Lactone synthesis based on atom transfer carbonylation

Article abstract of DOI:10.1021/ol9913441

(FORMULA PRESENTED) Five-to seven-membered lactones were prepared from ω-hydroxyalkyl iodides and CO by atom transfer carbonylation without the need for transition metal catalysts. The reaction proceeds via a hybrid radical/ionic mechanism in which the intramolecular alcoholysis of an ω-hydroxyacyl iodide, arising from atom transfer carbonylation, leads to the lactone.

Full text of DOI:10.1021/ol9913441

ORGANIC
LETTERS
2000
Vol. 2, No. 3
389-391
Lactone Synthesis Based on Atom
Transfer Carbonylation
Sergio Kreimerman, Ilhyong Ryu,* Satoshi Minakata, and Mitsuo Komatsu*
Department of Applied Chemistry, Graduate School of Engineering, Osaka UniVersity,
Suita, Osaka 565-0871, Japan
ryu@chem.eng.osaka-u.ac.jp
Received December 14, 1999
ABSTRACT
Five- to seven-membered lactones were prepared from ω-hydroxyalkyl iodides and CO by atom transfer carbonylation without the need for
transition metal catalysts. The reaction proceeds via a hybrid radical/ionic mechanism in which the intramolecular alcoholysis of an ω-hydroxyacyl
iodide, arising from atom transfer carbonylation, leads to the lactone.
Carbonylation reactions represent an important topic in
organic synthesis irrespective of whether the species under
consideration is an acylmetal or another acyl species such
as an acyl radical.1 Regarding the synthesis of lactones by
carbonylation, a number of metal-catalyzed systems have
been reported thus far.2-4,5
with ω-hydroxyalkyl iodides which leads to a novel method
for the synthesis of five- to seven-membered ring lactones.
As can be seen from the strategy in Scheme 1, the envisaged
protocol for lactone synthesis consists of three basic steps:
During the course of our studies in the development of
nontransition metal-based carbonylation methods,1b,c we
recently reported that atom transfer carbonylation, combined
with a judicious choice of both the radical initiation system
and the subsequent ionic quenching sequence, provides a
route to carboxylic acid esters and amides from alkyl iodides
and CO.6 In this Letter we report on an intramolecular
variation of a similar atom transfer carbonylation starting
Scheme 1. A Radical/Ionic Hybrid Approach for the
Synthesis of Lactones
(1) (a) Colquhoun, H. M.; Thompson, D. J.; Twigg, M. V. Carbonyl-
ation: Direct Synthesis of Carbonyl Compounds; Plenum: New York, 1991.
For reviews on radical carbonylation, see: (b) Ryu, I.; Sonoda, N. Angew.
Chem., Int. Ed. Engl. 1996, 35, 1050. (c) Ryu, I.; Sonoda, N.; Curran, D.
P. Chem. ReV. 1996, 96, 177. (d) Chatgilialoglu, C.; Crich, D.; Komatsu,
M.; Ryu, I. Chem. ReV. 1999, 99, 1991.
(2) For examples of transition metal-catalyzed carbonylation of vinyl
and aryl halo alcohols leading to lactones, see: (a) Aoyagi, S.; Hasegawa,
Y.; Hirashima, S.; Kibayashi, C. Tetrahedron Lett. 1998, 39, 2149. (b) Luo,
F.-T.; Wang, M.-W.; Liu, Y.-S. Heterocycles 1996, 43, 2725. (c) Suzuki,
T.; Uozumi, Y.; Shibasaki, M. J. Chem. Soc., Chem. Commun. 1991, 1593.
(d) Martin, L. D.; Stille, J. K. J. Org. Chem. 1982, 47, 3630. (e) Cowell,
A.; Stille, J. K. J. Am. Chem. Soc. 1980, 102, 4193. (f) Mori, M.; Chiba,
K.; Inotsume, N.; Ban, Y. Heterocycles 1979, 12, 921.
10.1021/ol9913441 CCC: $19.00 © 2000 American Chemical Society
Published on Web 01/20/2000

(i) radical carbonylation, (ii) iodine atom transfer, and (iii)
intramolecular ionic quenching of the generated acyl iodide
to afford the lactone, shifting the two reversible radical steps
(Scheme 1).7
Table 1. Lactone Synthesis via Atom Transfer Carbonylationa
Typically, 3-hydroxyalkyl iodide 1a (145.9 mg, 0.5 mmol)
was placed in a 50 mL stainless steel autoclave, lined with
a glass liner, with AIBN (24.6 mg, 0.15 mmol) and
allyltributyltin (16.6 mg, 0.05 mmol) as the radical initiator,6b
along with a mixture of hexane and MeCN (0.3 mL of each)
as solvent and Et3N (65.8 mg, 0.65 mmol) as base. The
autoclave was closed, purged twice with CO, pressurized
with 45 atm of CO, and then heated with stirring at 80 °C
for 12 h. Excess CO was discharged at room temperature
after the reaction. Washing the crude mixture with MeCN
+ -
(5 mL) followed by precipitation of the NHEt3 I in ether
(50 mL), filtration, evaporation of the filtrate, and column
chromatography on silica gel (ether-hexane; 0-30%) gave
γ-lactone 2a in 84% yield (Scheme 2).
Scheme 2
Some additional data on lactone syntheses are summarized
in Table 1. Using this method, γ-lactones were prepared
generally in good yields from the corresponding 3-iodo
alcohols and carbon monoxide (runs 1-7). Hydroxyalkyl
iodides which contain a perfluoroalkyl group in the â position
to the iodine-attached carbon worked well for this lactone
synthesis (runs 2, 5, and 7). Presumably due to the lower
propensity for iodine atom transfer, the conversion of the
primary alkyl iodide 1d to lactone 2d was slow (75%
conversion after 24 h, run 4). This resulted in the formation
of 2-ethyl-3-propyloxetane (11%) as a byproduct, which
likely arises via the SN2 type ring closure of 1d. One example
(3) For recent examples of transition metal-catalyzed carbonylation of
unsaturated alcohols leading to lactones, see: (a) Cao, P.; Zhang, X. J.
Am. Chem. Soc. 1999, 121, 7708. (b) Ogawa, A.; Kawabe, K.; Kawakami,
J.; Mihara, M.; Hirao, T. Organometallics 1998, 17, 3111. (c) Brunner,
M.; Alper, H. J. Org. Chem. 1997, 62, 7565. (d) Ukaji, Y.; Miyamoto, M.;
Mikuni, M.; Takeuchi, S.; Inomata, K. Bull. Chem. Soc. Jpn. 1996, 69,
735.
a General reaction conditions: 1 (05-1.0 mmol), AIBN (0.2-0.3 equiv),
allyltributyltin (0.1 equiv), Et3N (1.3 equiv), solvent (0.3-0.7 mL), CO
(45-90 atm), 80 °C, 12 h. b Yields after isolation by chromatography on
silica gel. c Reaction time: 24 h. d 75% conversion. e Xe lamp irradiation
f
was used for the initiation; reaction time 22 h. 1H NMR yield.
(4) For lactone synthesis by the Pd-catalyzed carbonylation of perflu-
orinated alkyl iodides, see: Urata, H.; Yugari, H.; Fuchikami, T. Chem.
Lett. 1987, 836.
(5) We have recently developed a new route for the synthesis of
δ-lactones by oxidative radical carbonylation of saturated alcohols, see:
(a) Tsunoi, S.; Ryu, I.; Okuda, T.; Tanaka, M.; Komatsu M.; Sonoda, N. J.
Am. Chem. Soc. 1998, 120, 8962. (b) Tsunoi, S.; Ryu, I.; Sonoda, N. J.
Am. Chem. Soc. 1994, 116, 5473.
shows that photoirradiation conditions6a can be used for the
lactone synthesis in place of a thermal initiator (run 6). The
scope of this synthetic strategy was extended successfully
to the synthesis of six- and seven-membered lactones as well
(runs 8 and 9).
(6) (a) Nagahara, K.; Ryu, I.; Komatsu, M.; Sonoda, N. J. Am. Chem.
Soc. 1997, 119, 5465. (b) Ryu, I. Nagahara, K.; Kambe, N.; Sonoda, N.;
Kreimerman, S.; Komatsu, M. Chem. Commun. 1998, 1953.
(7) A hybrid radical/ionic system is also useful for atom transfer reactions
other than carbonylation, see: (a) Joung, M. J.; Ahn, J. H.; Lee, D. W.;
Yoon, N. M. J. Org. Chem. 1998, 63, 2755. (b) Curran, D. P.; Ko, S.-B.
Tetrahedron Lett. 1998, 39, 6629.
Some of the substrates used in this study were prepared
by the carboiodination of olefinic alcohols,8 and this led us
to examine a more concise procedure for the synthesis of
lactones. Thus, fluoroalkyl-substituted lactones 2b and 2h
can be prepared from the corresponding alkenol and per-
390
Org. Lett., Vol. 2, No. 3, 2000

fluorohexyl iodide without the need to isolate compounds
Acknowledgment. We thank the Ministry of Education,
Science, Sports and Culture of Japan for financial support
(Grant-in Aid for Scientific Research on Priority Areas (No.
09238232)). S.K. also thanks Monbusho for providing a
scholarship.
1b and 1h, respectively (Scheme 3).9
Scheme 3
Supporting Information Available: Spectroscopy data
and analytical data of compounds 2a-2i. This material is
available free of charge via the Internet at http//pubs.acs.org.
OL9913441
(8) 1b, 1e, 1g, 1h, and 1i were prepared by carboiodination of the
respective olefinic alcohols, see: Takeyama, Y.; Ichinose, Y.; Oshima, K.;
Utimoto, K. Tetrahedron Lett. 1989, 30, 3159. 1a was prepared by
photoirradiation of a mixture (1/5/0.04) of ethyl iodoacetate, 3-buten-1-ol,
and Pd(PPh3)4. 1c and 1f were prepared by the reaction of 2-ethyl-1,3-
hexanediol and 1,3-butanediol, respectively, with diiodosilane, see: Keinan,
E.; Perez, D. J. Org. Chem. 1987, 52, 4846. 1d was prepared from the
same precursor as 1c by using a standard MsCl/NaI reaction.
In summary, we have presented herein a new carbonylation
method for the synthesis of lactones from ω-hydroxyalkyl
iodides and CO which does not require transition metal
catalysts. Further applications to other atom transfer car-
bonylation/ionic reaction sequences are currently being
investigated in our laboratory.
(9) For a similar reaction with the use of a Pd catalyst, see ref 4.
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