Ozonolysis of Highly Methylated 1,2-Bis(methylene)cycloalkanes. Influence of the Methyl Substituents on the Course of the Reaction

Abstract

In the ozonolyses of highly methylated 3,3,4,4,5,5-hexamethyl-1,2-bis(methylene)cyclopentane (1a) and 3,3,6,6-tetramethyl-1,2-bis(methylene)cyclohexane (1b), the epoxidation competed with the cleavage of the C−C double bond, whereas only the latter process was observed in the case of the nonmethylated 1,2-bis(methylene)cycloalkanes 1c,d. Competition experiments revealed that the reactivity of the highly methylated 1,2-bis(methylene)cycloalkanes 1a,b is significantly smaller than that of the nonmethylated ones (1c,d), suggesting that the formation of the primary ozonides 2c,d occurs by a concerted 1,3-dipolar cycloaddition process.

Ozonolyses of 1-Alkyl-Substituted 3-Methylindenes. Remarkable Effects of the Substituent Steric Bulk and the Stereochemistry of the Carbonyl Oxide Intermediates on the Efficiency of Ozonide Formation

“…To understand the substituent effect on the direction of the cleavage of PO 4 , ozonolyses of indenes 1a − d were conducted in the presence of trifluoroacetophenone. In this respect, we previously reported that this highly electron-deficient ketone can capture carbonyl oxides very efficiently . When ozonolysis of 1,3-dimethylindene ( 1a ) was undertaken in ether in the presence of 1 equiv of trifluoroacetophenone, aldehyde ozonide 7a was obtained in 72% yield.…”

Ozonolyses of 3-Benzoyloxy- and 3-Trimethylsiloxy-Substituted 2-Phenylindenes in Methanol: Substituent-Dependent Modes of Capture of the Carbonyl Oxide Intermediates by the Solvent

“…3-(Benzoyloxy)-2-phenylindene ( 1 ) 4 was prepared by the reported method: white powder; mp 119−120 °C (from CH 2 Cl 2 −hexane); 1 H NMR δ 3.92 (s, 2 H), 7.0−8.3 (m, 14 H); IR 1740, 1255, 1245 cm -1 . The ozonolysis procedures have been previously described …”