Ene reactions of conjugated dienes. 2. Dependence of rate on degree of hydrogen removed and s-cis or s-trans diene character

Abstract

was treated with 0.1 M CH3C02H. When analyzed by IR after 50 min, the C=0 band of CH3C02H (1710 cm"1) was absent and the solution was water-white. After an additional 10 min, a white precipitate (Ph2BOCOCH3) formed. Two equivalents of MeOH (0.2 M) were added and the mixture was shaken. The white solid quickly dissolved. IR analysis of the resulting solution revealed a strong band at 1710 cm"1 (CH3C02H) and a new strong band at 1325 cm"1 assigned to Ph2BOMe. Proof that the white precipitate was the mixed anhydride, and not simply a TPB(MeOH) complex, was obtained by isolation of the white precipitate obtained in the reaction of 0.050 g of TPB (0.2 M) with 11.4 gL (0.2 M) of CH3C02H in 1 cc of CC14. The KBr IR spectrum of the precipitate showed a weak broad band at 1720 cm"1, assigned to the C=0 group of Ph2BOCOCH3. The solvent was vacuum stripped and was analyzed by IR which showed peaks assigned to benzene (1475,1805, 1950, 3015, and 3040 cm"1), in addition to peaks from CC14 and a trace of CH3C02H. The assignment of the structure Ph2BOCOCH3 for the white precipitate was also confirmed by NMR analysis. The aromatic protons ( 7.75) and CH3 protons ( 2.2) gave an integral ratio 3.9/1 (theoretical 3.3). Finally, elemental analysis of the solid gave results more in agreement with the assigned mixed anhydride structure rather than a simple TPB(CH3C02H) complex. Anal. Caled for

Stereoselectivity in the Ene reaction of syn- and anti-1-(4-tert-butylcyclohexylidene)-4-tert-butylcyclohexane with singlet oxygen, nitrosyl hydride, nitrosoformaldehyde, 4-phenyl-1,2,4-triazol-3,5-dione, diethyl azodicarboxylate and methyl propiolate

“…121-124°C; 6 , (assigned by a 2D COSY experiment) 0.81 (9 H,s,3 Me), 0.86 (9 H,s,3 Me), 0.90-1.14 (4 H,complex,1.22 (1 H,m,1.32 (1 H,tt,m,2',1.88 (3 H,m,5,2.03 (1 H,dq,J 12.85,3.65,2.19 (2 H,m,2.38 (1 H,dq,J 13.16 and 3.15,),5.91 (1 H,dm J 5.33,6.83 1 H,s,OOH);6,24.04,24.45,24.51,25.20,27.17 (3C), 27.28, 27.62 (3C), 31.56, 31.79, 32.22, 32.27, 43.93, 47.90, 86.23, 129.07, 133.57; m/z (70 eV) (rel. intensity) 308 (M"), 275 (31), 57 (100); (Found: M + , 308.1717. C20H360, requires M , 308.271 5).…”

The effect of oxygen on the microwave-assisted synthesis of carbon quantum dots from polyethylene glycol

“…The formed CQDs contained oxygen functional groups such as phenolic and alcoholic hydroxyl groups, cyclic ether bonds, and carboxyl groups. 25,[36][37][38] In proposed specic pathways, ether bonds of PEG rst decomposed into free radicals that subsequently isomerized into alcohol hydroxyl groups, 25,38 and these alcohol hydroxyls formed double bonds as a result of an elimination reaction. Here, three conjugated double bonds converted into a six-membered ring by way of the Diels-Alder reaction.…”

“…Here, three conjugated double bonds converted into a six-membered ring by way of the Diels-Alder reaction. 37 At this time, according to this pathway, oxygen could interact with the a-C of the ether bond to form two free radicals, 36 which would have facilitated the aromatization of carbon atoms.…”

Regiocontrolled functionalization of seven-membered ring via nucleophilic cycloheptenyl-η3-allyltitanium complexes

“…Aldehydes lae, cycloheptatriene, titanocene dichloride, and isopropylmagnesium chloride (2 M solution in THF) were purchased from Aldrich Chemical Co. Aldehydes and cycloheptatriene were distilled under argon prior to use. 2,4,6-Octatriene was prepared by a reported procedure (14). 'H and I3c NMR spectra were recorded at 400 and 100.53 MHz, respectively.…”