Total synthesis and absolute configuration of avenolide, extracellular factor in Streptomyces avermitilis

Article abstract of DOI:10.1038/ja.2011.90

The first total synthesis of extracellular factor, Avenolide, in Streptomyces avermitilis has been achieved using a convergent approach. The stereogenic centers in two key segments were installed using Sharpless epoxidation and dihydroxylation. This synthetic study allowed the determination of the absolute configuration of avenolide as 4S,10R, and yielded important information on its structure-activity relationship.

Full text of DOI:10.1038/ja.2011.90

The Journal of Antibiotics (2011) 64, 781–787
2011 Japan Antibiotics Research Association All rights reserved 0021-8820/11 $32.00
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ORIGINAL ARTICLE
Total synthesis and absolute configuration of avenolide,
extracellular factor in Streptomyces avermitilis
Miho Uchida1, Satoshi Takamatsu2,4, Shiho Arima1, Kiyoko T Miyamoto3, Shigeru Kitani3, Takuya Nihira3,
Haruo Ikeda2 and Tohru Nagamitsu1
The first total synthesis of extracellular factor, ‘‘Avenolide’’, in Streptomyces avermitilis has been achieved using a convergent
approach. The stereogenic centers in two key segments were installed using Sharpless epoxidation and dihydroxylation. This
synthetic study allowed the determination of the absolute configuration of avenolide as 4S,10R, and yielded important
information on its structure–activity relationship.
The Journal of Antibiotics (2011) 64, 781–787; doi:10.1038/ja.2011.90; published online 12 October 2011
Keywords: absolute configuration; avenolide; first total synthesis
INTRODUCTION
To undertake further biochemical properties of avenolide, the
In several streptomycete microorganisms, g-butyrolactones have determination of the absolute structure, access to an adequate supply
important, sometimes crucial, roles as extracellular factors in deter- of avenolide and the elucidation of the structure–activity relationship
mining the onset of secondary metabolite production and morpho- are required. We describe here the first total synthesis of avenolide,
logical differentiation. Up to date, the structures of all extracellular which represents significant progress towards these objectives.
factors are consisted of g-butyrolactones.1,2 A-factor is required for
streptomycin biosynthesis and sporulation in Streptomyces griseus1,2 RESULTS AND DISCUSSION
and virginia butanolide appears to control virginiamycin biosynthesis We first embarked on the synthesis of (4S,10R)-avenolide (1). As
in Streptomyces virginiae.3–5 Other studies g-butyrolactones include outlined in Scheme 1, our retrosynthetic strategy is convergent. We
IM-2 elicits production of showdomycin and minimycin in Strepto- speculated that 1 could be derived from epoxide 2 via ring closing
myces lavendulae FRI-53–5 and SCB1 also elicits the precocious metathesis, which itself could be constructed by the coupling of
production of actinorhodin in Streptomyces coelicolor A3(2).3–5
aldehyde 3 and iodide 4. This route should provide a concise route
Genome-sequenced Streptomyces avermitilis is an important indus- amenable to large-scale synthesis of avenolide as well as various
trial microorganism for the production of anthelmintic and insecti- avenolide analogs, including stereoisomers.
cidal macrocyclic lactone, avermectin, which is used as antiparasitic
The synthesis of 1 commenced with esterification of a commercially
agents in the medical, veterinary and agricultural fields. To identify available b-methallyl alcohol with p-anisic acid (Scheme 2). Subse-
the extracellular factor(s) controlling avermectin production in quent Sharpless dihydroxylation9,10 using (DHQ)2PHAL as a chiral
Streptomyces avermitilis, about 1 mg of the extracellular factor from ligand afforded 5 (93% ee).11–13 (The enantiomeric excess was
1000l of culture filtrate was isolated and purified by chromatographic determined by chiral HPLC analysis (condition: DAICEL CHIRAL-
separation steps.6 Since spectroscopic analyses of the extracellular PAK AS-3 (0.46 cm fꢀ25cm), 3:1 hexanes/2-propanol mobile phase
factor purified have elucidated that the factor is a new butenolide (flow rate at 1.0 ml per min) and detection at 254 nm (room
structure including two stereogenic centers (Scheme 1) but not g- temperature, rt)). Tosylation of the primary alcohol followed by
butyrolactone structure, the extracellular factor is named as ‘‘aveno- a substitution reaction with Me2CuCNLi2 and methanolysis gave
lide.’’ The absolute configuration could not be elucidated, however, diol 6. After acetal formation, DIBAL reduction and Parikh–Doering
due to the trace quantities isolated and the presence of contaminants. oxidation14 furnished the desired aldehyde 3.
Only the configuration of C4 (S, avenolide numbering) was proposed,
by comparison of the CD spectra of avenolide and similar butenolide available 1,5-pentanediol. Mono-TBS protection, TEMPO oxidation,
compounds.7,8
Wittig olefination with Ph3P¼CHCO2Et and DIBAL reduction
Another key intermediate 4 was derived from a commercially
1School of Pharmacy, Kitasato University, Tokyo, Japan; 2Kitasato Institute for Life Sciences, Kitasato University, Kanagawa, Japan and 3International Center for Biotechnology,
Osaka University, Osaka, Japan
4Current address: School of Pharmacy, Nihon University, 7-7-1 Narashinodai, Funabashi, Chiba 274-8555, Japan
Correspondence: Professor H Ikeda, Kitasato Institute for Life Sciences, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan.
E-mail: ikeda@ls.kitasato-u.ac.jp
or Professor T Nagamitsu, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan.
E-mail: nagamitsut@pharm.kitasato-u.ac.jp
Received 27 June 2011; revised 21 August 2011; accepted 30 August 2011; published online 12 October 2011

Total synthesis and absolute configuration of avenolide
M Uchida et al
782
O
H
OPMB
O
O
3
10
4
HO
+
9
O
OH
OPMB
O
1
THPO
I
O
(4S,10R)-avenolide (1)
2
4
Scheme 1 Retrosynthetic analysis of (4S,10R)-avenolide (1).
O
a,b
f,g,h
c,d,e
HO
PMBzO
OH
H
HO
OH
OH
OPMB
ꢀ-Methallyl
alcohol
5
6
3
i,j,k,l
m,n
HO
OTBS
THPO
OH
OH
HO
1,5-Pentanediol
7
8
o,p
THPO
I
4
OH
O
q
r,s
t
THPO
HO
4
OPMB
OPMB
9
10
O
O
O
x,y
u,v,w
HO
O
OH
OPMB
OPMB
O
O
O
O
2
11
(4S,10R)-avenolide (1)
Scheme 2 Reagents and conditions: (a) p-anisic acid, WSC, DMAP, CH2Cl2, rt, 99%; (b) K3Fe(CN)6, K2CO3, (DHQ)2PHAL, K2OsO4(OH)4, t-BuOH:H2O¼1:1, 0 1C,
quant., 93% ee; (c) p-TsCl, Et3N, Me3NꢁHCl, CH2Cl2, rt, 99%; (d) CuCN, MeLi, THF, 0 1C; (e) K2CO3, MeOH, rt, 90% (two steps); (f) p-methoxybenzaldehyde
dimethylacetal, PPTS, rt, CH2Cl2, quant.; (g) DIBAL, CH2Cl2, 01C, 87%; (h) SO3ꢁPy, DMSO, Et3N, CH2Cl2, rt, 89%; (i) NaH, TBSCl, THF, rt, 80%; (j) PhI(OAc)2,
TEMPO, CH2Cl2, rt, quant.; (k) Ph3P¼CHCO2Et, benzene, 801C, quant.; (l) DIBAL, CH2Cl2, 0 1C, quant.; (m) PPTS, DHP, CH2Cl2, 0 1C, quant.; (n) TBAF,
THF, rt, quant.; (o) MsCl, Et3N, Me3NꢁHCl, CH2Cl2, rt, 93%; (p) NaI, acetone, reflux, quant.; (q) t-BuLi, pentane, Et2O, ꢂ781C, then 3, ꢂ781C to 0 1C, 96%;
˚
(r) TPAP, NMO, CH2Cl2, rt, 97%; (s) PPTS, MeOH, rt, 99%; (t) (+)-DET, Ti(Oi-Pr)4, 4 A molecular sieves, t-BuOOH, CH2Cl2, ꢂ201C, 86%; (u) PPh3, I2,
imidazole, THF:MeCN¼4:1, rt, 80%; (v) NaI, Zn, MeOH, 901C, quant.; (w) acryloyl chloride, DMAP, Et3N, CH2Cl2, rt, 90%; (x) DDQ, CH2Cl2:H2O¼2:1, rt,
quant.; (y) Grubbs second-generation catalyst, CH2Cl2, 401C, quant.
afforded E-allyl alcohol 7.15,16 This was then converted to 8 by a used instead of (DHQ)2PHAL as the chiral ligand in Sharpless
two-step sequence of protecting group manipulations. Mesylation of asymmetric dihydroxylation (Scheme 3).
the primary alcohol of 8 followed by treatment with sodium iodide
gave rise to 4.
We next analyzed the synthetic 1 and 19 with a chiral HPLC column
(conditions: DAICEL CHIRALPAK IA-3 (0.46cm fꢀ25cm), EtOH
The aldehyde 3 was coupled with an alkyl lithium species derived from mobile phase (flow rate of 0.3 ml per min) and detection at 200 nm
halogen–lithium exchange of iodide 4 with t-BuLi to furnish alcohol 9 as (01C)). When a 1:1 mixture of 1 and 19 was injected onto the chiral
a diastereomeric mixture. TPAP oxidation and THP deprotection under HPLC system, the two diastereomers were completely resolved, as
acidic conditions afforded ketoalcohol 10. Subsequent Sharpless asym- shown in Figure 1a. Figures 1b and c show the HPLC chromatogram
metric epoxidation17 using (+)-DET as a chiral ligand gave the desired of 1 and 19, respectively. An authentic sample of the natural avenolide
epoxyalcohol 2. Transformation of the primary alcohol to iodide followed was also analyzed by HPLC, and its retention time was identical to that
by treatment with zinc yielded the corresponding allyl alcohol, which was of 1 as shown in Figure 1d. This result establishes the absolute
acylated with acryloyl chloride to provide 11. Finally, deprotection of the configuration of avenolide as 4S,10R.
PMB group by treatment with DDQ and ring closing metathesis18–22
using Grubbs second-generation catalyst afforded 1.
We also synthesized (4R,10R)-avenolide (22) and 10-deoxy avenolide
(28) for structure–activity relationship studies as shown in Scheme 4.
To determine the absolute configuration of 1, we also synthesized (The spectrum data of compounds in Schemes 3 and 4 are provided
(4S,10S)-avenolide (19), according to Scheme 2, with (DHQD)2PHAL as Supplementary information.) The synthesis of 22 was achieved
The Journal of Antibiotics

Total synthesis and absolute configuration of avenolide
M Uchida et al
783
O
a,b
f,g,h
c,d,e
HO
PMBzO
OH
OH
H
HO
OH
12
OH
13
OPMB
14
β-Methallyl
alcohol
O
q
r,s
t
THPO
HO
4
OPMB
OPMB
15
16
O
O
O
u,v,w
x,y
HO
O
OH
OPMB
OPMB
O
O
O
O
17
18
(4S,10S)-avenolide (19)
Scheme 3 Reagents and conditions: the same reaction conditions as those described in Scheme 2 were used, unless otherwise noted. (b) K3Fe(CN)6,
K2CO3, (DHQD)2PHAL, K2OsO4(OH)4, t-BuOH:H2O¼1:1, 0 1C, quant., 93% ee11–13; (q) t-BuLi, pentane, Et2O, ꢂ78 1C, then 14, ꢂ78 1C to 0 1C, 88%.
out following the same synthetic procedure as that developed for the
synthesis of 1 shown in Scheme 2.
Synthetic 1 demonstrated identical activity to that of natural 1.
In contrast, the rAvaR1-ligand activities of the C10-epimer (19), the
C4-epimer (22) and the 10-deoxy avenolide (28) demonstrated only
one-half, one twenty-fifth and one hundredth of the activity of the
natural product, respectively.6 It can therefore be concluded that the
stereochemistry at C4 and C10, and the presence of the hydroxyl group
at C10, are important to the activity of avenolide as a rAvaR1 ligand.
In conclusion, we have achieved the total synthesis of avenolide and
determined its absolute configuration. By extending the synthetic
methodology, we have generated a number of structural analogs,
which provide information on the structure–activity relationship of
avenolide. Further biological studies on the synthetic avenolide are
currently underway and will be reported in due course.
EXPERIMENTAL PROCEDURE
General
IR spectra were obtained using a Horiba FT-710 spectrophotometer (Horiba,
Kyoto, Japan). 1H and 13C-NMR spectra were obtained on Mercury-300 and
UNITY-400 spectrometers (Agilent Technologies, Santa Clara, CA, USA), and
chemical shifts are reported on the d scale, using TMS as an internal reference. MS
spectra were measured on JEOL JMS-700, JEOL JMS-T-100LP and JEOL JMS-
AX505HA spectrometers. Optical rotations were recorded on a JASCO DIP-1000
polarimeter (Jasco, Hachioji, Japan). Commercial reagents were used without
further purification unless otherwise indicated. Organic solvents were distilled and
˚
dried over molecular sieves (3 or 4 A). Reactions were performed in flame-dried
glassware under positive Ar pressure while stirring with a magnetic stirrer bar
unless otherwise indicated. Flash chromatography was performed on silica gel 60N
(spherical, neutral, particle size 40–50mm). TLC was performed on 0.25mm
Figure 1 HPLC chromatograms of natural and synthetic samples of
Merck silica gel 60 F254 plates (Merck, Darmstadt, Germany) and visualized by
avenolide (1 and 19). The abscissa axis indicates retention time (min).
UV (254 nm), and using phosphomolybdic acid and p-anisaldehyde as TLC stains.
(a) 1:1 mixture of 1 and 19; (b) 1; (c) 19; (d) natural avenolide.
(R)-2,3-Dihydroxy-2-methylpropyl-4-methoxybenzoate (5). To a solution of
b-methallyl alcohol (3.50 ml, 41.3mmol) in CH2Cl2 (83 ml) were added
according to our synthetic procedure for 1 as shown in Scheme 2, but
DMAP (504 mg, 4.13 mmol), N-(3-dimethylaminopropyl)-N¢-ethylcarbodiimide
using (ꢂ)-DET as the chiral ligand during Sharpless epoxidation. In
hydrochloride (WSC, 8.68 g, 45.4mmol) and p-anisic acid (6.91 g, 45.5mmol)
contrast, the synthesis of 28 required a slightly altered synthetic route.
A commercially available (S)-2-methyl-1-butanol was subjected to
at rt under N2. The reaction mixture was stirred for 2.5 h at rt. The reaction was
quenched with H2O and the aqueous phase was extracted with CH2Cl2.
TEMPO oxidation and dithioacetalization to afford 23,23 which was
coupled with iodide 4 to give 24. THP deprotection followed by
treatment with [bis(trifluoroacetoxy)iodo]benzene furnished ketone
The combined organic extracts were dried over anhydrous Na2SO4 and
concentrated in vacuo. The residue was purified by flash column chromato-
graphy (30:1 hexanes/EtOAc) to furnish the corresponding p-methoxybenzoate
25. The conversion of 25 into 10-deoxy avenolide (28) was carried (8.38 g, 99%) as a colorless oil.
The Journal of Antibiotics

Total synthesis and absolute configuration of avenolide
M Uchida et al
784
O
O
u,v,w
z
HO
10
O
OPMB
OPMB
O
O
20
21
O
x,y
OH
O
O
(4R,10R)-avenolide (22)
S
S
S
aa,bb
s,dd
cc
THPO
HO
S
(S)-2-Methyl-
1-butanol
23
24
O
O
O
t
u,v,w
HO
HO
O
O
O
25
26
27
O
x,y
O
O
10-deoxy avenolide (28)
Scheme 4 Reagents and conditions: the same reaction conditions as those described in Scheme 2 were used unless otherwise noted. (z) (ꢂ)-DET, Ti(Oi-Pr)4,
˚
4 A molecular sieves, t-BuOOH, CH2Cl2, ꢂ201C, 70%; (aa) PhI(OAc)2, TEMPO, CH2Cl2, rt; (bb) 1,3-pentanedithiol, BF3ꢁEt2O, ꢂ5 1C, 70% (two steps); (cc)
t-BuLi, THF:HMPA¼10:1, ꢂ78 1C, then 4, 82%; (dd) [bis(trifluoroacetoxy)iodo]benzene, CH3CN:H2O¼9:1, quant.
IR (KBr) 3082, 2939, 2842, 1715, 1607, 1511, 1457 cmꢂ1; 1H-NMR (400 MHz, flash column chromatography (1:1 hexanes/EtOAc) to afford the corresponding
CDCl3) d 8.03 (d, J¼9.0 Hz, 2H), 6.92 (d, J¼9.0 Hz, 2H), 5.06 (brs, 1H), 4.97
(brs, 1H), 4.72 (brs, 2H), 3.85 (s, 3H), 1.83 (brs, 3H); 13C-NMR (100 MHz,
CDCl3) d 166.0, 163.4, 140.2, 131.7, 122.6, 113.7, 112.7, 67.8, 55.4, 19.6; HRMS
(ESI+, TFA-Na) calcd for C12H14NaO3 229.0841 [M+Na]+, found m/z 229.0841. (d, J¼9.0Hz, 2H), 7.26 (d, J¼7.8 Hz, 2H), 6.90 (d, J¼8.8 Hz, 2H), 4.36
To a solution of the p-methoxybenzoate (4.00 g, 19.4mmol) in t-BuOH:H2O (d, J¼11.3Hz, 2H), 4.00 (d, J¼8.0 Hz, 2H), 3.88 (s, 3H), 2.35 (s, 3H), 1.28
(1:1, 194 ml) were added K3Fe(CN)6 (19.2 g, 58.2mmol), K2CO3 (8.05 g, (s, 3H); 13C-NMR (100MHz, CDCl3) d 166.1, 163.7, 145.2, 132.3, 131.8, 130.0,
58.2 mmol), K2OsO4(OH)4 (71.5mg, 0.19mmol) and (DHQ)2PHAL 128.0, 121.7, 113.7, 72.8, 70.8, 67.7, 55.5, 21.6, 21.6; HRMS (ESI+, TFA-Na)
(151mg, 0.19mmol) at 0 1C under N2. The reaction mixture was stirred for calcd for C19H22NaO7S 417.0984 [M+Na]+, found m/z 417.0971.
tosylate (2.57 g, 99%) as a colorless oil.
[a]D26 +1.94 (c 1.0 CHCl3); IR (KBr) 3519, 2982, 2842, 1712, 1604, 1511,
1462 cmꢂ1
;
1H-NMR (400MHz, CDCl3) d 7.87 (d, J¼9.0 Hz, 2H), 7.76
4.5h at 0 1C. The reaction was quenched with a saturated aqueous Na2S2O3 and
To a solution of CuCN (1.79 g, 19.9mmol) in THF (20 ml) was added MeLi
the aqueous phase was extracted with CH2Cl2. The combined organic extracts (1.07 M in diethyl ether, 37.3ml, 39.9 mmol) at ꢂ78 1C under Ar. After stirring
were dried over anhydrous Na2SO4 and concentrated in vacuo. The residue was for 20 min at 0 1C, a solution of the tosylate (1.57 g, 3.99 mmol) in THF (20 ml)
purified by flash column chromatography (5:1 hexanes/EtOAc) to afford 5 was added to the reaction mixture at ꢂ781C. The reaction was stirred for
(4.66 g, quant.) as a colorless oil. The enantiomeric excess (93% ee) of 5 was 30min at ꢂ781C, then allowed to warm to 0 1C and stirred for 20min. The
determined by chiral HPLC analysis (conditions: DAICEL CHIRALPAK AS-3 reaction was quenched with a saturated aqueous NH4Cl and the aqueous phase
(0.46 cm fꢀ25cm), mobile phase of 3:1 hexanes/2-propanol (flow rate of was extracted with EtOAc. The combined organic extracts were dried over
1.0ml per min) and detection at 254 nm (rt.)).
anhydrous Na2SO4 and concentrated in vacuo. The resulting residue was
[a]D26 ꢂ2.51 (c 1.0 MeOH); IR (KBr) 3478, 2976, 2842, 1706, 1606, 1512, dissolved in MeOH (40 ml) and K2CO3 (276 mg, 1.99mmol) was added. After
1462 cmꢂ1
;
1H-NMR (300MHz, CDCl3) d 7.98 (d, J¼9.1 Hz, 2H), 6.90 (d, stirring for 14 h at rt, the reaction mixture was concentrated in vacuo. The
J¼9.1 Hz, 2H), 4.36 (d, J¼11.3 Hz, 1H), 4.19 (d, J¼11.3 Hz, 1H), 3.85 (s, 3H), residue was purified by flash column chromatography (5:1 hexanes/EtOAc) to
3.57 (d, J¼11.6Hz, 1H), 3.46 (d, J¼11.4Hz, 1H), 2.95 (brs, 1H), 1.26 (s, 3H); give 6 (373mg, 90% over 2 steps) as a colorless oil.
13C-NMR (75.0MHz, CDCl3) d 166.9, 163.7, 131.8, 121.8, 113.8, 72.2, 68.0,
[a]D25+4.90 (c 1.0 CHCl3); IR (KBr) 3424, 2926, 2856, 1654, 1462 cmꢂ1; 1H-
66.9, 55.5, 21.3; HRMS (ESI+, TFA-Na) calcd for C12H16NaO5 263.0895 NMR (300 MHz, CDCl3) d 3.34 (d, J¼11.1Hz, 1H), 3.37 (d, J¼11.1Hz, 1H),
[M+Na]+, found m/z 263.0902.
3.10 (brs, 1H), 2.71 (brs, 1H), 1.50 (q, J¼7.3 Hz, 2H), 1.11 (s, 3H), 0.89
(t, J¼7.6 Hz, 3H); 13C-NMR (75.0 MHz, CDCl3) d 73.3, 69.3, 31.0, 22.4, 8.03.
(R)-2-Methylbutane-1,2-diol (6). To a solution of 5 (1.58 g, 6.59mmol) in
CH2Cl2 (66 ml) were added Et3N (1.80 ml, 13.2mmol), Me3NꢁHCl (63.0 mg, (R)-2-((4-Methoxybenzyl)oxy)-2-methylbutanal (3). To a solution of 6 (776 mg,
0.66 mmol) and TsCl (1.90 g, 9.89mmol) at rt under N2. The reaction mixture 7.46 mmol) in CH2Cl2 (30 ml) were added PPTS (93.7 mg, 0.37 mmol) and p-
was stirred for 3 h at rt. The reaction was quenched with H2O and the aqueous anisaldehyde dimethylacetal (1.27 ml, 7.46 mmol) at rt under N2. The reaction
phase was extracted with CH2Cl2. The combined organic extracts were dried mixture was stirred for 6 h at rt. The reaction was quenched with H2O and the
over anhydrous Na2SO4 and concentrated in vacuo. The residue was purified by
aqueous phase was extracted with EtOAc. The combined organic extracts were
The Journal of Antibiotics

Total synthesis and absolute configuration of avenolide
M Uchida et al
785
dried over anhydrous Na2SO4 and concentrated in vacuo. The residue was
The reaction mixture was stirred for 3 h at 801C. The reaction was concentrated
purified by flash column chromatography (50:1 hexanes/EtOAc) to afford the in vacuo. The residue was purified by flash column chromatography (80:1
corresponding p-methoxybenzylidene acetal (1.66 g, quant.) as a colorless oil. hexanes/EtOAc) to give the corresponding a,b-unsaturated ester (4.19 g,
[a]2D6 +1.40 (c 1.0 CHCl3); IR (KBr) 2969, 2929, 2874, 1614, 1515, quant.) as a colorless oil.
1461 cmꢂ1
;
1H-NMR (300MHz, CDCl3) d 7.42 (d, J¼8.8 Hz, 2H), 6.90 (d,
IR (KBr) 2933, 2859, 1724, 1655, 1468, 1259, 1101cmꢂ1 1H-NMR
;
J¼8.8Hz, 2H), 5.82 (s, 1H), 3.83 (s, 2H), 3.81 (s, 3H), 1.77–1.68 (m, 2H), 1.38 (400MHz, CDCl3) d 6.94 (dt, J¼15.7, 7.0Hz, 1H), 5.79 (dt, J¼15.7, 1.6 Hz,
(s, 3H), 1.00 (t, J¼7.5 Hz, 3H); 13C-NMR (75.0 MHz, CDCl3) d 160.4, 130.5, 1H), 4.16 (q, J¼7.2 Hz, 2H), 3.59 (t, J¼6.1 Hz, 2H), 2.21–2.19 (m, 2H),
128.1, 113.7, 103.6, 81.7, 75.4, 55.3, 31.2, 24.3, 8.54; HRMS (ESI+, TFA-Na) 1.52–1.49 (m, 4H), 1.26 (t, J¼7.1 Hz, 3H), 0.87 (s, 9H), 0.02 (s, 6H);
calcd for C13H19O3: 223.1334 [M+H]+, found m/z 223.1342.
13C-NMR (100 MHz, CDCl3) d 166.7, 149.1, 121.4, 62.7, 60.1, 32.2, 31.9,
To a solution of the p-methoxybenzylidene acetal (697mg, 3.14 mmol) in 25.9, 24.4, 18.3, 14.3, –5.32; HRMS (ESI+, TFA-Na) calcd for C15H30NaO3Si
CH2Cl2 (31 ml) was added DIBAL (1.02 M in hexanes, 9.00ml, 9.41mmol) at
0 1C under N2. After stirring for 1 h at 0 1C, the reaction was cautiously
309.1862 [M+Na]+, found m/z 309.1877.
To a solution of the a,b-unsaturated ester (1.82 g, 8.02mmol) in CH2Cl2
quenched with MeOH, diluted with CH2Cl2 and treated with celite (2.80 g) and (80 ml) was added DIBAL (1.02 M in hexanes, 15.7ml, 16.0 mmol) at 0 1C
Na2SO4ꢁ10H2O (2.80 g). The mixture was allowed to warm to rt and stirred for under N2. After stirring for 1 h, the reaction was cautiously quenched with
2 h. It was then filtered through a pad of celite and the filtrate was concentrated. MeOH, diluted with CH2Cl2 and treated with celite (5.90 g) and
The residue was purified by flash column chromatography (10:1 hexanes/ Na2SO4ꢁ10H2O (5.90 g). The mixture was allowed to warm to rt and stirred
EtOAc) to give the corresponding alcohol (615mg, 87%) as a colorless oil.
for 2 h, then filtered through a pad of celite and the filtrate was concentrated.
[a]2D6 +1.40 (c 1.0 MeOH); IR (KBr) 3444, 2970, 2936, 2879, 2839, 1613, The residue was purified by flash column chromatography (20:1 hexanes/
1514 cmꢂ1
;
1H-NMR (300MHz, CDCl3) d 7.27 (d, J¼8.7 Hz, 2H), 6.89 EtOAc) to furnish 7 (1.96 g, quant.) as a colorless oil.
(d, J¼8.7 Hz, 2H), 4.37 (s, 2H), 3.81 (s, 3H), 3.59 (d, J¼4.8Hz, 1H), 3.55
IR (KBr) 3339, 2932, 2859, 1467, 1254, 1101cmꢂ1 1H-NMR (300MHz,
;
(d, J¼5.0 Hz, 1H), 2.06 (brs, 1H), 1.66 (dq, J¼7.6, 2.3Hz, 1H), 1.23 (s, 3H), CDCl3) d 5.68–5.63 (m, 2H), 4.07 (d, J¼4.7 Hz, 2H), 3.60 (t, J¼6.3 Hz, 2H), 2.09–
0.94 (t, J¼7.5 Hz, 3H); 13C-NMR (75.0 MHz, CDCl3) d 159.0, 131.2, 129.0, 2.02 (m, 2H), 1.55–1.39 (m, 4H), 0.88 (s, 9H), 0.04 (s, 6H); 13C-NMR (75.0 MHz,
129.0, 113.9, 113.9, 77.8, 66.9, 63.3, 55.3, 27.8, 19.7, 8.09; HRMS (FAB, CDCl3) d 133.2, 129.1, 63.8, 63.0, 32.3, 31.9, 26.0, 26.0, 25.4, 18.4, ꢂ5.29; HRMS
m-NBA) calcd for C13H19O3 223.1334 [M+H]+, found m/z 223.1338.
(FAB, m-NBA) calcd for C13H29O2Si 245.1937 [M+H]+, found m/z 245.1934.
To a solution of the alcohol (239 mg, 0.94 mmol) in CH2Cl2 (9.4 ml) were
added DMSO (666 ml, 9.37 mmol), Et3N (1.31 ml, 9.37 mmol) and SO3ꢁpyr (E)-7-((Tetrahydro-2H-pyran-2-yl)oxy)hept-5-en-1-ol (8). To a solution of 7
(895 mg, 5.62 mmol) at rt under N2. The reaction mixture was stirred for 3.5 h (1.96 g, 8.02mmol) in CH2Cl2 (40 ml) were added PPTS (202mg, 0.80mmol)
at rt. The reaction was quenched with H2O and the aqueous phase was extracted and DHP (7.25 ml, 80.2 mmol) at 0 1C under N2. The reaction mixture was
with CH2Cl2. The combined organic extracts were dried over anhydrous Na2SO4 stirred for 6 h at 0 1C. The reaction was quenched with H2O and the aqueous
and concentrated in vacuo. The residue was purified by flash column chromato- phase was extracted with EtOAc. The combined organic extracts were dried
graphy (50:1 hexanes/EtOAc) to furnish 3 (188 mg, 89%) as a colorless oil.
[a]D22 +6.30 (c 1.0 CHCl3); IR (KBr) 2974, 2937, 2838, 1734, 1613,
over anhydrous Na2SO4 and concentrated in vacuo. The residue was purified by
flash column chromatography (50:1 hexanes/EtOAc) to afford the correspond-
1514 cmꢂ1; H-NMR (300 MHz, CDCl3) d 9.62 (s, 1H), 7.27 (d, J¼8.8 Hz, 2H), ing THP ether (2.63 g, quant.) as a colorless oil.
1
6.87 (d, J¼8.8 Hz, 2H), 4.39 (d, J¼17.6 Hz, 1H), 4.35 (d, J¼17.6 Hz, 1H), 3.78 (s,
IR (KBr) 2935, 2859, 1467, 1254, 1102 cmꢂ1; 1H-NMR (400MHz, CDCl3) d
3H), 1.81–1.63 (m, 2H) 1.29 (s, 3H), 0.91 (t, J¼7.6 Hz, 3H); 13C-NMR (75.0 MHz, 5.72–5.67 (m, 1H), 5.60–5.54 (m, 1H), 4.64–4.62 (m, 1H), 4.17 (ddd, J¼11.9,
CDCl3) d 205.3, 159.3, 130.4, 129.1, 113.9, 82.8, 65.9, 55.3, 27.7, 17.7, 7.30; HRMS
(FAB, m-NBA) calcd for C13H18NaO3 245.1154 [M+Na]+, found m/z 245.1162.
5.7, 1.2 Hz, 1H), 3.92 (ddd, J¼11.9, 5.7, 1.2 Hz, 1H), 3.90–3.84 (m, 1H), 3.59
(t, J¼6.5 Hz, 2H), 3.51–3.48 (m, 1H), 2.08–2.03 (m, 2H), 1.82–1.56 (m, 6H)
1.55–1.39 (m, 4H), 0.88 (s, 9H), 0.03 (s, 6H); 13C-NMR (100 MHz, CDCl3)
(E)-7-((tert-Butyldimethylsilyl)oxy)hept-2-en-1-ol (7). To a solution of NaH d 134.5, 126.3, 97.8, 67.9, 63.1, 62.3, 32.4, 32.1, 30.7, 26.0, 25.5, 25.3, 19.6, 18.4,
(1.94 g, 47.5mmol) in THF (158 ml) were added 1,5-pentanediol (5.00 ml, ꢂ5.26; HRMS (ESI+, TFA-Na) calcd for C18H36NaO3Si 351.2325 [M+Na]+,
47.5 mmol) and TBSCl (7.31 g, 47.5 mmol) at 0 1C under N2. The reaction found m/z 351.2331.
mixture was stirred for 5 min at 0 1C, then allowed to warm to rt and stirred for
To a solution of the THP ether (2.11 g, 6.42 mmol) in THF (64 ml) was added
2.5h. The reaction was quenched with H2O at 0 1C and the aqueous phase was TBAF (7.71 ml, 7.71 mmol) at rt under N2. The reaction mixture was stirred for
extracted with CH2Cl2. The combined organic extracts were dried over 4.5 h at rt. The reaction was quenched with H2O, and the aqueous phase was
anhydrous Na2SO4 and concentrated in vacuo. The residue was purified by extracted with CH2Cl2. The combined organic extracts were dried over anhydrous
flash column chromatography (5:1 hexanes/EtOAc) to afford the corresponding Na2SO4 and concentrated in vacuo. The residue was purified by flash column
TBS ether (8.30 g, 80%) as a colorless oil.
IR (KBr) 3359, 2933, 2860, 1468, 1254, 1100cmꢂ1
chromatography (1:1 hexanes/EtOAc) to give 8 (1.34 g, quant.) as a colorless oil.
IR (KBr) 3393, 2939, 2866, 1499, 1351, 1120cmꢂ1 1H-NMR (300MHz,
;
1H-NMR (400 MHz,
;
CDCl3) d 3.64–3.59 (m, 4H), 1.58–1.52 (m, 4H), 1.40–1.39 (m, 2H), 0.88 CDCl3) d 5.72–5.65 (m, 1H), 5.61–5.54 (m, 1H), 4.63–4.60 (m, 1H), 4.16 (ddd,
(s, 9H), 0.04 (s, 6H); 13C-NMR (100 MHz, CDCl3) d 63.2, 62.9, 32.5, 32.5, 26.0, J¼11.9, 5.5, 1.1 Hz, 1H), 3.90 (ddd, J¼11.9, 5.5, 1.1 Hz, 1H), 3.89–3.82
22.0, 18.4, –2.28; HRMS (FAB, m-NBA) calcd for C11H27O2Si 219.1780 (m, 1H), 3.61 (t, J¼6.5 Hz, 2H), 3.50–3.46 (m, 1H), 2.10–2.03 (m, 2H),
[M+H]+, found m/z 219.1776.
1.83–1.41 (m, 10H); 13C-NMR (75.0 MHz, CDCl3) d 133.0, 127.0, 97.8, 67.8,
To a solution of the TBS ether (4.00 g, 18.3mmol) in CH2Cl2 (183ml) were 62.7, 62.2, 32.2, 32.0, 30.6, 25.4, 25.2, 19.5; HRMS (FAB, m-NBA) calcd for
added iodobenzene diacetate (8.86 g, 27.5mmol) and TEMPO (573mg, C12H22NaO3 273.1467 [M+Na]+, found m/z 273.1467.
3.67 mmol) at rt under N2. The reaction mixture was stirred for 5 h at rt.
The reaction was quenched with an aqueous Na2S2O3 solution, and the (E)-2-((7-Iodohept-2-en-1-yl)oxy)tetrahydro-2H-pyran (4). To a solution of 8
aqueous phase was extracted with CH2Cl2. The combined organic extracts (657mg, 3.07mmol) in CH2Cl2 (31 ml) were added Et3N (855ml, 6.14mmol),
were dried over anhydrous Na2SO4 and concentrated in vacuo. The residue was Me3NꢁHCl (29.3 mg, 0.31mmol) and MsCl (356 ml, 4.61 mmol) at 0 1C under
purified by flash column chromatography (50:1 hexanes/EtOAc) to afford the N2. The reaction mixture was allowed to warm to rt and stirred for 3 h. The
corresponding aldehyde (3.96 g, quant.) as a colorless oil.
IR (KBr) 2952, 2933, 2859, 1727, 1468, 1254, 1102cmꢂ1
reaction was quenched with H2O and the aqueous phase was extracted with
1H-NMR CH2Cl2. The combined organic extracts were dried over anhydrous Na2SO4 and
;
(400 MHz, CDCl3) d 9.75 (s, 1H), 3.61 (t, J¼6.2 Hz, 2H), 2.46–2.42 (m, 2H), concentrated in vacuo. The residue was purified by flash column chromato-
1.70–1.65 (m, 2H), 1.57–1.51 (m, 2H), 0.87 (s, 9H), 0.03 (s, 6H); 13C-NMR graphy (10:1 hexanes/EtOAc) to afford the corresponding mesylate (837mg,
(100 MHz, CDCl3) d 203.7, 62.6, 43.6, 32.1, 25.9, 18.6, 18.3, –5.34; HRMS 93%) as a colorless oil.
1
(FAB, m-NBA) calcd for C11H25O2Si 217.1624 [M+H]+, found m/z 217.1618.
IR (KBr) 2940, 2866, 1354, 1174, 1121cmꢂ1, H-NMR (400MHz, CDCl3)
To a solution of the aldehyde (3.19 g, 14.8mmol) in benzene (148ml) was d 5.69–5.64 (m, 1H), 5.62–5.55 (m, 1H), 4.61–4.60 (m, 1H), 4.21 (t, J¼6.5 Hz,
added ethyl(triphenylphosphoranylidene)acetate (7.71 g, 22.1mmol) under N2. 2H), 4.17 (ddd, J¼12.0, 5.3, 1.2 Hz, 1H), 3.91 (ddd, J¼12.0, 5.3, 1.2 Hz, 1H),
The Journal of Antibiotics

Total synthesis and absolute configuration of avenolide
M Uchida et al
786
3.88–3.47 (m, 1H), 3.51–3.47 (m, 1H), 2.99 (s, 3H), 2.12–2.06 (m, 2H), 1.84– (d, J¼8.8 Hz, 2H), 5.69–5.58 (m, 2H), 4.32 (d, J¼10.7Hz, 1H), 4.29 (d,
1.46 (m, 10H); 13C-NMR (100MHz, CDCl3) d 133.0, 127.0, 97.8, 69.8, 67.6, J¼10.7Hz, 1H), 4.07–4.05 (m, 2H), 3.80 (s, 3H), 2.64 (dt, J¼7.3, 3.8 Hz,
62.2, 37.2, 31.5, 30.5, 28.5, 25.3, 24.7, 19.4; HRMS (ESI+, TFA-Na) calcd for 2H), 2.08–2.01 (m, 2H), 1.87–1.68 (m, 2H), 1.62–1.52 (m, 2H), 1.41–1.34
C13H24NaO5S 315.1242 [M+Na]+, found m/z 315.1206.
(m, 2H), 1.32 (s, 3H), 0.84 (t, J¼7.5Hz, 3H); 13C-NMR (75.0MHz, CDCl3)
To a solution of NaI (2.42 g, 16.2mmol) in acetone (216ml) was added the d 215.0, 159.0, 132.8, 130.7, 129.3, 128.6, 113.8, 113.8, 65.1, 63.7, 55.3, 36.8,
mesylate (3.15 g, 10.8 mmol) under N2. The reaction mixture was stirred for 32.1, 29.2, 28.8, 23.0, 19.9, 7.90; HRMS (ESI+, TFA-Na) calcd for C20H30NaO4
8.5h at reflux. After cooling to rt, the reaction was quenched with H2O and the 357.2042 [M+Na]+, found m/z 357.2031.
aqueous phase was extracted with EtOAc. The combined organic extracts were
dried over anhydrous Na2SO4 and concentrated in vacuo. The residue was (R)-8-((2S,3S)-3-(Hydroxymethyl)oxiran-2-yl)-3-((4-methoxybenzyl)oxy)-3-methyl-
˚
purified by flash column chromatography (80:1 hexanes/EtOAc) to give 4 octan-4-one (2). To a suspension of 4 A molecular sieves (134 mg) and (+)-DET
(3.49 g, quant.) as a colorless oil.
(177 ml, 1.03 mmol) in CH2Cl2 (5.0 ml) was added Ti(OiPr)4 (305 ml, 1.03 mmol)
IR (KBr) 2941, 2869, 1451, 1350, 1121 cmꢂ1; H-NMR (300MHz, CDCl3) at ꢂ20 1C under Ar. After stirring for 0.5 h, t-BuOOH (413 ml, 2.06 mmol)
d 5.71–5.54 (m, 2H), 4.61 (dd, J¼4.3, 2.9 Hz, 1H), 4.17 (ddd, J¼12.0, 5.4, was slowly added to the suspension at ꢂ20 1C and the resulting mixture was
1.0Hz, 1H), 3.91 (ddd, J¼12.0, 5.3, 1.2Hz, 1H), 3.88–3.82 (m, 1H), 3.53–3.47 stirred for 0.5 h. A solution of 10 (335 mg, 1.03 mmol) in CH2Cl2 (5.3 ml)
(m, 1H), 3.17 (t, J¼7.0 Hz, 2H), 2.10–2.03 (m, 2H), 1.87–1.44 (m, 10H); was then added dropwise to the reaction mixture and the mixture was stirred
13C-NMR (75.0MHz, CDCl3) d 133.5, 126.8, 97.8, 67.7, 62.3, 33.0, 31.2, 30.6, for 18 h at ꢂ20 1C. The reaction was quenched with Me2S (105ml, 1.43 mmol),
29.8, 25.5, 19.6, 6.80; HRMS (FAB, m-NBA): calcd for C12H21NaO2I 347.0484 diluted with CH2Cl2 and treated with celite (1.10 g) and Na2SO4ꢁ10H2O (1.10g).
1
[M+Na]+, found m/z 347.0484.
The suspension was allowed to warm to rt and then stirred for 2 h. The resulting
mixture was filtered through a pad of celite and the filtrate was concentrated
in vacuo. The residue was purified by flash column chromatography (5:1 hexanes/
EtOAc) to afford 2 (311 mg, 86%) as a colorless oil.
(3R,E)-3-((4-Methoxybenzyl)oxy)-3-methyl-11-((tetrahydro-2H-pyran-2-yl)oxy)un
dec-9-en-4-ol (9). To a solution of iodide 4 (844 mg, 3.8 mmol) in pentane
(22 ml) were added Et2O (8.2ml) and t-BuLi (1.55 M in pentane, 5.64 ml,
8.74 mmol) at ꢂ78 1C under Ar. After stirring for 15 min at ꢂ78 1C, a solution
of aldehyde 3 (1.35 g, 4.18 mmol) in Et2O (7.0 ml) was added. The reaction
[a]D28 ꢂ2.89 (c 1.0 CHCl3); IR (KBr) 3460, 2935, 1711, 1613, 1514, 1461 cmꢂ1
;
1H-NMR (400 MHz, CDCl3) d 7.27 (d, J¼8.8 Hz, 2H), 6.89 (d, J¼8.8 Hz, 2H),
4.33 (d, J¼10.7 Hz, 1H), 4.29 (d, J¼10.7 Hz, 1H), 3.90–3.82 (m, 1H), 3.80 (s, 3H),
mixture was allowed to warm to 0 1C and stirred for 3 h. The mixture was 3.64–3.62 (m, 1H), 2.96–2.88 (m, 2H), 2.66 (dt, J¼7.2, 2.6 Hz, 2H), 1.88–1.75 (m,
quenched with an aqueous NH4Cl solution and the aqueous phase was extracted
with EtOAc. The combined organic extracts were dried over anhydrous Na2SO4 13C-NMR (75.0 MHz, CDCl3) d 214.9, 159.0, 130.7, 128.6, 113.8, 84.9, 65.1, 61.7,
2H), 1.73–1.54 (m, 4H), 1.48–1.39 (m, 2H), 1.33 (s, 3H), 0.84 (t, J¼7.5 Hz, 3H);
and concentrated in vacuo. The residue was purified by flash column chromato-
graphy (15:1 hexanes/EtOAc) to afford 9 (1.54g, 96%) as a colorless oil.
58.4, 55.8, 55.3, 36.8, 31.4, 29.2, 25.7, 23.1, 20.0, 7.91; HRMS (ESI+, TFA-Na) calcd
for C20H30NaO5 373.1991 [M+Na]+, found m/z 373.1975.
[a]D22 +3.88 (c 1.0 CHCl3); IR (KBr) 3561, 2837, 1612, 1512, 1458 cmꢂ1
;
1H-NMR (300MHz, CDCl3) d 7.26 (d, J¼8.8 Hz, 2H), 6.88 (d, J¼8.8 Hz, 2H), (3S,9R)-9-((4-Methoxybenzyl)oxy)-9-methyl-8-oxoundec-1-en-3-yl acrylate (11). To
5.75–5.68 (m, 1H), 5.62–5.55 (m, 1H), 4.64 (dd, J¼3.5, 3.0 Hz, 1H), 4.34 (s, 2H),
4.19 (ddd, J¼11.9, 5.6, 1.1 Hz, 1H), 3.92 (ddd, J¼11.9, 6.7, 0.8 Hz, 1H), 3.88–3.82
(m, 1H), 3.80 (s, 3H), 3.68–3.64 (m, 1H), 3.54–3.47 (m, 1H), 2.17–2.05 (m, 2H),
a solution of 2 (195 mg, 0.56 mmol) in THF:MeCN (4:1, 5.6 ml) were added
imidazole (227 mg, 3.33 mmol), PPh3 (437 mg, 1.67 mmol) and I2 (423 mg,
1.67 mmol) at 0 1C under N2. After warming to rt, the reaction mixture was
1.86–1.15 (m, 14H), 1.14 (s, 3H), 0.92 (t, J¼7.5 Hz, 3H); 13C-NMR (75.0 MHz, stirred for 1h. The reaction was quenched with H2O and the aqueous phase
CDCl3) d 159.0, 134.9, 131.0, 128.9, 126.1, 113.8, 97.7, 80.1, 73.9, 67.8, 62.8, 62.2, was extracted with CH2Cl2. The combined organic extracts were dried over
55.2, 32.3, 30.8, 30.6, 29.6, 29.1, 26.5, 26.4, 25.4, 19.5, 17.6, 14.1, 7.34; HRMS
anhydrous Na2SO4 and concentrated in vacuo. The residue was purified by flash
(ESI+, TFA-Na) calcd for C25H40NaO5 443.2773 [M+Na]+, found m/z 443.2753. column chromatography (30:1 hexanes/EtOAc) to give the corresponding iodide
(204 mg, 80%) as a colorless oil.
(R,E)-11-Hydroxy-3-((4-methoxybenzyl)oxy)-3-methylundec-9-en-4-one
[a]D25 +6.68 (c 1.0 CHCl3); IR (KBr) 2936, 2864, 1712, 1613, 1514,
(10). To a solution of 9 (674mg, 1.60mmol) in CH2Cl2 (16 ml) were 1460 cmꢂ1
;
1H-NMR (300MHz, CDCl3) d 7.28 (d, J¼8.8 Hz, 2H), 6.90
˚
added NMO (380 mg, 3.21 mmol), TPAP (28.2 mg, 0.08 mmol) and 4 A
(d, J¼8.8 Hz, 2H), 4.33 (d, J¼10.7 Hz, 1H), 4.30 (d, J¼10.7 Hz, 1H), 3.80 (s,
molecular sieves (674 mg) at rt under N2. The reaction mixture was stirred 3H), 3.26–3.21 (m, 1H), 3.05–3.00 (m, 1H), 2.97 (ddd, J¼4.7, 2.3 Hz, 1H), 2.79
for 1.5h at rt. The mixture was filtered through a pad of celite. The filtrate was (ddd, J¼5.6, 5.5, 1.9Hz, 1H), 2.66 (dt, J¼7.0, 3.8 Hz, 2H), 1.88–1.66 (m, 2H),
diluted with H2O and extracted with CH2Cl2 followed by EtOAc. The combined 1.64–1.52 (m, 4H), 1.48–1.40 (m, 2H), 1.33 (s, 3H), 0.84 (t, J¼7.5 Hz, 3H);
organic extracts were dried over anhydrous Na2SO4 and concentrated in vacuo. 13C-NMR (75.0 MHz, CDCl3) d 214.7, 159.1, 130.7, 128.6, 113.9, 84.9, 65.1,
The residue was purified by flash column chromatography (40:1 hexanes/ 62.4, 58.3, 36.8, 31.6, 29.2, 25.6, 23.2, 20.0, 7.93, 5.02; HRMS (ESI+, TFA-Na)
EtOAc) to afford the corresponding ketone (652 mg, 97%) as a colorless oil.
[a]D27 +7.80 (c 1.0 CHCl3); IR (KBr) 2940, 2868, 1712, 1613, 1514, 1459 cmꢂ1
calcd for C20H29INaO4 483.1008 [M+Na]+, found m/z 483.1012.
;
To a solution of the iodide (163mg, 0.35 mmol) in MeOH (707ml) were
1H-NMR (300 MHz, CDCl3) d 7.27 (d, J¼8.8 Hz, 2H), 6.89 (d, J¼8.8 Hz, 2H), added NaI (133mg, 0.88mmol) and Zn (69.4 mg, 1.06mmol) under N2. After
5.71–5.51 (m, 1H), 5.60–5.51(m, 1H), 4.63–4.25 (m, 1H), 4.32 (d, J¼10.7 Hz, 1H), stirring for 2.5 h at 901C, the reaction was quenched with H2O and the aqueous
4.28 (d, J¼10.7 Hz, 1H), 4.17 (ddd, J¼12.0, 5.5, 1.1 Hz, 1H), 3.91 (ddd, J¼12.0, phase was extracted with CH2Cl2. The combined organic extracts were dried
5.5, 1.1 Hz, 1H), 3.88–3.83 (m, 1H) 3.80 (s, 3H), 3.80–3.46 (m, 1H), 2.64 (dt, over anhydrous Na2SO4 and concentrated in vacuo. The residue was purified by
J¼7.3, 3.5 Hz, 2H), 2.09–2.01 (m, 2H), 1.87–1.35 (m, 10H), 1.42–1.35 (m, 2H),
flash column chromatography (10:1 hexanes/EtOAc) to afford the correspond-
1.32 (s, 3H), 0.84 (t, J¼7.5 Hz, 3H); 13C-NMR (75.0 MHz, CDCl3) d 214.9, 159.0, ing allyl alcohol (118mg, quant.) as a colorless oil.
134.2, 130.7, 128.6, 126.4, 113.8, 97.8, 84.9, 67.8, 65.1, 62.6, 55.3, 36.8, 32.2, 30.7,
[a]D26 +8.93 (c 1.0 CHCl3); IR (KBr) 3518, 3075, 2941, 1710, 1613,
29.3, 28.8, 25.5, 23.0, 19.9, 19.6, 7.89; HRMS (ESI+, TFA-Na) calcd for 1513 cmꢂ1
;
1H-NMR (300MHz, CDCl3) d 7.28 (d, J¼8.8 Hz, 2H), 6.89
C25H38NaO5 441.2617 [M+Na]+, found m/z 441.2605.
(d, J¼8.8 Hz, 2H), 5.90–5.79 (m, 1H), 5.20 (ddd, J¼17.2, 1.4 Hz, 1H), 5.09
To a solution of the ketone (597mg, 1.43 mmol) in MeOH (14 ml) was (ddd, J¼10.4, 1.4 Hz, 1H), 4.32 (d, J¼10.8Hz, 1H), 4.29 (d, J¼10.8Hz, 1H),
added PPTS (359mg, 1.43mmol) at rt under N2. The reaction mixture was
stirred for 5 h at rt. The reaction was quenched with H2O and the aqueous (m, 2H), 1.61–1.34 (m, 6H), 1.32 (s, 3H), 0.84 (t, J¼7.5 Hz, 3H); 13C-NMR
phase was extracted with CH2Cl2. The combined organic extracts were dried (75.0 MHz, CDCl3) d 215.0, 159.0, 141.1, 130.7, 128.6, 128.6, 114.5, 113.8,
4.12–4.05 (m, 1H) 3.80 (s, 3H), 2.65 (dt, J¼7.3, 4.3 Hz, 2H), 1.87–1.68
over anhydrous Na2SO4 and concentrated in vacuo. The residue was purified by
flash column chromatography (10:1 hexanes/EtOAc) to afford 10 (475mg, TFA-Na) calcd for C20H30NaO4 357.2042 [M+Na]+, found m/z 357.2025.
99%) as a colorless oil. To a solution of the allyl alcohol (179 mg, 0.53mmol) in CH2Cl2 (5.3ml)
113.8, 84.8, 72.9, 65.1, 55.2, 36.8, 36.8, 29.2, 25.0, 23.2, 20.0, 7.84; HRMS (ESI+,
[a]D22 +4.35 (c 1.0 CHCl3); IR (KBr) 3561, 3298, 2866, 1712, 1612, 1513, were added acryloyl chloride (65 ml, 0.80 mmol), Et3N (223ml, 1.60mmol) and
1458 cmꢂ1
;
1H-NMR (300MHz, CDCl3) d 7.27 (d, J¼8.8 Hz, 2H), 6.89 DMAP (cat.) at 0 1C under N2. After stirring for 1 h at rt, the reaction was
The Journal of Antibiotics

Total synthesis and absolute configuration of avenolide
M Uchida et al
787
quenched with H2O and the aqueous phase was extracted with CH2Cl2. 24.7, 23.1, 15.9, 11.7; HRMS (ESI+, TFA-Na) calcd for C13H20NaO3 247.1310
The combined organic extracts were dried over anhydrous Na2SO4 and [M+Na]+, found m/z 247.1322.
concentrated in vacuo. The residue was purified by flash column chromato-
graphy (30:1 hexanes/EtOAc) to afford 11 (187mg, 90%) as a colorless oil.
Evaluation of biological activity
[a]2D4 +6.32 (c 1.0 CHCl3); IR (KBr) 2940, 1718, 1615, 1514, 1460cmꢂ1
;
Biological activity of the compounds were measured either as the DNA
dissociation activity from the rAvaR1–DNA complex in gel-shift experiment
or by avermectin-inducing activity of S. avermitilis aco mutant.6
1H-NMR (300MHz, CDCl3) d 7.27 (d, J¼8.8 Hz, 2H), 6.89 (d, J¼8.8Hz, 2H),
6.40 (dd, J¼17.3, 1.5 Hz, 1H), 6.12 (dd, J¼17.3, 10.4Hz, 1H), 5.84–5.73
(m, 2H), 5.31–5.27 (m, 1H), 5.24 (ddd, J¼17.3, 9.3, 1.3 Hz, 1H), 5.16 (ddd,
J¼10.5, 5.9, 1.2 Hz, 1H), 4.32 (d, J¼10.7Hz, 1H), 4.29 (d, J¼10.7Hz, 1H), 3.81
(s, 3H), 2.64 (dt, J¼7.3, 3.9 Hz, 2H), 1.87–1.53 (m, 8H), 1.32 (s, 3H), 0.84
(t, J¼7.5 Hz, 3H); 13C-NMR (75.0 MHz, CDCl3) d 214.8, 165.5, 159.0, 136.3,
130.7, 130.6, 128.7, 128.6, 116.8, 113.8, 113.8, 84.5, 74.8, 65.1, 55.3, 36.8, 34.1,
29.2, 24.8, 23.3, 20.0, 7.90; HRMS (ESI+, TFA-Na) calcd for C23H32NaO5
411.2147 [M+Na]+, found m/z 411.2136.
ACKNOWLEDGEMENTS
This work was supported by a Grant-in-Aid for Scientific Research on
Innovative Areas from MEXT Japan (HI), from JSPS 20310122 (HI) and from
the Institute for Fermentation, Osaka, Japan (HI). We thank N Sato and
K Nagai of Kitasato University for measuring NMR and MS spectra.
(4S,10R)-avenolide (1). To
a solution of 11 (187mg, 0.48mmol) in
CH2Cl2:H2O (20:1, 4.6 ml) was added DDQ (146mg, 0.53mmol) at rt under
N2. After stirring for 1 h at rt, the reaction was quenched with H2O and the
aqueous phase was extracted with CH2Cl2. The combined organic extracts were
dried over anhydrous Na2SO4 and concentrated in vacuo. The residue was
purified by flash column chromatography (40:1 hexanes/EtOAc) to give the
corresponding alcohol (159mg, quant.) as a colorless oil.
1
2
Horinouchi, S. & Beppu, T. Autoregulators. in Genetics and Biochemistry of Antibiotic
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Roberts, D.McL.) 177–196 (Society for General Microbiology, Cambridge, 1999).
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a new butyrolactone autoregulator from Streptomyces sp. FRI-5. J. Ferment. Bioeng.
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3
4
[a]2D5 ꢂ8.51 (c 1.0 CHCl3); IR (KBr) 3486, 2936, 2863, 1721, 1637,
1459 cmꢂ1
;
1H-NMR (300 MHz, CDCl3) d 6.41 (dd, J¼17.3, 1.5 Hz, 1H),
6.12 (dd, J¼17.3, 10.4Hz, 1H), 5.85–5.73 (m, 2H), 5.34–5.16 (m, 2H), 3.82
(brs, 1H), 2.54–2.45 (m, 2H), 1.75–1.59 (m, 8H), 1.33 (s, 3H), 0.79
(t, J¼7.4 Hz, 3H); 13C-NMR (75.0 MHz, CDCl3) d 214.3, 165.5, 136.2, 130.8,
128.6, 116.9, 78.9, 74.6, 35.5, 34.0, 32.3, 25.1, 24.7, 23.3, 7.65; HRMS (ESI+,
TFA-Na) calcd for C15H24NaO4 291.1572 [M+Na]+, found m/z 291.1576.
To a solution of the alcohol (38.1mg, 0.14mmol) in CH2Cl2 (5.0ml) was
added a solution of Grubbs second-generation catalyst (6.0mg, 0.01 mmol)
in CH2Cl2 (9.2ml) at rt under N2. The reaction mixture was stirred for 2 h at
40 1C. After the reaction was complete, Quadrasil AP (500 mg) was added to the
reaction mixture. The suspension was stirred for 5min at rt and then allowed to
stand for 10min. The mixture was filtered through a pad of celite and the filtrate
was washed with H2O. The organic layers were dried over anhydrous Na2SO4
and concentrated in vacuo. The residue was purified by flash column chroma-
tography (5:1 hexanes/EtOAc) to afford 1 (43.2 mg, quant.) as a colorless oil.
5
6
Takano, E. et al. Purification and structural determination of SCB1, a g-butyrolactone
that elicits antibiotic production in Streptomyces coelicolor A3 (2). J. Biol. Chem. 275,
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a novel Streptomyces hormone controlling antibiotic
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16415 (2011).
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Mukku, V. J. R., Speitling, M., Laatsch, H. & Helmke, E. New butenolides from two
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(1988).
9
10 Kolb, H., VanNiewenhze, M. S. & Sharpless, K. B. Catalytic asymmetric dihydroxyla-
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[a]D26 +2.27 (c 1.0 CHCl3); IR (KBr) 3480, 2929, 2858, 1746, 1710, 1459 cmꢂ1
;
1H-NMR (300 MHz, CDCl3) d 7.44 (dd, J¼5.8, 1.5 Hz, 1H), 6.11 (dd, J¼5.7,
2.0 Hz, 1H), 5.05–5.02 (m, 1H), 3.76 (brs, 1H), 2.56–2.47 (m, 2H), 1.83–1.61 (m,
6H), 1.61–1.42 (m, 2H), 1.33 (s, 3H), 0.79 (t, J¼7.4 Hz, 3H); 13C-NMR (75.0 MHz,
CDCl3) d 214.2, 173.0, 156.1, 121.7, 83.0, 78.9, 35.4, 33.0, 32.4, 25.2, 24.6, 23.2, 7.66;
HRMS (FAB, m-NBA) calcd for C13H21O4 241.1440 [M+H]+, found m/z 241.1447.
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dinone oxidation. Org. Lett. 11, 3152–3155 (2009).
(4S,10S)-avenolide (19). [a]D24+48.91 (c 1.0, CHCl3); IR (KBr) 3483, 2940, 2874,
1748, 1711, 1459 cmꢂ1
;
1H-NMR (300 MHz, CDCl3) d 7.45 (dd, J¼5.7, 1.5 Hz,
1H), 6.12 (dd, J¼5.7, 2.1 Hz, 1H), 5.08–5.03 (m, 1H), 3.77 (brs, 1H), 2.60–2.45 (m,
2H), 1.87–1.41 (m, 8H), 1.34 (s, 3H), 0.81 (t, J¼7.5 Hz, 3H); 13C-NMR (75.0 MHz,
CDCl3) d 214.1, 173.0, 156.0, 121.7, 83.0, 78.9, 35.4, 33.0, 32.4, 25.2, 24.6, 23.1, 7.66;
HRMS (FAB, m-NBA) calcd for C13H21O4 241.1440 [M+H]+, found m/z 241.1438.
16 Liu, J.- H., Song, L.- D.
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a
a
(4R,10R)-avenolide (22). [a]2D6 ꢂ51.07 (c 1.0. CHCl3); IR (KBr) 3482, 3093,
2930, 1748, 1458cmꢂ1; 1H-NMR (300MHz, CDCl3) d 7.45 (dd, J¼5.7, 1.5 Hz,
1H), 6.12 (dd, J¼5.7, 2.1 Hz, 1H), 5.07–5.02 (m, 1H), 3.76 (brs, 1H), 2.59–2.45
(m, 2H), 1.86–1.34 (m, 8H), 1.34 (s, 3H), 0.80 (t, J¼7.4 Hz, 3H); 13C-NMR
(75.0MHz, CDCl3) d 214.4, 173.2, 156.2, 121.9, 83.2, 79.1, 35.6, 33.2, 32.6,
35.4, 24.9, 23.3, 7.86; HRMS (ESI+, TFA-Na) calcd for C13H20NaO4 263.1259
[M+Na]+, found m/z 263.1271.
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10-Deoxy avenolide (28). [a]D25 +47.75 (c 1.0. CHCl3); IR (KBr) 3503, 3091,
2930, 1753, 1708cmꢂ1; 1H-NMR (300MHz, CDCl3) d 7.45 (dd, J¼5.7, 1.5 Hz,
1H), 6.11 (dd, J¼5.7, 2.1 Hz, 1H), 5.07–5.02 (m, 1H), 2.47–2.40 (m, 3H),
1.81–1.28 (m, 8H), 1.05 (d, J¼7.0Hz, 3H), 0.87 (t, J¼7.5 Hz, 3H); 13C-NMR
(75.0MHz, CDCl3) d 214.4, 173.1, 156.2, 121.6, 83.1, 47.9, 40.6, 33.1, 25.9,
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