Three- and Four-Carbon Elongating Ring Expansion of Cyclic Acetals to Medium-Sized Dioxacycloalkenones. Use of the Intramolecular Formation of Oxonium Ylides

Article abstract of DOI:10.1021/jo961844x

The Rh(II)-catalyzed reaction of 2-(3′-diazo-2′-oxopropyl)-2-methyldioxolane (1) in the presence of a protic nucleophile (NuH) such as AcOH resulted in effective ring enlargement to give the 8-membered 3-acetoxydioxocanone 4a (41%) and dioxocan-2-en-1-one 3 (46%). Similar treatment of 2-(4′-diazo-3′-oxobutyl)-2-methyldioxolane (9) with AcOH gave 4-acetoxydioxonanone 10 (67%), which was readily hydrolyzed on silica gel to a tautomeric mixture of hydrolysis products 16a and 16b (total yield 46%). In contrast, similar treatment of 2-(5′-diazo-4′-oxopentyl)-2-methyldioxolane (19) gave 2,5-dioxa-1-methyldecalin-7-one (20, 24%), and the yield increased to 61% in the absence of AcOH, by Stevens rearrangement. The reaction of 1,3-dioxane homologues 26 and 31 gave similar results. All of these reactions can be explained in terms of the intermediacy of bicyclooxonium ylides, which undergo either a Stevens rearrangement or, after protonation by a NuH, ring enlargement through release of the strain of the bicyclic ylides. Evidence of the reversible formation of oxonium ylides is also provided.

Full text of DOI:10.1021/jo961844x

J . Org. Chem. 1997, 62, 2123-2129
2123
Th r ee- a n d F ou r -Ca r bon Elon ga tin g Rin g Exp a n sion of Cyclic
Aceta ls to Med iu m -Sized Dioxa cycloa lk en on es. Use of th e
In tr a m olecu la r F or m a tion of Oxon iu m Ylid es
Akira Oku,* Nobuhito Murai, and J ulia Baird
Department of Chemistry and Materials Technology, Kyoto Institute of Technology,
Matsugasaki, Sakyo-ku, Kyoto 606, J apan
Received September 27, 1996X
The Rh(II)-catalyzed reaction of 2-(3′-diazo-2′-oxopropyl)-2-methyldioxolane (1) in the presence of
a protic nucleophile (NuH) such as AcOH resulted in effective ring enlargement to give the
8-membered 3-acetoxydioxocanone 4a (41%) and dioxocan-2-en-1-one 3 (46%). Similar treatment
of 2-(4′-diazo-3′-oxobutyl)-2-methyldioxolane (9) with AcOH gave 4-acetoxydioxonanone 10 (67%),
which was readily hydrolyzed on silica gel to a tautomeric mixture of hydrolysis products 16a and
16b (total yield 46%). In contrast, similar treatment of 2-(5′-diazo-4′-oxopentyl)-2-methyldioxolane
(19) gave 2,5-dioxa-1-methyldecalin-7-one (20, 24%), and the yield increased to 61% in the absence
of AcOH, by Stevens rearrangement. The reaction of 1,3-dioxane homologues 26 and 31 gave similar
results. All of these reactions can be explained in terms of the intermediacy of bicyclooxonium
ylides, which undergo either a Stevens rearrangement or, after protonation by a NuH, ring
enlargement through release of the strain of the bicyclic ylides. Evidence of the reversible formation
of oxonium ylides is also provided.
Sch em e 1
Ethereal oxonium ylides continue to elude spectro-
scopic identification.1 Nevertheless, their presence has
been frequently proposed and verified indirectly2 in
carbene reactions in which singlet carbenes are properly
generated in ethereal solvents or in the presence of
ethereal substrates.3 However, in comparison with car-
bonyl ylides, which have been extensively studied,4 the
use of ethereal ylides for synthetic purposes has been
limited. This lack is mainly due to the lability of the
ylides, which exist as extremely short-lived components
in equilibrium with the parent carbenes. In an effort to
further develop the synthetic utility of ethereal oxonium
ylides,5 we recently designed6 an intramolecular reaction
of carbenes with cyclic ethereal substituents to form
ethereal bicyclooxonium ylides, the kinetically formed
products, which is followed by release of the strain of the
constrained bicyclic intermediates to give open-ring
products. This ring-enlargement reaction may be of
synthetic interest (Scheme 1). We adopted three condi-
tions for this reaction: (1) use of medium-sized cyclic
ethers as intramolecular nucleophiles toward carbenes;
(2) diazo ketone side chains whose transition-metal
carbenoids can form entropically favorable, albeit short-
lived, 5- and 6-membered oxonium ylide intermediates,7
and ylide formation must be followed by fast, irreversible
reactions such as protonation or intramolecular proton
shift; and (3) the presence of ylide-stabilizing groups, such
as carbonyl groups. In this regard, Clark and his group8
have extensively studied other types of ring expansion,
i.e., (2,3)-sigmatropic rearrangement of vinyltetrahydro-
furanonium ylide systems,9 which are synthetically in-
teresting.
The limitation we encountered with diazocarbonyl-
substituted cyclic ether systems was the length of the
diazocarbonyl side chain:6 as the chain was elongated to
more than n ) 1, the desired ring enlargement did not
take place and a ring-switching reaction took place
instead. We presumed that if a cation-stabilizing group
was positioned adjacent to the bridgehead carbon of both
the ylides and oxonium ions, cleavage of the central bond
would be facilitated. The present study deals with cyclic
X Abstract published in Advance ACS Abstracts, March 15, 1997.
(1) (a) Padwa, A.; Hornbuckle, S. F. Chem. Rev. 1991, 91, 263. (b)
Tomioka, H.; Kobayashi, N.; Murata, S.; Ohtawa, T. J . Am. Chem. Soc.
1991, 113, 8771.
(2) (a) Kirmse, W.; Kapps, M. Chem. Ber. 1968, 994. (b) Ando, W.;
Kondo, S.; Nakayama, K.; Ichibori, K.; Kohoda, H.; Yamato, H.; Imai,
I.; Nakaido, S.; Migita, T. J . Am. Chem. Soc. 1972, 94, 3870. (c)
Friedrich, K.; J ansen, U.; Kirmse, W. Tetrahedron Lett. 1985, 26, 193.
(d) Kirmse, W.; Chiem. P. V. Ibid. 1985, 26, 197.
(3) (a) Iwamura, H.; Imahasi, Y. Tetrahedron Lett. 1975, 1401. (b)
Olah, G. A.; Doggweiler, H.; Felberg, J . D. J . Org. Chem. 1984, 49,
2116. (c) Baird, M. S.; Baxter, A. G. W.; Hoorter, A.; J efferson, I. J .
Chem. Soc., Perkin Trans. 1 1991, 2575. (d) West, F. G.; Eberlein, T.
H.; Tester, R. W. J . Org. Chem. 1992, 57, 3479. (e) Doyle, M. P.; Griffin,
J . H.; Chinn, M. S.; van Leusen, D. J . Org. Chem. 1984, 49, 1917. (f)
Pirrung, M. C.; Brown. W. L.; Rege, S.; Laughton, P. J . Am. Chem.
Soc. 1991, 113, 8561.
(7) (a) Hamaguchi, M.; Ibata, T. Tetrahedron Lett. 1974, 4475. (b)
Ibata, T.; Toyoda, J . Bull. Chem. Soc. J pn 1985, 58, 1787.
(8) For examples of the [2,3]-sigmatropic rearrangement of oxonium
ylides, see: (a) Clark, J . S.; Dossetter, A. G.; Whittingham, W. G.
Tetrahedron Lett. 1996, 37, 5603. (b) Clark, J . S.; Whitlock, G. A.
Tetrahedron Lett. 1994, 35, 6381.
(4) (a) Padwa, A.; Hornbuckle, S. F. Chem. Rev. 1991, 91, 263. (b)
Padwa, A.; Krumpe, K. E. Tetrahedron. 1992, 48, 5385.
(5) Oku, A. J . Synth. Org. Chem. J pn. 1995, 18.
(6) Oku, A.; Ohki, S.; Yoshida, T.; Kimura, K. J . Chem. Soc., Chem.
Commun. 1996, 1077.
(9) Pirrung, M. C.; Werner, J . A. J . Am. Chem. Soc. 1986, 108, 6060.
S0022-3263(96)01844-0 CCC: $14.00 © 1997 American Chemical Society

2124 J . Org. Chem., Vol. 62, No. 7, 1997
Oku et al.
Sch em e 2
Sch em e 3
acetal systems instead of cyclic ethers in the hope of
demonstrating the anticipated bond-cleaving effect
(Scheme 2).
Resu lts a n d Discu ssion
P r ep a r a tion of Dia zoca r bon yl-Su bstitu ted Cyclic
Aceta ls. Diazocarbonyl-substituted cyclic acetals 1, 9,
19, 26, and 31 were prepared from keto esters as reported
17-19
elsewhere (eq 1).10,
a protic nucleophile (NuH). Indeed, when the analogous
reaction was carried out in CH2Cl2 in the presence of
acetic acid, ring-enlargement products 3 and 4a were
formed in high yields (46 and 41%, respectively, overall
87%) (eq 3). Thus, acetic acid dramatically facilitated
the ring-enlargement process. This facilitation is as-
sumed to be due to (1) faster protonation of ylide 6 than
its rearrangement to 2 (Scheme 3) and (2) stabilization
of bicyclooxonium ylide 6 and its ring-opened monocyclic
zwitterion structure 6a by charge-delocalization in two-
oxygen systems and similar stabilization of protonated
oxonium ion 7 and its ring-opened structure 7a (Scheme
3). In this sense, the ring-opening of 7 should be
facilitated more than that of the related tetrahydrofura-
nonium system 8a .13
Rh (II)-Ca ta lyzed Rea ction of 2-(3′-Dia zo-2′-oxo-
p r op yl)-2-m eth yld ioxola n e (1) in th e P r esen ce of
Acetic Acid . Roskamp and J ohnson11 first reported that
the Rh-catalyzed reaction of 1 in benzene yielded bicyclo-
[4.2.0]-2,5-dioxaoctanone 2 (68%) together with a small
amount of 4,7-dioxocan-2-en-1-one (3, 16%) (eq 2).
A
Even a weak acid such as methanol can protonate ylide
6 before rearrangement occurs. Thus, when methanol
was used in place of acetic acid, a similar ring-enlarge-
ment reaction gave 4b (47%) but not 3. This indicates
that dioxolane ylide 6 is longer-lived than the tetrahy-
drofuran ylide 86 and can be protonated by methanol
whereas 8 cannot.
Rea ction of 2-(4′-Dia zo-3′-oxobu tyl)-2-m eth yld iox-
ola n e (9). On the basis of the anticipated facilitation of
the enlargement of two-oxygen systems, we expected that
the elongation of the diazocarbonyl side chain by a one-
methylene unit would also enable a similar reaction to
occur. Indeed, the analogous reaction of dioxolanyl diazo
ketone 9 in the presence of acetic acid produced ring-
enlargement product 10 (67%) in addition to nonrear-
rangement product 11 (6%) (eq 4).
similar 1,2-shift in oxonium ylides has been reported by
Brogan and co-workers.12 We thought that the ring-
enlarged 3 would become a major product if the formation
of Stevens rearrangement product 2 could be suppressed
by protonating the plausible bicyclooxonium ylide 6 with
(10) Thus, L.; Smeets, F. L. M.; Cillissen, P. J . M.; Harmsen, J .;
Zwanenburg, B. Tetrahedron. 1980, 36, 2141.
(11) Roskamp, E. J .; J ohnson, C. R. J . Am. Chem. Soc. 1986, 108,
6062.
(12) Brogan, J . B.; Bauer, C. B.; Rogers, R. D.; Zercher, C. K.
Tetrahedron Lett. 1996, 37, 5053.
(13) Kamada, T.; Ge-Quing, Abe, M.; Oku, A. J . Chem. Soc., Perkin
Trans. 1 1996, 413.

Intramolecular Formation of Oxonium Ylides
J . Org. Chem., Vol. 62, No. 7, 1997 2125
Sch em e 4
Sch em e 6
Sch em e 5
formed into a mixture of the endo- and exo-isomers of
cyclic enol ether 17 and 18.
In the presence of MeOH, the outcome of the reaction
of 9 was different from that of 1 (vide supra). The
nonrearrangement product 11a was obtained exclusively
instead of the expected ring-enlargement products. This
observation provides additional evidence concerning the
reversibility of oxonium ylide formation between keto-
carbenoids and ethereal oxygen atoms (eq 5).14,16 In the
In contrast to the reaction of 1, the formation of a small
amount of 11 from 9 implies that cyclization of the linear
carbenoid 12 to the 1,7-dioxabicyclo[4.3.0]nonanone-type
oxonium ylide 13 may not be as favorable as that of 5 to
6. Therefore, a minor amount of 12 that is formed either
directly from 9 or reversibly from the ylide14 could be
trapped by a protic nucleophile (NuH) to give 11 or 11a
(Scheme 4). Most of 12 underwent cyclization to form
ylide 13 and finally resulted in the formation of 10, which
is analogous to the result with 6. In a previous study in
which we postulated the formation of a 1-oxabicyclo[4.3.0]-
octanone-type oxonium ylide (A in Scheme 1, m ) 1, n )
2),6 the ylide did not undergo cleavage of the central
bridging bond, in contrast to the behavior of 13. This
difference can be attributed to the stabilizing effects of
the second acetal oxygen atoms in ylide 13 (or its
zwitterion 13a ) and oxonium ion 14 (or 14a ).
Acetoxydioxocanone 10 is labile under weakly acidic
conditions, such as in silica gel chromatography. For
example, under treatment with aqueous MeOH and even
on a silica gel TLC plate, 10 undergoes hydrolysis to give
an equilibrium mixture of 16a and its isomer 16b
(Scheme 5).15 The structure of 16a was determined by
1H-NMR after its transformation to the corresponding
silyl ether. Compound 10 is also thermally labile (e.g.,
under VPC analysis conditions) and is readily trans-
reaction of 9, MeOH traps the initially produced linear
carbenoid 12 in a nucleophilic manner and prevents its
cyclization. A strong acid but a weak nucleophile, such
as AcOH, waves the protonation of 12 to help its
cyclization. Our rationale for explaining this discrepancy
is shown in Scheme 6. When n ) 1, carbenoid B forms
the bicyclic ylide C, which, due to its strain energy,
prefers to exist as the monocyclic zwitterion structure D.
We presume that D can be protonated much faster than
C due to its charge separation, thereby enabling proto-
nation even using methanol. When n ) 2, the ylide may
prefer the less-strained and electronically more-stable
bicyclic form C to the monocyclic form D. The rate of
protonation of C may be slower than the rate of the
reversion back to carbenoid B. The subsequent formation
of products 10 and 11 can be explained in terms of these
intermediates.6
R ea ct ion of 2-(5′-Dia zo-4′-oxop en t yl)-2-m et h yl-
d ioxola n e (19). The reaction of 19, which has a longer
diazocarbonyl side chain than 1 by two methylene units,
in the presence of nucleophiles such as MeOH, AcOH,
p-NO2C6H4OH, and PhCOOH was also examined. Two
products identified as 5′-substituted 2-methyl-2-(4′-oxo-
pentyl)dioxolane 21 and 2,5-dioxa-1-methyldecahydronaph-
thalen-7-one (20) were formed. Decalone 20 was pro-
(14) (a) Naito, I.; Oku, A.; Otani, N.; Fujiwara, Y.; Tanimoto, Y. J .
Chem. Soc., Perkin Trans. 2 1996, 725. (b) West, F. G.; Eberlein, T.
H.; Tester, R. W. J . Chem. Soc., Perkin Trans. 1 1993, 2857.
(15) We identified 16a and 16b by silylation. The mixture of 16a
and 16b was treated with dimethyl-tert-butylsilyl chloride and imi-
dazole in dimethylformamide at room temperature for 18 h. 9-[(tert-
Butyldimethylsilyl)oxy]-7-oxanonane-2,5-dione was obtained in 46%
yield.
(16) Very recently, Sueda and Ochiai reported evidence of reversible
ylide formation between free alkylidenecarbenes and ethers. Sueda,
T.; Nagaoka, T.; Goto, S.; Ochiai, M. J . Am. Chem. Soc. 1996, 118,
10141-10149.

2126 J . Org. Chem., Vol. 62, No. 7, 1997
Oku et al.
Sch em e 7
of MeOH (instead of AcOH), 29 (47%) was the major
product in addition to the ring-enlargement products 30b
(X ) MeO, 4%) and 28b (6%). When MeOH was added
to the reaction mixture immediately after the reaction
with AcOH was complete, the yield of ring-enlargement
product 30b increased to 43% and compounds 28a (7%),
28b (4%), and 29 (6%) were also present (eq 8). These
findings indicate that protonation of the intermediate
ylide 27 or 27a is essential to suppress rearrangement
to 29 (Scheme 8).
duced by Stevens rearrangement (eq 6), and its yield
increased to 61% in the absence of a nucleophile.
The mechanisms for the formation of the two isomeric
products 28a and 28b appear to be different, on the basis
of the following observations: (1) eq 8 indicates that the
major product 30a is labile enough to react with MeOH,
and (2) in the absence of a NuH, enone 28b (10%) was
the only enlargement product besides rearrangement
product 29, indicating that 28b must be formed by an
intramolecular proton shift but not via intermediate 30.
This result also indicates that in the absence of a NuH
ylide 27 mostly undergoes Stevens rearrangement. There-
fore, the formation of 28a in the presence of AcOH may
follow a different route, such as via the elimination of
labile intermediate 30a (X ) AcO).
Rea ction of 2-(4′-Dia zo-3′-oxobu tyl)-2-m eth yl-1,3-
d ioxa n e (31). Elongation of the diazoalkyl side chain
of the dioxane series also disfavored the expected en-
largement reaction as with the dioxolane series 9 and
19. Thus, when 31 was treated under analogous condi-
tions in the presence of AcOH, 10-hydroxy-7-oxadecane-
2,5-dione 35 (25%) was obtained in addition to the
Stevens rearrangement product 33 (12%) and the non-
rearranged product 34 (10%) (eq 9). The expected ring-
enlargement product 36a was not obtained. When
MeOH was used in place of AcOH, ring-enlargement
product 36b (X ) OMe) (10%) was obtained in addition
to 34 (34%); when a mixture of AcOH and MeOH was
used, 36b (12%), 35 (13%), 33 (7%), 34 (7%), and its MeO-
derivative (15%) were obtained. In the absence of nu-
cleophiles, 33 was the only product isolated. Although
ring-enlargement products were not isolated with AcOH,
35 was evidently formed from the ring-enlargement
intermediate 36a , which in turn was derived from 32a
(Scheme 9).
Although the anticipated ring-enlargement product 24
was not obtained, the formation of 20 as the major
product unequivocally supports the intermediacy of
bicyclo[5.3.0]dioxadecanone-type oxonium ylide 23 as the
key intermediate that possesses a less-strained bicyclo-
[5.3.0] structure (Scheme 7). As noted in Scheme 6, ylide
23 () C, n ) 3) may prefer a less strained and more
stable bicyclic structure to zwitterion structure 25 and,
therefore, undergoes a rapid Stevens rearrangement to
the less-strained decalone 20 much faster than protona-
tion by a strong acid such as benzoic acid. The reversible
interconversion of 23 to 22 is also possible, and the
formation of 21 from 22 seems to be dependent on the
nucleophilicity of the NuH rather than the acidity.
Rea ction of 2-(3′-d ia zo-2′-oxop r op yl)-2-m eth yl-1,3-
d ioxa n e (26). An important factor in ylide formation
is the nucleophilicity of the acetal oxygen atom. In
general, the nucleophilicity of cyclic ethers varies in the
order THF > THP > Et2O, and we assume a similar order
of nucleophilicity with cyclic acetals in that 1,3-dioxane
will be next to 1,3-dioxolane. In addition, adoption of a
1,3-dioxane ring rather than a dioxolane ring will enable
a larger ring-expansion reaction, thereby extending the
synthetic utility of the reaction. In this regard, the
analogous reaction of the dioxane-substituted diazo
ketone 26 in the presence of acetic acid was examined,
and we found that an isomeric mixture of ring-enlarge-
ment products 28a (cis) and 28b(trans) (overall 55%) was
formed in addition to the Stevens rearrangement product
29 (6%) (eq 7). In the absence of AcOH, the amount of
enlargement product 28b decreased to 10% (28a was not
formed), whereas 29 increased to 50%. In the presence
The rearrangement product 33 was labile under acidic
conditions and quantitatively gave the ring-opened cy-
clopentenone 37 (eq 10).
Con clu sion s
The expected ring-enlargement reaction (Scheme 2)
was realized in four of the systems examined (1, 9, 26,

Intramolecular Formation of Oxonium Ylides
J . Org. Chem., Vol. 62, No. 7, 1997 2127
Sch em e 8
benoids can be classified into two types according to the
length of the side chain, i.e., (a) n ) 1 for 1 and 26 and
(b) n ) 2 (or 3) for 9, 19, and 31. Thus, with 1 or 26 (n
) 1), strained bicyclic ylide C is formed faster than with
n ) 2, and this undergoes ring opening to zwitterion D
faster than the reversible reaction, due to strain release,
and D is protonated by MeOH. With 9 or 31 (n ) 2), a
less-strained bicyclic ylide is formed more slowly than
with n ) 1 and, therefore, the open-chain carbenoids B
are trapped by the strong nucleophile MeOH before
cyclization. In addition, even after C is formed, a
reversible reaction from C to B occurs in competition with
other reactions, which are slower than those with n ) 1
due to the lower strain of C, and B is trapped by MeOH.
However, the effect of ring-size (dioxolane vs dioxane) on
the reversible process between open-chain carbenoid (e.g.,
B) and bicyclic ylide (e.g., C) is not as significant as the
side-chain effect.
Sch em e 9
Using the present method, similar ring-enlargement
reactions may be possible with other diazoalkyl-substi-
tuted cyclic acetals with rings larger than 1,3-dioxane,
such as dioxepanes and dioxocanes, and several medium-
sized dioxacycloalkanone derivatives may become avail-
able through the generation of bicyclo[n.3.0]- and [n.4.0]-
oxonium ylide intermediates (n > 3).
and 31) but was unsuccessful with substrate 19. The
formation of strained bicyclooxonium ylide intermediates
(e.g., C in Scheme 6) and the stability of both the ylides
and their ring-opened monocyclic zwitterion (e.g., D in
Scheme 6) seem to be the dominant factors in facilitating
the ring-enlargement reaction. The presence of the
second oxygen atom in the acetal ring evidently stabilizes
the zwitterion structure sufficiently to enable enlarge-
ment of the bicyclo[3.4.0]- and [4.4.0]-ylide systems 13
and 32, but not that of the corresponding tetrahydro-
furanyl (15) and tetrahydropyranyl systems.6
To summarize, when AcOH is adopted as a nucleophile
and acid, the product ratios can be adequately explained
by the equilibrium between B and C for open chain vs
other products and between C and D for Stevens rear-
rangement products vs ring-enlargement products (Scheme
6 and also Schemes 3, 4, and 7-9). When one adopts
MeOH, which is a weaker acid and a stronger nucleophile
than AcOH, the reaction behavior of the rhodium car-
Exp er im en ta l Section
Gen er a l Meth od s. 1H and 13C NMR spectra were ex-
pressed in ppm (δ) using residual CHCl3 (δ 7.26) and CDCl3
(δ 77.00) as the internal standard. Flash column chromatog-
raphy was performed using silica gel (Wakogel C-300) or
alumina (Merck aluminum oxide 90 active basic). Solvents
were dried and distilled before use. Dirhodium tetraacetate
was dried in vacuo before use. HRMS analyses were per-
formed on most of the key products (liquid) instead of
elemental analyses.
P r ep a r a tion of Dia zo Keton es. Diazo ketones 1 and 26
were prepared from ethyl acetoacetate, 9 and 31 from ethyl
4-oxo pentanoate, and 19 from ethyl 5-oxohexanoate according
to eq 1 by utilizing conventional methods: i.e., acetalization,17
alkaline hydrolysis,18 methoxycarbonylation,19 and diazom-
(17) Daignault, R. A.; Eliel, E. L. Organic Syntheses 1973, Col. Vol.
5, 303.
(18) (a) J ohnson, J . R.; Hanger, F. D. Org. Synth. 1941, Col. Vol. 1,
351. (b) Warren, C. K.; Weedon, B. C. L. J . Chem. Soc. 1958, 3972.

2128 J . Org. Chem., Vol. 62, No. 7, 1997
Oku et al.
ethylation.19 Overall yields of diazo ketones from the corre-
sponding starting esters were 1 (44%), 9 (52%), 19 (54%), 26
(48%), and 31 (41%).
NuH (0.706 mmol, 1.3 equiv) and diazo ketone (0.50 mmol)
dissolved in CH2Cl2 (3.0 mL) at one time under an argon
atmosphere at ambient temperature. The reaction mixture
was stirred for 30 min, in general, until the diazo ketone was
not detectable on a TLC plate. After workup with 8 mL of
saturated aqueous NaHCO3 solution, the solvent was removed
and the residue was chromatographed through a flash column,
in general, on silica gel or basic alumina in the cases where
certain products 4a , 10, 30a , 33, and 36a were proved labile
on silica gel. Some products (17 and 18) were isolated by
distillation under vacuum.
Spectroscopic data of diazo ketones and the corresponding
precursors are as follows.
2-[(E t h oxyca r b on yl)m et h yl)-2-m et h yld ioxola n e: 1H
NMR (300 MHz, CDCl3) 1.19 (t, J ) 7.2 Hz, 3H), 1.42 (s, 3H),
2.59 (s, 2H), 3.90 (s, 4H), 4.07 (q, J ) 7.2 Hz, 2H); IR (liquid
film) 1740 (s) cm-1. 2-(Ca r boxym eth yl) a n a logu e: 1H NMR
(300 MHz, CDCl3) 1.48 (s, 3H), 2.69 (s, 2H), 3.97 (s, 4H), 10.15
(brs, 1H); IR (liquid film) 2400-3400 (br), 1720 (s) cm-1
.
2-(3′-Diazo-2′-oxopr opyl)-2-m eth yldioxolan e (1): 1H NMR
(300 MHz, CDCl3) 1.39 (s, 3H), 2.63 (s, 2H), 3.94-3.97 (m, 4H),
5.46 (s, 1H); 13C NMR (75.6 MHz, CDCl3) 24.2, 50.5, 55.6, 64.6,
Spectroscopic data of the products are as follows.
3-Meth yl-4,7-d ioxoca n -2-en -1-on e (3):11 1H NMR (300
MHz, CDCl3) 1.98 (s, 3H), 3.94-3.98 (m, 2H), 4.05 (s, 2H),
4.14-4.17 (m, 2H), 5.01 (s, 1H); 13C NMR (75.6 MHz, CDCl3)
23.4, 67.6, 72.2, 74.7, 100.9, 168.7, 201.3; IR (liquid film) 1740
(s), 1620 (s) cm-1; HRMS (EI) calcd for C7H10O3 (M+) 142.0629,
found 142.0633.
107.8, 190.8; IR (liquid film) 2100 (s), 1640 (s) cm-1
.
2-[2′-(E t h oxyca r b on yl)et h yl]-2-m et h yld ioxola n e: 1H
NMR (300 MHz, CDCl3) 1.24 (t, J ) 7.2 Hz, 3H), 1.31 (s, 3H),
2.00 (d, J ) 7.5 Hz, 1H), 2.02 (d, J ) 7.8 Hz, 1H), 2.36 (d, J )
7.8 Hz, 1H), 2.40 (d, J ) 7.5Hz, 1H) 3.90-3.95 (m, 4H), 4.12
(q, J ) 7.2 Hz, 2H); IR (liquid film) 1740 (s) cm-1. 2′-Ca r boxy
a n a logu e: 1H NMR (300 MHz, CDCl3) 1.33 (s, 3H), 2.03 (d, J
) 7.2 Hz, 1H), 2.05 (d, J ) 7.8 Hz, 1H), 2.43 (d, J ) 7.8 Hz,
1H), 2.45 (d, J ) 7.2, 1H), 3.90-4.00 (m, 4H), 10.58 (brs, 1H);
7-Acet oxy-7-m et h yl-3,6-d ioxoca n -1-on e (4a ): 1H NMR
(300 MHz, CDCl3) 1.70 (s, 3H), 2.06 (s, 3H), 3.01 (d, J ) 11.4
Hz, 1H), 3.58-3.72 (m, 3H), 3.84 (d, J ) 18.3 Hz, 1H), 4.15 (d,
J ) 18.3 Hz, 1H), 4.22-4.31 (m, 1H); 13C NMR (75.6 MHz,
CDCl3) 22.0, 24.4, 45.9, 64.3, 73.4, 78.5, 104.3, 168.9, 211.0;
IR (liquid film) 2400-3400 (br), 1720 (s) cm-1
.
IR (liquid film) 1740 (s), 1720 (s) cm-1
.
2-(4′-Dia zo-3′-oxobu tyl)-2-m eth yld ioxola n e (9): 1H NMR
(300 MHz, CDCl3) 1.32 (s, 3H), 1.99-2.04 (m, 2H), 2.40-2.44
(m, 2H), 3.89-3.99 (m, 4H), 5.24 (brs, 1H); 13C NMR (75.6
MHz, CDCl3) 23.6, 33.4, 35.0, 54.1, 64.4, 108.9, 194.4; IR (liquid
7-Meth oxy a n a logu e 4b: 1H NMR (300 MHz, CDCl3) 1.34
(d, J ) 0.9 Hz, 3H), 2.38 (d, J ) 11.1 Hz, 1H), 3.21 (s, 3H),
3.46-3.62 (m, 2H), 3.60 (d, J ) 11.1 Hz, 1H), 3.81 (dd, J )
0.3, 18.3 Hz, 1H), 3.93-3.99 (m, 1H), 4.17 (d, J ) 18.3 Hz,
1H), 4.24-4.29 (m, 1H); 13C NMR (75.6 MHz, CDCl3) 21.9,
47.7, 48.4, 62.4, 73.8, 78.9, 100.2, 212.2; IR (liquid film) 1750
(s), 1380 (s), 1220 (s), 1170 (s) cm-1; HRMS (EI) calcd for
C8H14O4 (M+) 174.0891, found 174.0900.
film) 2100 (s), 1640 (s) (m) cm-1
.
1
2-[3′-(Eth oxyca r bon yl)p r op yl]-2-m eth yld ioxola n e: H
NMR (300 MHz, CDCl3) 1.22 (t, J ) 7.2 Hz, 3H), 1.29 (s, 3H),
1.60-1.76 (m, 4H), 2.29 (t, J ) 7.2 Hz, 2H), 3.85-3.95 (m, 4H),
4.09 (q, J ) 7.2 Hz, 2H); IR (liquid film) 1740 (s) cm-1
. 3′-
7-Acetoxy-7-m eth yl-3,6-d ioxon a n -1-on e (10): 1H NMR
(300 MHz, CDCl3) 1.72 (s, 3H), 2.02 (s, 3H), 2.29-2.34 (m, 1H),
2.44-2.47 (m, 1H), 2.63 (d, J ) 10.8 Hz, 1H), 2.70 (d, J ) 10.8
Hz, 1H), 3.64-3.75 (m, 4H), 4.00 (d, J ) 15.6 Hz, 1H), 4.11 (d,
J ) 15.6 Hz, 1H); 13C NMR (75.6 MHz, CDCl3) 22.1, 22.3, 34.7,
34.9, 64.1, 72.9, 81.6, 106.7, 169.3, 210.7; IR (liquid film) 1730
ca r boxy a n a logu e: 1H NMR (300 MHz, CDCl3) 1.32 (s, 3H),
1.66-1.79 (m, 4H), 2.36-2.40 (m, 2H), 3.88-3.98 (m, 4H); IR
(liquid film) 2400-3700 (br), 1710 (s) cm-1
.
2-(5′-Dia zo-4′-oxop en tyl)-2-m eth yld ioxola n e (19): 1H
NMR (300 MHz, CDCl3) 1.30 (s, 3H), 1.62-1.77 (m, 4H), 2.35-
2.39 (m, 2H), 3.89-3.94 (m, 4H), 5.24 (brs, 1H); 13C NMR (75.6
MHz, CDCl3) 19.6, 23.7, 38.2, 40.7, 54.3, 64.6, 109.7, 194.8;
(s), 1720 (s) cm-1
.
1
2-(4′-Acetoxy-3′-oxobu tyl)-2-m eth yld ioxola n e (11): H
NMR (300 MHz, CDCl3) 1.31 (s, 3H), 2.00 (d, J ) 7.2 Hz, 1H),
2.03 (d, J ) 7.5 Hz, 1H), 2.16 (s, 3H), 2.47 (d, J ) 7.5 Hz, 1H)
2.49 (d, J ) 7.2 Hz, 1H), 3.86-3.97 (m, 4H), 4.67 (s, 2H); 13C
NMR (75.6 MHz, CDCl3) 20.5, 23.9, 32.4, 33.4, 64.7, 67.9,
IR (liquid film) 2100 (s), 1640 (s) cm-1
.
2-[(Eth oxyca r bon yl)m eth yl]-2-m eth yl-1,3-d ioxa n e: 1H
NMR (300 MHz, CDCl3) 1.23 (t, J ) 7.2 Hz 3H), 1.52 (s, 3H),
1.63-1.73 (m, 2H), 2.77 (s, 2H), 3.84-3.97 (m, 4H), 4.12 (q, J
) 7.2 Hz, 2H); IR (liquid film) 1740 (s) cm-1
. 2-Ca r b oxy
109.0, 170.3, 203.4; IR (liquid film) 1750 (s), 1725 (s) cm-1
;
a n a logu e: 1H NMR (300 MHz, CDCl3) 1.56 (s, 3H), 1.56-1.66,
(m, 1H), 1.84-1.98, (m, 1H), 2.78 (s, 2H), 3.91-4.06 (m, 4H);
HRMS (CI) calcd for C10H17O5 (MH+) 217.1075, found 217.1065.
1
4′-Meth oxy a n a logu e (11a ): H NMR (300 MHz, CDCl3)
IR (liquid film) 2400-3700 (br), 1720 (s) cm-1
.
1.32 (s, 3H), 2.01 (t, J ) 7.2 Hz, 4H), 2.51 (t, J ) 7.2 Hz, 2H),
3.41 (s, 3H), 3.90-3.95 (m, 4H), 4.03 (s, 2H); 13C NMR (75.6
MHz, CDCl3) 23.7, 32.2, 33.2, 59.1, 64.5, 77.3, 109.0, 208.0;
IR (liquid film) 1720 (s) cm-1; HRMS (CI) calcd for C9H17O4
(MH+) 189.1126, found 189.1119.
(ter t-Bu tyld im eth ylsilyl)oxy d Er iva tive of 9-Hyd r oxy-
7-oxa n on a n e-2,5-d ion e (16a ). Because 16a and 16b were
not isolable in a pure state, an anomeric mixture of 16a and
16b was treated with tert-butyldimethylchlorosilane to be
converted to the corresponding silyloxy derivative and ana-
lyzed: 1H NMR (300 MHz, CDCl3) 0.06 (s, 6H), 0.88 (s, 9H),
2.17(s, 3H), 2.68-2.77 (m, 4H), 3.58 (d, J ) 5.7 Hz, 1H), 3.59
(d, J ) 5.1 Hz, 1H), 3.77 (d, J ) 5.1 Hz, 1H), 3.79 (d, J ) 5.7
Hz, 1H), 4.15 (s, 2H); 13C NMR (75.6 MHz, CDCl3) -5.4, 18.3,
25.8, 29.8, 32.4, 36.5, 62.7, 73.1, 76.5, 206.8, 208.0; IR (liquid
film) 1720 (s) cm-1; HRMS (CI) calcd for C14H29O4Si (MH+)
289.1834, found 289.1834.
2-(3′-Dia zo-2′-oxop r op yl)-2-m eth yl-1,3-d ioxa n e (26): 1H
NMR (300 MHz, CDCl3) 1.50 (s, 3H), 1.50-1.58 (m, 1H), 1.81-
1.92 (m, 1H), 2.70 (s, 2H), 3.84-4.01 (m, 4H), 5.53 (bs, 1H);
13C NMR (75.6 MHz, CDCl3) 20.3, 25.2, 50.7, 55.3, 59.6, 97.8,
190.6; IR (liquid film) 2100 (s), 1640 (s) cm-1
.
2-[2′-(Eth oxyca r bon yl)eth yl]-2-m eth yl-1,3-d ioxa n e: 1H
NMR (300 MHz, CDCl3) 1.25 (t, J ) 7.2 Hz, 3H), 1.39 (s, 3H),
1.50-1.60 (m, 1H), 1.71-1.84 (m, 1H), 2.00-2.06 (m, 2H),
2.41-2.46 (m, 2H), 3.81-3.96 (m, 4H), 4.11 (q, J ) 7.2 Hz,
2H); IR (liquid film) 1735 (s) cm-1
. 2′-Ca r boxy a n a logu e:
1H NMR (300 MHz, CDCl3) 1.43 (s, 3H), 1.47-1.56 (m, 1H),
1.79-1.91 (m, 1H), 2.00 (d, J ) 7.2 Hz, 1H), 2.03 (d, J ) 7.5
Hz, 1H), 2.53, (dd, J ) 4.5, 7.5 Hz, 1H), 2.56 (dd, J ) 4.5, 7.2
Hz, 1H), 3.83-4.01 (m, 4H); IR (liquid film) 2400-3700 (br),
1720 (s) cm-1
.
2-(4′-Dia zo-3′-oxobu tyl)-2-m eth yl-1,3-d ioxa n e (31): 1H
NMR (300 MHz, CDCl3) 1.32 (d, J ) 3.0 Hz, 3H), 1.45-1.52
(m, 1H), 1.62-1.78 (m, 1H), 1.93 (dd, J ) 3.0, 8.0 Hz, 1H),
1.96 (dd, J ) 3.0, 8.0 Hz, 1H), 2.39 (br, 2H), 3.73-3.90 (m,
4H), 5.23 (brs, 1H); 13C NMR (75.6 MHz, CDCl3) 20.6, 25.3,
33.5, 34.8, 54.2, 59.7, 98.3, 195.0; IR (liquid film) 2100 (s), 1640
4-Meth ylen e-5,8-dioxon an -1-on e (18): 1H NMR (300 MHz,
C6D6) 2.15-2.19 (m, 2H), 2.32-2.36 (m, 2H), 3.12 (t, J ) 4.2
Hz, 2H), 3.45 (t, J ) 4.2 Hz, 2H), 3.70 (s, 2H), 3.81 (d, J ) 1.5
Hz, 1H), 4.00 (d, J ) 0.6 Hz, 1H); 1H NMR (300 MHz, in CDCl3)
2.50-2.60 (m, 4H), 3.75 (d, J ) 4.5 Hz 1H), 3.77 (d, J ) 3.6
Hz, 1H), 4.03 (d, J ) 3.6 Hz, 1H), 4.03 (s, 2H), 4.05 (d, J ) 4.5
(s) cm-1
.
Hz, 1H), 4.08 (d, J ) 1.8Hz, 1H), 4.26 (d, J ) 1.8 Hz, 1H); 13
C
Gen er a l P r oced u r e of Rh 2(OAc)4-Ca ta lyzed Rea ction
of Dia zo Keton es. To a CH2Cl2 solution (10 mL) of Rh2(OAc)4
(2.2 mg, 1.0 mol % equivalent) were added a protic nucleophile
NMR (75.6 MHz, CDCl3) 33.2, 35.0, 71.9, 73.0, 81.9, 89.3,
164.1, 210.7; IR (liquid film) 1730 (s), 1710 (s), 1645 (m) cm-1
.
HRMS (EI) calcd for C8H12O3 (M+) 156.0786, found 156.0794.
Another isomer 17 was unstable under chromatographic
conditions and, therefore, unable to be isolated. However,
(19) Padwa, A.; Fryxell, G. E.; Zhi, L. J . Am. Chem. Soc. 1990, 112,
3100.

Intramolecular Formation of Oxonium Ylides
J . Org. Chem., Vol. 62, No. 7, 1997 2129
their 1H NMR (300 MHz, CDCl3) were assigned as follows:
1.76 (d, J ) 1.2 Hz, 3H), 3.31 (dd, J ) 1.2 and 7.2 Hz, 2H),
3.65-3.68 (m, 2H), 3.90-3.94 (m, 2H), 3.97 (s, 2H), 4.88 (td, J
) 1.2 and 7.2 Hz, 1H).
Hz, 1H), 3.78 (d, J ) 12.3 Hz, 1H), 3.90 (ddd, J ) 1.8, 5.4,
10.2 Hz, 1H), 3.99 (d, J ) 16.2 Hz, 1H), 4.15 (td, J ) 4.2, 11.4
Hz, 1H); 13C NMR (75.6 MHz, CDCl3) 21.6, 28.3, 44.7, 48.5,
56.6, 67.4, 78.9, 101.2, 210.4; IR (liquid film) 1710 (s) cm-1
;
1-Meth yl-2,5-dioxadecah ydr on aph th alen -7-on e (20): 1H
NMR (300 MHz, CDCl3) 1.44 (s, 3H), 1.63-1.75 (m, 2H), 1.93-
2.08 (m, 1H), 2.14-2.29 (m, 2H), 2.51-2.58 (m, 1H), 3.46-
3.72 (m, 2H), 3.77 (s, 1H), 3.90-4.00 (m, 2H); 13C NMR (75.6
MHz, CDCl3) 20.0, 22.6, 35.6, 40.1, 60.3, 62.2, 82.7, 207.4; IR
(liquid film) 1720 (s) cm-1; HRMS (EI) calcd for C9H14O3 (M+)
170.0942, found 170.0938. Anal. Calcd for C9H14O3: C, 63.51,
H, 8.29. Found: C, 63.23, H, 8.43.
HRMS (EI) calcd for C9H16O4 (M+) 188.1048, found 188.1046.
1-Meth yl-2,6-d ioxa bicyclo[5.3.0]d eca n -8-on e (33): 1H
NMR (300 MHz, CDCl3) 1.43 (s, 3H), 1.82-1.99 (m, 3H), 2.07-
2.28 (m, 2H), 2.38-2.51 (m, 1H), 3.66-3.85 (m, 3H), 3.83 (s,
1H), 3.99-4.06 (m, 1H); 13C NMR (75.6 MHz, CDCl3) 20.8,
33.0, 33.1, 33.5, 62.3, 66.5, 81.2, 88.3, 214.2; IR (liquid film)
1750 (s) cm-1; HRMS (EI) calcd for C9H14O3 (M+) 170.0943,
found 170.0950.
2-(5′-Acetoxy-4′-oxop en tyl)-2-m eth yld ioxola n e (21, Nu
) AcO): H NMR (300 MHz, CDCl3) 1.30 (s, 3H), 1.61-1.78
2-(4′-Acetoxy-3′-oxobu tyl)-2-m eth yl-1,3-d ioxa n e (34): 1H
NMR (300 MHz, CDCl3) 1.39 (s, 3H), 1.45-1.52 (m, 1H), 1.76-
1.92 (m, 1H), 2.00 (t, J ) 7.2 Hz, 2H), 2.16 (s, 3H), 2.54 (t, J
) 7.2 Hz, 2H), 3.77-3.97 (m, 4H); 13C NMR (75.6 MHz, CDCl3)
19.8, 25.4, 32.6, 33.2, 59.7, 68.0, 76.5, 98.1, 170.2, 203.8; IR
(liquid film) 1750 (s), 1730 (s) cm-1; HRMS (EI) calcd for
C10H15O5 (M+ - CH3) 215.0919, found 215.0922.
1
(m, 4H), 2.16 (s, 3H), 2.44 (t, J ) 6.9 Hz, 2H), 3.89-3.94 (m,
4H), 4.64 (s, 2H); 13C NMR (75.6 MHz, CDCl3) 17.7, 20.4, 23.6,
38.0, 38.5, 64.5, 67.9, 109.6, 170.1, 203.5; IR (liquid film) 1750
(s), 1725 (s) cm-1; HRMS (EI) calcd for C10H15O5 (M+ - CH3)
215.0919, found 215.0915.
1
1
5′-Meth oxy a n a logu e of 21 (Nu ) MeO): H NMR (300
4′-Meth oxy a n a logu e of 34: H NMR (300 MHz, CDCl3)
MHz, CDCl3) 1.29 (s, 3H), 1.59-1.75 (m, 4H), 2.43 (d, J ) 6.9
Hz, 1H), 2.46 (d, J ) 6.9 Hz, 1H), 3.39 (s, 3H), 3.89-3.94 (m,
4H), 3.99 (s, 2H); 13C NMR (75.6 MHz, CDCl3) 17.9, 23.5, 38.3,
38.6, 59.1, 64.4, 77.7, 109.0, 208.1; IR (liquid film) 1720 (s)
cm-1; HRMS (EI) calcd for C10H19O4 (M+) 203.1282, found
203.1289.
1.39 (d, J ) 0.9 Hz, 3H), 1.48-1.56 (m, 1H), 1.72-1.86 (m,
1H), 1.98 (d, J ) 7.5 Hz, 1H), 2.01 (d, J ) 7.2 Hz, 1H), 2.54 (d,
J ) 7.2 Hz, 1H), 2.56 (d, J ) 7.5 Hz, 1H), 3.41 (d, J ) 0.9 Hz,
1H), 3.79-3.96 (m, 4H), 4.04 (s, 2H); 13C NMR (75.6 MHz,
CDCl3) 20.5, 25.4, 32.6, 32.8, 59.3, 59.7, 77.6, 98.3, 208.4; IR
(liquid film) 1720 (s) cm-1; HRMS (CI) calcd for C10H19O4
(MH+) 203.1283, found 203.1273.
1
5′-Ben zoyloxy a n a logu e of 21 (Nu ) P h CO2): H NMR
1
(300 MHz, CDCl3) 1.31 (s, 3H), 1.64-1.82 (m, 4H), 2.54 (t, J
) 7.2 Hz, 2H), 3.90-3.95 (m, 4H), 4.88 (s, 2H), 7.43-7.49 (m,
2H), 7.56-7.62 (m, 1H), 8.07-8.11 (m, 2H); 13C NMR (75.6
MHz, CDCl3) 17.7, 23.7, 38.0, 38.6, 64.6, 68.4, 109.7, 128.4,
129.8, 130.1, 133.4, 165.8, 203.8; IR (liquid film) 3060 (w), 1730
(s), 1720 (s) cm-1; HRMS (EI) calcd for C16H20O5 (M+ - CH3)
277.1075, found 277.1083.
10-Hyd r oxy-7-oxa d eca n e-2,5-d ion e (35): H NMR (300
MHz, CDCl3) 1.84 (m, J ) 5.7 Hz, 2H), 2.18 (s, 3H), 2.62 (d, J
) 7.8 Hz, 1H), 2.63 (d, J ) 6.6 Hz, 1H), 2.77 (d, J ) 6.6 Hz,
1H), 2.79 (d, J ) 7.8 Hz, 1H), 3.65 (t, J ) 5.7 Hz, 2H), 3.80 (t,
J ) 5.7 Hz, 2H), 4.17 (s, 2H); 13C NMR (75.6 MHz, CDCl3)
29.7, 32.0, 32.1, 36.7, 60.5, 69.6, 75.7, 206.9, 207.8; IR (liquid
film) 3700-3050 (br), 1720 (s), 1700 (s) cm-1; HRMS (EI) calcd
for C9H16O4 (M+) 188.1049, found 188.1046.
5′-p-Nitr oph en oxy an alogu e of 21 (Nu ) p-NO2C6H4CO2):
1H NMR (300 MHz, CDCl3) 1.31 (s, 3H), 1.63-1.81 (m, 4H),
2.60 (d, J ) 6.9 Hz, 1H), 2.62 (d, J ) 7.2 Hz, 1H), 3.89-3.95
(m, 4H), 4.67 (s, 2H), 6.94 (dd, J ) 5.7, 10.5 Hz, 1H), 6.94 (d,
J ) 9.0 Hz, 2H), 8.21 (dd, J ) 5.7, 10.5 Hz, 1H), 8.21 (d, J )
9.0 Hz, 1H); 13C NMR (75.6 MHz, CDCl3) 17.6, 23.6, 38.0, 38.8,
64.5, 72.7, 109.7, 114.6, 125.9, 142.2, 162.6, 204.9; IR (KBr)
3080 (m), 1730 (s), 1690 (s) cm-1; HRMS (CI) calcd for
C15H19O6N (MH+) 310.1289, found 310.1299.
8-Meth oxy-8-m eth yl-3,7-d ioxeca n -1-on e (36b): 1H NMR
(300 MHz, CDCl3) 1.34 (d, J ) 0.6 Hz, 3H), 1.68 (dd, J ) 5.4,
13.8 Hz, 1H), 1.71 (dd, J ) 5.7, 13.8 Hz, 1H), 1.76-1.83 (m,
1H), 2.24-2.33 (m, 1H), 2.41-2.50 (m, 1H), 2.61-2.69 (m, 1H),
3.23 (s, 3H), 3.45-3.51 (m, 1H), 3.70-3.77 (m, 2H), 3.84-3.92
(m, 1H), 3.94 (d, J ) 16.8 Hz, 1H), 4.07 (d, J ) 16.8 Hz, 1H);
13C NMR (75.6 MHz, CDCl3) 20.8, 29.3, 32.5, 35.3, 48.9, 59.0,
70.1, 76.4, 101.8, 211.6; IR (liquid film) 1710 (s) cm-1; HRMS
(EI) calcd for C10H18O4 (M+) 202.1205, found 202.1201.
2-[(3′-Hyd r oxyp r op yl)oxy]-3-m et h ylcyclop en t -2-en -1-
on e (37): 1H NMR (300 MHz, CDCl3) 1.87 (quint, J ) 5.7 Hz,
2H), 2.00 (s, 3H), 2.36-2.39 (m, 2H), 2.43-2.46 (m, 2H), 3.19
(Z)-3-Meth yl-4,8-d ioxon a n -2-en -1-on e (28a ): 1H NMR
(300 MHz, CDCl3) 1.87 (quint, J ) 5.7 Hz, 2H), 2.08 (s, 3H),
3.67 (t, J ) 5.7 Hz, 2H), 3.80 (t, J ) 5.7 Hz, 2H), 4.05 (s, 2H),
5.72 (s, 1H); 13C NMR (75.6 MHz, CDCl3) 24.3, 32.1, 60.6, 69.8,
72.1, 97.1, 190.0, 192.4; IR (liquid film) 1730 (s), 1600 (s) cm-1
;
(brs, 1H), 3.81 (t, J ) 5.7 Hz, 2H), 4.14 (t, J ) 5.7 Hz, 2H); 13
C
HRMS (CI) calcd for C8H13O3 (MH+) 157.0864, found 157.0857.
(E)-Isom er 28b: 1H NMR (300 MHz, CDCl3) 1.92 (quint, J
) 5.4 Hz, 2H), 1.99 (d, J ) 0.9 Hz, 3H), 3.88 (t, J ) 5.4 Hz,
2H), 4.19 (t, J ) 5.4 Hz, 2H), 4.25 (s, 3H), 5.20 (s, 1H); 13C
NMR (75.6 MHz, CDCl3) 18.0, 30.1, 68.5, 72.4, 78.7, 111.8,
166.4, 201.5; IR (liquid film) 1710 (m), 1640 (s) cm-1; HRMS
(CI) calcd for C8H13O3 (MH+) 157.0864, found 157.0859.
1-Meth yl-2,6-d ioxa bicyclo[5.2.0]n on a n -8-on e (29): 1H
NMR (300 MHz, CDCl3) 1.67 (s, 3H), 1.86-2.11 (m, 2H), 2.80
(dd, J ) 4.2, 18.0 Hz, 1H), 2.90 (dd, J ) 1.2, 18.0 Hz, 1H),
3.77 (td, J ) 4.8, 12.6 Hz, 2H), 3.93 (ddd, J ) 3.9, 9.0, 13.1
Hz, 1H), 4.02 (ddd, J ) 3.9, 8.7, 12.5 Hz, 1H), 4.53 (dd, J )
1.2, 4.2 Hz, 1H); 13C NMR (75.6 MHz, CDCl3) 23.2, 33.8, 53.4,
NMR (75.6 MHz, CDCl3) 14.9, 27.2, 32.5, 32.8, 58.9, 67.7,
152.3, 156.9, 204.3; IR (liquid film) 3700-3100 (br), 1700 (s),
1640 (s) cm-1; HRMS (EI) calcd for C9H14O3 (M+) 170. 0943,
found 170.0941.
Ack n ow led gm en t. The study was supported by
Grant-in-Aid for Scientific Research on Priority Area
“Reactive Organometallics”, No. 07216241, from the
Ministry of Education, Science and Culture.
Su p p or tin g In for m a tion Ava ila ble: Copies of 1H and/
or 13C NMR spectra for 21 compounds 1, 9, 26, 31, 4a ,b, 10,
16a , 18, 17 + 18, 20, 21, 28a ,b, 29, 30b, 33, 35, 36a , and 37
(41 pages). This material is contained in libraries on micro-
fiche, immediately follows this article in the microfilm version
of the journal, and can be ordered from the ACS; see any
current masthead page for ordering information.
56.1, 63.1, 66.9, 93.5, 219.7; IR (liquid film) 1790 (s) cm-1
;
HRMS (EI) calcd for C8H12O3 (M+) 156.0786, found 156.0787.
8-Meth oxy-8-m eth yl-3,7-d ioxon a n -1-on e (30b): 1H NMR
(300 MHz, CDCl3) 1.42 (d, J ) 0.6 Hz, 3H), 1.65-1.88 (m, 2H),
2.13 (d, J ) 12.3 Hz, 1H), 3.23 (s, 3H), 3.30 (td, J ) 4.2, 11.0
Hz, 1H), 3.43 (ddd, J ) 1.5, 5.4, 11.1 Hz), 3.73 (d, J ) 16.2
J O961844X