Influence of Some Factors on the Progress of a New Reaction in the Chemistry of Organoaluminum Compounds
- PDF / 655,063 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 97 Downloads / 161 Views
uence of Some Factors on the Progress of a New Reaction in the Chemistry of Organoaluminum Compounds M. P. Yakovlevaa,*, V. A. Vydrinaa, and G. Yu. Ishmuratova a
Ufa Institute of Chemistry, Ufa Federal Research Center, Russian Academy of Sciences, Ufa, 450054 Russia *e-mail: [email protected] Received March 10, 2020; revised March 24, 2020; accepted March 31, 2020
Abstract—We earlier discovered a new reaction in the chemistry of organoaluminum compounds (OACs), specifically, the formation of O-isobutyl acetals on low-temperature (–70°C) treatment of seven-membered lactones with a double (or more) molar amount of diisobutylaluminum hydride (DIBAH) in methylene chloride. To assess the boundaries for the formation of isobutyl acetals depending on the ring size, we involved in the low-temperature hydride reduction six-, eight-, and thirteen-membered lactones. To determine how the scope of the new reaction depends on the nature of the organoaluminum reagent, we tested triisobutylaluminum (TIBA). To determine how the formation of isobutyl acetals on low-temperature (–70°C) reduction with excess DIBAH in CH2Cl2 depends on whether the starting ester is cyclic or acyclic and, if the former is the case, on the ring size in the ester, we used the acyclic methyl octadecanoate as the starting compound. It was found that the new reaction in the chemistry of AOC with DIBAH as the reducer is characteristic only of seven-membered lactones and atypical of acyclic methyl octadecanoate and ricinoleate (i.e. acids with the carbon chain length more than 6). Keywords: lactones, oxepan-2-ones, acyclic esters, low-temperature reduction, diisobutylaluminum hydride, methylene chloride
DOI: 10.1134/S1070428020080047 Earlier [1–9] we discovered a new reaction in the chemistry of organoaluminum compounds (OACs): the formation of O-isobutyl acetals 1–9 on low-temperature (–70°C) treatment of seven-membered lactones 7S-10, 7R-10, and 11–18 with a double (or more) molar amount of diisobutylaluminum hydride (DIBAH) in methylene chloride (Scheme 1).
six-, eight-, and thirteen-membered lactones 19–21, respectively. Their reduction with a double molar amount of DIBAH in methylene chloride at–70°C gave mixtures of the corresponding alcohols 22 and 23 and hydroxyaldehydes 24–26. With a large excess (6 equiv) of DIBAH, no isobutyl acetals formed (Scheme 2).
Analysis of the resulting data raised a number of questions. Whether the reaction forming isobutyl acetals is characteristic exclusively of oxepan-2-ones or successful reaction may also take place with other types of lactones? Whether the reaction may not occur without DIBAH or isobutyl acetals will also form with other OACs, for example, triisobutylaluminum (TIBA)? Whether isobutyl acetals will form on the reduction of acyclic carboxylic esters? The present work was undertaken to address these questions.
To determine how the scope of the new reaction depends on the nature of the organoaluminum reagent, we employed triisobutylaluminum (TIBA). However, attempted reaction of TIBA with (–)-mentolactone
Data Loading...
