Regiospecific reduction of oxetanes with lithium under aprotic conditions

Article abstract of DOI:10.1016/S0040-4039(99)02147-4

Substituted oxetanes have been found to give exclusively terminal alcohols by regiospecific ring-opening with lithium and biphenyl (cat.) in THF at reflux. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4039(99)02147-4

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 41 (2000) 1073–1074
Regiospecific reduction of oxetanes with lithium under aprotic
conditions
K. Rama and M. A. Pasha ∗
Department of Studies in Chemistry, Central College Campus, Bangalore University, Bangalore-560 001, India
Received 27 August 1999; accepted 17 November 1999
Abstract
Substituted oxetanes have been found to give exclusively terminal alcohols by regiospecific ring-opening with
lithium and biphenyl (cat.) in THF at reflux. © 2000 Elsevier Science Ltd. All rights reserved.
The synthetic applications of the cleavage of oxetane ring systems are well known. In this domain, the
reductive ring-opening of oxetanes leading to alcohols has not been studied in detail. The preparation of
alcohols by reducing oxetanes will be of great synthetic importance as different substituted alcohols
can be prepared from the respective oxetanes. This has been accomplished by various reagents like
LiAlH4,1–3 AlH3,2,3 Li-ethylenediamine,4 and H2/Raney nickel.5 However, the cost of the reagents and
the product ratio has limited the routine use of the above reagents.
While studying the action of lithium on different substituted oxetanes such as, aryl, arylalkyl, diaryl
and dialkyl oxetanes, we have found that lithium in the presence of biphenyl (cat.) is capable of
inducing the oxetanes to undergo regiospecific ring opening leading to the formation of terminal alcohols
exclusively under aprotic conditions (Scheme 1).
Scheme 1. R, R1-alkyl or aryl substituents
In a typical procedure, a mixture of oxetane, lithium metal and biphenyl (cat.) were heated in refluxing
THF for a period of 30 min. The reaction was monitored by TLC. After workup and purification on a
silica gel column, different alcohols were obtained and the results are listed in Table 1.
The reactions are general, reasonably fast, high yielding and free from side products. As oxetanes
can be readily obtained from carbonyl compounds,6 they can be used as important intermediates in the
preparation of terminal alcohols by extending the chain by two carbons.
∗
Corresponding author. E-mail: mapasha@hotmail.com (M. A. Pasha)
0040-4039/00/$ - see front matter © 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(99)02147-4
tetl 16075

1074
Table 1
Reduction of substituted oxetanes with lithium in THF
1. Experimental
The oxetanes were prepared from carbonyl compounds and identified from their PMR spectra.
Reduction of oxetanes. General procedure: 2-Phenyloxetane (10 mmol), lithium (2.2 g atom) and a
catalytic amount of biphenyl were stirred in dry THF (15 ml) at reflux. After the completion of the
reaction (15 min), water (5 ml) was added to the reaction mixture which was then extracted with ether
(3×10ml) and dried over anhydrous sodium sulphate. After evaporation of the ether, the product was
purified by silica gel chromatography to get 3-phenylpropan-1-ol.
References
1. Bach, T.; Frank, E.; Kristian, K. Liebigs Ann./Recl. 1997, 7, 1529.
2. Seyden-penne, J.; Schaal, C. Bull. De La Soc. Chim De France 1969, 10, 3653.
3. Schaal, C.; Seyden-penne, J. CR Acad. Sc. Paris. 1968, 266, 217.
4. Sauers, R. R.; Schinski, W.; Masch, M. M.; O’Hara, E.; Byrne, B. J. Org. Chem. 1973, 38, 622.
5. Sauers, R. R.; Whittle, J. A. J. Org. Chem. 1969, 34, 3579.
6. Okuma, K.; Tanaka, Y.; Kaji, S.; Ohta, H. J. Org. Chem. 1983, 48, 5133.