 2] cycloaddns. between imines and electron-rich alkenes was investigated. An azetidine was formed from the reaction of the strongly electron-rich 1-pyrrolidino-2-methylpropene and N-methyl- or N-phenylimines of benzaldehyde. The azetidines obtained decomp. slowly at normal pressure, even at room temp. Enamines with b-hydrogen do not yield azetidines but open products in the reaction with imines. Hydrolysis of the azetidines as well as the open products yield b-amino carbonyl compds. The high-pressure reaction combined with the hydrolysis was used as a one-pot process for the synthesis of a variety of b-amino carbonyl compds. The scope of the [2 + 2] cycloaddns. of the moderately electron-rich ketene acetals and the weakly electron-rich enol ethers with several imines could be greatly extended by using high pressure. The N-toluenesulfonylimine of benzaldehyde reacted with a variety of enol ethers having an a-hydrogen to give azetidines. A moderate to high stereoselectivity was found in these cycloaddns. The azetidine could be hydrolyzed to b-amino aldehydes. The stereochem. of these reactions is discussed. .

Electrophilic additions to highly reactive enol ethers

Electrophilic additions to highly reactive enol ethers. The particular role of resonance in determining the kinetic selectivity evidenced by extensive comparison of olefin bromination and hydration. Ruasse, Marie Francoise (Inst. Topol. Dyn. Syst., Univ. Paris VII, Paris 75005, Fr.). Isr. J. Chem., 26(4), 414-19 (English) 1985. CODEN: ISJCAT. ISSN: 0021-2148. DOCUMENT TYPE: Journal CA Section: 22 (Physical Organic Chemistry) The kinetic selectivity of aliph. enol ethers, EtOCR:CHR1 (R and R1 = H or Me), towards electrophiles, I2, Br2 and H3O+, is expressed by the kinetic effect of a Me substituent in the a position with respect to the ethoxy group, ka-Me/kH. As expected from the reactivity-selectivity principle, RSP, these selectivities are small, 16, 18 and 330, resp., as compared to those obsd. for less reactive olefins. However, a more general comparison of the selectivities of various XCH:CH2 olefins (X = Br, Me, Ph, OAc, OEt) reveals anomalies in their behavior with respect to the RSP: (i) enol ether iodination and bromination exhibit the same selectivity although their rate differ by 4 powers of ten, (ii) enol acetate and enol ether show similar selectivities in bromination but the rate of acetate is 3 ′ 105 times smaller than that of ether and (iii) in hydration the selectivities of these two olefins are similar to that of styrene although rates range over 7 powers of ten from styrene to enol ether. In contrast with what was previously obsd. for homogeneous series of R-substituted styrenes [Ph(R)C:CH2], there is no reactivity-selectivity relationship for electrophilic addns. to XCH:CH2 olefins. There is a parallelism, however, between the selectivities and the transition-state position estd. 4696-26-8 and 926-66-9 which are cas registry numbers of substances are two of reagents here. by the Broensted exponents for hydration and by the Winstein-Grunwald coeffs. for solvent effects on halogenations. These results are discussed in terms of different resonance effects on transition states and on reactivities which could arise from differences in the relative contributions of thermodn. and intrinsic kinetic (Hammond effects) factors on the selectivities. .