Reductions, reductive alkylations, and intramolecular cyclizations of acyl silanes with samarium diiodide or tributyltin hydride

Article abstract of DOI:10.1021/jo951980m

A series of acyl silanes including aliphatic-, aromatic-, and bis-acyl silanes, as well as the acyl silanes bearing other substituents such as a bromine atom and alkenyl, succinimide, and carbonyl groups, were prepared, and their reactions with samarium diiodide or tributylstannane were studied. The reactions of acyl silanes occurred in various manners such as reductions, reductive alkylations, intramolecular radical cyclizations, pinacol couplings, aldol reactions, and Tishchenko reactions, depending on the nature of substrates and reaction conditions. Acyl silanes were generally reduced to give the corresponding α-silyl alcohols without transfer of silyl groups. Intramolecular radical cyclizations of 5-hexenoyl silanes and 1-silyl-1,5-pentanedione were realized to give α-silyl cyclopentanols and 1,2-cyclopentanediol derivatives, respectively. On treatment with samarium diiodide in tetrahydrofuran, 1-(trimethylsilyl)-1,6-hexanedione underwent a pinacol coupling reaction in the presence of t-BuOH, whereas it underwent a Tishchenko reaction in the presence of MeOH. The Tishchenko reaction of 1-silyl-1,5-pentanedione gave a δ-silyl-δ-lactone. On treating with samarium diiodide, 1-(trimethylsilyl)-1,5-hexanedione and 1,5-bis(trimethylsilyl)-1,6-hexanedione, underwent, respectively, intramolecular aldol reactions.

Full text of DOI:10.1021/jo951980m

1794
J . Org. Chem. 1996, 61, 1794-1805
Red u ction s, Red u ctive Alk yla tion s, a n d In tr a m olecu la r
Cycliza tion s of Acyl Sila n es w ith Sa m a r iu m Diiod id e or
Tr ibu tyltin Hyd r id e
Tsung-Hsun Chuang, J im-Min Fang,* Weir-Torn J iaang, and Yeun-Min Tsai*
Department of Chemistry, National Taiwan University, Taipei 106, Taiwan, Republic of China
Received November 7, 1995X
A series of acyl silanes including aliphatic-, aromatic-, and bis-acyl silanes, as well as the acyl
silanes bearing other substituents such as a bromine atom and alkenyl, succinimide, and carbonyl
groups, were prepared, and their reactions with samarium diiodide or tributylstannane were studied.
The reactions of acyl silanes occurred in various manners such as reductions, reductive alkylations,
intramolecular radical cyclizations, pinacol couplings, aldol reactions, and Tishchenko reactions,
depending on the nature of substrates and reaction conditions. Acyl silanes were generally reduced
to give the corresponding R-silyl alcohols without transfer of silyl groups. Intramolecular radical
cyclizations of 5-hexenoyl silanes and 1-silyl-1,5-pentanedione were realized to give R-silyl
cyclopentanols and 1,2-cyclopentanediol derivatives, respectively. On treatment with samarium
diiodide in tetrahydrofuran, 1-(trimethylsilyl)-1,6-hexanedione underwent a pinacol coupling reaction
in the presence of t-BuOH, whereas it underwent a Tishchenko reaction in the presence of MeOH.
The Tishchenko reaction of 1-silyl-1,5-pentanedione gave a δ-silyl-δ-lactone. On treating with
samarium diiodide, 1-(trimethylsilyl)-1,5-hexanedione and 1,5-bis(trimethylsilyl)-1,6-hexanedione,
underwent, respectively, intramolecular aldol reactions.
In tr od u ction
2-Alkenoyl silanes are generally used as the acceptors
in Michael reactions,14 Diels-Alder reactions,15 and [3
+ 2] annulations.16 Intramolecular addition of a carbon
radical to acyl silane is facilitated by an irreversible
radical Brook rearrangement.17
Acyl silanes are carbonyl derivatives exhibiting un-
usual chemical and physical properties.1 Acyl silanes,
though sensitive to light and to basic media, behave
frequently as typical ketones such as giving R-silyl
alcohols on treatment with LiAlH42 or borane3 and giving
hydrazones on treatment with hydrazines.4 An acyl
silane can be considered as the synthetic equivalent of
an aldehyde of which hydrogen atom is substituted with
a bulky silyl group. For example, addition of organo-
lithium5 or Grignard reagent6 to an acyl silane gives the
secondary alcohol as a consequence of the Brook rear-
rangement7 to form a strong O-Si bond. The reaction of
an acyl silane with an R-lithio sulfone8 gives silyl enol
ethers via the Brook rearrangement and extrusion of the
sulfonyl group. Metalation of acyl silanes with lithium
diisopropylamide9 or reduction of R-bromoacyl silane with
zinc (Reformatsky reaction)10 give the corresponding
enolates, which undergo aldol reactions with aldehydes
in diastereoselective manners. Aldol reactions between
silyl enol ethers of acylsilanes and acetals are also
realized with the catalysis of Lewis acids.11 Aromatic
acyl silanes function as acyl anion equivalents on treating
with fluoride ion and are trapped with electrophiles.12,13
In recent years, one-electron reductions of carbonyls
with SmI2 to produce samarium ketyl radical anions have
generated a lot of attentions.18 These ketyl radical
intermediates are found useful in the formation of
carbon-carbon bonds via addition to multiple bonds19 or
Barbier-type of coupling reactions with halides.20 When
employed intramolecularly, these methods can be used
to construct cyclic structures.21 Similarly, stannyl radi-
cals generated from tributyltin hydride and carbonyl
compounds have also been used to generate O-stannyl
ketyls.22 These ketyls were shown to add intramolecu-
larly to olefins or carbonyls quite successfully. As part
of our interest in the exploration of the radical reactions
of acyl silanes, we have studied the reactions of acyl
silanes with SmI2 and tributyltin hydride. Experiments
(11) Ricci, A.; Degl’Innocenti, A; Borselli, G.; Reginato, G. Tetrahe-
dron Lett. 1987, 28, 4093.
(12) Degl’Innocenti, A.; Pike, S.; Walton, D. R. M.; Seconi, G.; Ricci,
A.; Fiorenza, M. J . Chem. Soc., Chem. Commun. 1980, 1201.
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(14) Danheiser, R. L.; Fink, D. M. Tetrahedron Lett. 1985, 26, 2509.
(15) Reich, H. J .; Kelly, M. J .; Olson, R. E.; Holtan, R. C. Tetrahedron
1983, 39, 949.
(16) Danheiser, R. L.; Fink, D. M. Tetrahedron Lett. 1985, 26, 2513.
(17) (a) Dalton, J . C.; Bourque, R. A. J . Am. Chem. Soc. 1981, 103,
699. (b) Harris, J . M.; Macinnes, I.; Walton, J . C.; Mailard, B. J . J .
Organometal. Chem. 1991, 403, C25-C28. (c) Tsai, Y.-M.; Cherng, C.-
D. Tetrahedron Lett. 1991, 32, 3515. (d) Curran, D. P.; J iang, W.-T.;
Palovich, M.; Tsai, Y.-M. Synlett 1993, 403. (e) Tsai, Y.-M.; Tang, K.-
H.; J iaang, W.-T. Tetrahedron Lett. 1993, 34, 1303. (f) Tsai, Y.-M., Ke,
B.-W. J . Chin. Chem. Soc. 1993, 40, 641. (g) Robertson, J .; Burrows,
J . N. Tetrahedron Lett. 1994, 35, 3777. (h) Tsai, Y.-M.; Chang, S.-Y. J .
Chem. Soc., Chem. Commun. 1995, 981.
X Abstract published in Advance ACS Abstracts, February 1, 1996.
(1) For reviews on the chemistry, synthesis, and physical properties
of acylsilanes, see: (a) Page, P. C. B.; Klair, S. S.; Rosenthal, S. Chem.
Soc. Rev. 1990, 19, 147. (b) Ricci, A.; Degl’Innocenti, A. Synthesis 1989,
647. (c) Cirillo, P. F.; Panek, J . S. Org. Prep. Proc. Int. 1992, 24, 553.
(2) Brook, A. G. Adv. Organomet. Chem. 1968, 7, 96.
(3) Buynak, J . D.; Strickland, J . B.; Hurd, T.; Phan, A. J . Chem.
Soc., Chem. Commun. 1989, 89.
(4) (a) Yoshida, J .-i.; Itoh, M.; Matsunaga, S.-i.; Isoe, S. J . Org. Chem.
1992, 57, 4877. (b) Bartoli, G.; Bosco, M.; Dalpozzo, R.; Marcantoni,
E. Tetrahedron Lett. 1990, 31, 6935.
(5) For a representive example, see: Reich, H. J .; Eisenhart, E. K.;
Olsen, R. E.; Kelly, M. J . J . Am. Chem. Soc. 1986, 108, 7791.
(6) For a representive example, see: Kuwajima, I.; Enda, J . J . Am.
Chem. Soc. 1985, 107, 5495.
(7) Brook, A. G. Acc. Chem. Res. 1974, 7, 77.
(8) Reich, H. J .; Eisenhart, E. K. J . Org. Chem. 1984, 49, 5282.
(9) Schinzer, D. Synthesis 1989, 179.
(18) For reviews on SmI2, see: (a) Kagan, H. B; Namy, J . L.
Tetrahedron 1986, 42, 6573. (b) Inanaga, J . J . Syn. Org. Chem. 1989,
47, 200. (c) Soderquist, J . A. Aldrichim. Acta 1991, 24, 15. (d) Molander,
G. A. Chem. Rev. 1992, 92, 29. (e) Brandukova, N. E.; Vygodskii, Y.
S.; Vinogradova, S. V. Russ. Chem. Rev. 1994, 63, 345.
(19) For intermolecular ketyl-olefin coupling reactions, see: Ujika-
wa, O.; Inanaga, J .; Yamaguchi, M.; Tetrahedron Lett. 1989, 30, 2837.
(20) Girard, P.; Namy, J . L.; Kagan, H. B. J . Am. Chem. Soc. 1980,
102, 2693.
(10) Horiuchi, Y.; Taniguchi, M.; Oshima, K.; Utimoto, K. Tetrahe-
dron Lett. 1995, 36, 5353.
0022-3263/96/1961-1794$12.00/0 © 1996 American Chemical Society

Reactions of Acyl Silanes with SmI2 or Bu3SnH
J . Org. Chem., Vol. 61, No. 5, 1996 1795
Sch em e 1
Sch em e 2
Sch em e 3
were generally carried out with HgO/BF3‚OEt2 in aque-
ous THF solution.25 In addition to the desired acyl silane
33 (81%), a side-product 34 (13%) was obtained from a
transacetalation when 32 was hydrolyzed in such condi-
tions. The problem was circumvented by hydrolysis in
aqueous acetone solution, giving exclusively 33 in 91%
yield. In certain cases, the oxidizing agent Ce(NH4)2-
(NO3)626 or PhI(CF3CO2)227 were also used for removal of
dithiane moiety.
Bis[2-(trialkylsilyl)-1,3-dithianes] 24-27, the precur-
sors of bis-acyl silanes 28-31, were obtained by alkyla-
tions of the corresponding 2-(trialkylsilyl)-1,3-dithianes
(22 or 23) with appropriate dibromides (0.5 equiv).
Alkylation of 2-(trimethylsilyl)-1,3-dithiane (22) with 1,4-
dibromobutane (1 equiv) gave the dithiane 40, whereas
alkylation of 1,3-dithiane with 1,5-dibromopentane (0.5
equiv) afforded the bis-dithiane 41. Reaction of the
bromide 40 with 2-lithio-1,3-dithiane and monosilylation
of the bis-1,3-dithiane 41 gave 43 and 44, which were
subsequently hydrolyzed with HgO/BF3‚OEt2 to give
formylalkanoyl silanes 47 (60%) and 48 (55%). Formyl-
alkanoyl silane 46 was synthesized similarly by monosi-
lylation of the bis-dithiane 39 followed by hydrolysis (70%
from 39). The bis-dithiane 39 was in turn synthesized
(55%) from the reaction of 1,3-propanedithiol with glut-
araldehyde.28 Sequential transacetalation (cat. TsOH,
Me2CO) and hydrolysis (HgO/BF3‚OEt2) of the dithiane
45, prepared from 22 and 5-bromopentanal ethylene
acetal,29 also led to the acyl silane 47. 5-Oxopentanoyl
are designed to examine the reactivities of the silyl
substituted ketyls with various functionalities. The
results of these experiments are described in this paper.
Resu lts a n d Discu ssion
Acyl silanes 223b and 14-21 were generally prepared
from 1,3-dithianes (Scheme 1) according to Brook and
Corey’s method.23 Hexanoyl silane 424 was prepared from
hydroboration-oxidation of 1-hexynyl silane 3. Prepara-
tion of bis-acyl silanes 28-31 (Scheme 2), 5-oxohexanoyl
silane 33 (Scheme 3), and formylalkanoyl silanes 37 and
46-48 (Scheme 4) were also illustrated. Hydrolysis of
2-silyl-1,3-dithianes to the corresponding acyl silanes
(21) (a) Molander, G. A.; Kenny, C. Tetrahedron Lett. 1987, 28, 4367.
(b) Fevig, T. L.; Elliott, R. L.; Curran, D. P. J . Am. Chem. Soc. 1988,
110, 5064. (c) Molander, G. A.; Mckie, J . A. J . Org. Chem. 1991, 56,
4112.
(22) (a) Beckwith, A. L. J .; Roberts, D. H. J . Am. Chem. Soc. 1986,
108, 5893. (b) Sugawara, T.; Otter, B. A.; Ueda, T. Tetrahedron Lett.
1988, 29, 75. (c) Enholm, E. J .; Burroff, J . A. Tetrahedron Lett. 1992,
33, 1835. (d) Zelechonok, Y.; Silverman, R. B. J . Org. Chem. 1992, 57,
5785. (e) Rawal, V. H.; Krishnamurthy, V.; Fabre, A. Tetrahedron Lett.
1993, 34, 2899. (f) Lee, E.; Tae, J . S.; Chong, Y. H.; Park, Y. C.
Tetrahedron Lett. 1994, 35, 129. (g) Hays, D. S.; Fu, G. C. J . Am. Chem.
Soc. 1995, 117, 7283. (h) Enholm, E. J .; Kinter, K. S. J . Org. Chem.
1995, 60, 4850.
(25) Vedejs, E.; Fuchs, P. L. J . Org. Chem. 1971, 36, 366.
(26) (a) Ho, T.-L; Ho, H. C.; Wong, C. M. J . Chem. Soc., Chem.
Commun. 1972, 791. (b) Ho, H. C.; Ho, T.-L; Wong, C. M. Can. J . Chem.
1972, 50, 2718.
(23) (a) Brook, A. G.; Duff, J . M.; J ones, P. F.; Davis, N. R. J . Am.
Chem. Soc. 1967, 89, 431. (b) Corey, E. J .; Seebach, D.; Freedman, R.
J . Am. Chem. Soc. 1967, 89, 434.
(27) Stork, G.; Zhao, K. Tetrahedron Lett. 1989, 30, 287.
(28) Corey, E. J .; Seebach, D. Angew. Chem., Int. Ed. Engl. 1965,
4, 1077.
(24) Miller, J . A.; Zweifel, G. Synthesis 1981, 288.
(29) Kulkarni, S.; Patil, V. D. Heterocycles 1982, 18, 163.

1796 J . Org. Chem., Vol. 61, No. 5, 1996
Chuang et al.
Sch em e 4
Sch em e 5
characterized by a triplet signal occurring at δ 69.9 (J )
20 Hz) for the carbinyl carbon. The reaction mechanism
is shown (Scheme 5). Reduction of the acyl silane by
sequential transfers of two electrons from SmI2 (2 equiv)
might form an organosamarium B33 to account for the
deuteration and alkylations. Benzyl phenyl ketone might
be derived from a pinacolate intermediate C31 via se-
quential transfers of silyl groups and hydrolysis, though
the pinacol corresponding to C was not isolated.
Hexanoyl silane 4 was reduced with SmI2 to give the
alcohol 53 (50%). Selective reductions of acyl silanes 14,
15, and 16 with SmI2 were realized, giving 54 (50%), 55
(63%), and 56 (52%), respectively, with intact succinimide
and bromophenyl moieties. 5-Bromopentanoyl silane 17
was reduced with SmI2, followed by the intramolecular
alkylation, to give exclusively 1-silylcyclopentanol 57
(47%). The reaction of 6-bromohexanoyl silane 18 gave
1-silylcyclohexanol 58 (45%) and an open-chain alcohol
59 (17%). 7-Bromoheptanoyl silane 19 was simply
reduced to the corresponding silyl heptanol 60 (55%),
silane 37 was prone to undergo intramolecular cyclization
to give a dihydropyran derivative 38 if excess of acid
existed in the reaction media.30
The reaction of benzoyl silane 2 with SmI2 in THF gave
simply the reduction product 49 (63%)31 even in the
absence of proton source. When the reaction was con-
ducted in the presence of HMPA, benzyl phenyl ketone
(52) was obtained (30%) in addition to the silyl alcohol
49 (47%). Benzaldehyde reacts with SmI2 in the presence
of HMPA to give a phenyl-carbonyl coupling product,
4-(1-hydroxybenzyl)benzaldehyde.32 Acetophenone fol-
lows the similar reaction pathway.32 However, benzoyl
silane did not undergo such phenyl-carbonyl coupling
reaction. Treatment of benzoyl silane 2 with SmI2 in the
presence of an electrophile such as t-BuOD, allyl bromide,
or benzyl bromide gave 49-d (62%) and alkylated prod-
ucts 50 (84%) and 51 (91%). Compound 49-d was
(30) Tsai, Y.-M.; Nieh, H.-C.; Cherng, C.-D. J . Org. Chem. 1992, 57,
7010.
(32) Shiue, J . S.; Lin, C. C.; Fang, J . M. Tetrahedron Lett. 1993, 34,
335.
(31) Taniguchi, Y.; Fuji, N.; Makioka, Y.; Takaki, K., Fujiwara, Y.
Chem. Lett. 1993, 1165.
(33) (a) Molander, G. A.; Kenny, C. J . Org. Chem. 1991, 56, 1439.
(b) Curran, D. P.; Totleben, M. J . Am. Chem. Soc. 1992, 114, 6050.

Reactions of Acyl Silanes with SmI2 or Bu3SnH
J . Org. Chem., Vol. 61, No. 5, 1996 1797
Sch em e 6
Sch em e 7
methylsilyl groups on the same face as indicated by the
NOE study, i.e. irradiation of the Me3Si signal (at δ 0.08)
causing a 22% NOE of the adjacent methyl group (at δ
0.87). The reaction of 5-hexenoylmethyldiphenylsilane
(21) with SmI2 in THF/HMPA/t-BuOH afforded the silyl
hexenol 62 (48%) and the silyl cyclopentanol 66 (32%).
The cyclization product 66 existed as two diastereomers,
of which the ratio (cis/trans) varied from 70/30 to 40/60
depending on the amounts of HMPA (1-8 equiv) and
t-BuOH (1-2 equiv). The reaction in THF/t-BuOH
(without HMPA) gave more reduction product 62 (52%),
accompanied by 66 (38%, cis/trans ) 55:45). The reaction
in THF (without t-BuOH or HMPA) gave 62 (13%), 66
(18%, cis/trans ) 46:54), and a diol 67 (38%, a mixture
of diastereomers). In the presence of allyl bromide or
benzyl bromide, the reaction of 21 with SmI2 gave
Barbier-type products 63 (84%) or 64 (79%), no intramo-
lecular cyclization occurred.
The reaction of 21 with tributyltin hydride revealed
that the cyclization was less efficient. The major product
obtained was the uncyclized alcohol 62 (45%). Cyclized
alcohol 66 was obtained in 12% as a mixture of cis/ trans
(5:1) isomers. Silyl ethers cis-68 (9%) and trans-68 (6%)
were also isolated (Scheme 7). These silyl ethers were
originated from initial addition of tin radical to the
terminal olefin followed by cyclization with the acyl
silane.17c The stereochemistry of 68 was determined by
presumably the intramolecular alkylation to form a
seven-membered ring was energetically unfavorable.
1
comparison of the H NMR chemical shifts with those of
2-methyl-1-(methyldiphenylsilyloxy)cyclopentane.17e The
H-1 resonance of cis-68 had a larger chemical shift (at δ
4.05) than that of trans-68 (at δ 3.74) in agreement with
the trend in 2-methyl-1-(methyldiphenylsilyloxy)cyclo-
pentane, i.e. the H-1 of cis-isomer appearing at δ 4.16
and that of trans-isomer appearing at δ 3.77.
On treating with SmI2 or Bu3SnH, alkenoyl silanes 20
and 21 having terminal vinyl groups appeared to proceed
with similar mechanisms of radical cyclizations (Scheme
6).34 The chair transition state E having the trimethyl-
silyl group on the equatorial position accounted for the
formation of silyl cyclopentanol cis-65. The samarium
ion with coordination of HMPA and other ligands might
exert severe eclipsed interaction in the transition state
F . The dipole-dipole interaction between the oxide and
double bond might also disfavor F . The preference of G
over H diminished when a bulkier Ph2MeSi group was
used, so that both pathways proceeded to give two
diastereomers of 66. Similar stereochemistry has been
reported in the SmI2-promoted ketyl-olefin radical cy-
clization reactions.34e,f Compound 66 was also derived
from the addition of silyl substituted O-stannyl ketyl to
the olefin. The stereochemical outcome (cis/trans ) 5:1)
5-Hexenoyltrimethylsilane (20) was treated with SmI2
in the presence of HMPA (1-2 equiv) and t-BuOH (2
equiv) to give the corresponding silyl hexenol 61 (32%)
and a silyl cyclopentanol 65 (26%) derived from the
intramolecular radical cyclization (Scheme 6). Com-
pound 65 (cis-configuration) had the methyl and tri-

1798 J . Org. Chem., Vol. 61, No. 5, 1996
Chuang et al.
Sch em e 8
Sch em e 9
case, SmI2 presumably functioned as a Lewis acid to
induce the acyl silane to form an (E)-enolate and the
subsequent aldol reaction proceeded with a chelate mode
P .37
indicated that the chair transition state I, in which the
O-stannyl group occupied the axial position,34,35 was
preferred over J . Diol 67 was obtained presumably by
addition of 21 with an organosamarium L, which was
resulted from further reduction of the radical cyclization
intermediate K.
1,8-Bis(trimethylsilyl)-1,8-octanedione (31) was re-
duced with SmI2 (Scheme 8) to give 8-hydroxy-1,8-bis-
(trimethylsilyl)octanone (71, one-site reduction, 53%) and
1,8-bis(trimethylsilyl)-1,8-hexanediol (74, two-site reduc-
tion, 36%). 1,5-Bis(trimethylsilyl)-1,5-pentanedione (28)
underwent a one-site reduction with SmI2 (2 equiv), and
the product 5-hydroxy-1,5-bis(trimethylsilyl)pentanone
(69) further condensed to its dihydropyran form 75.
When bis-acyl silane 29 was treated with tributyltin
hydride (2 equiv) in refluxing benzene in the presence of
catalytic amount of AIBN, diol 72 was obtained in 12%
yield along with 52% of dihydropyran 76. Apparently,
the silyl substituted O-stannyl ketyl did not add to the
acylsilane intramolecularly. This is in sharp contrast to
the related intramolecular 1,5-cyclizations of alkyl sub-
stituted carbon radicals to acyl silanes.17c
Treatment of 1,6-bis(trimethylsilyl)-1,6-hexanedione
(30) with SmI2 (2.5 equiv) afforded mainly an aldol
product 77 (46%)36 in addition to the one-site reduction
product 70 (13%) and the two-site reduction product 73
(9%). An NOE study, i.e. irradiation of the resonance of
Me3Si group (at δ -0.05) causing a 20% NOE of the
resonance of R-proton, established that aldol 77 had the
hydroxyl and acyl groups on the same face. In such a
1-(Trimethylsilyl)-1,5-hexanedione (33) reacted with
SmI2 (eq 1) to give an aldol product 78 (56%) but no
reduction product. No reaction of 33 occurred in the
presence of a proton source (MeOH or t-BuOH), and the
starting material was recovered. On the other hand,
1-(trimethylsilyl)-1,5-pentanedione (37) reacted with SmI2
(Scheme 9) in the presence of MeOH to give a δ-silyl-δ-
lactone 79 (79%). The reaction was presumably initiated
by addition of MeOH to the aldehyde group to form a
hemiacetal with catalysis of SmI2. The intermediate Q
underwent Tishchenko reaction36,38 by hydride transfer
to the acyl silane R and led to the observed lactone 79.
1-(Trimethylsilyl)-1,6-hexanedione (47) reacted similarly
with SmI2 (Scheme 9) in THF/MeOH to give a methyl
ester 80 (62%). The reaction in THF/t-BuOH gave,
however, pinacols 81 resulted from reductive coupling of
the formyl groups.36,39
When 1-(dimethylphenylsilyl)-1,5-pentanedione (46)
was treated with 1.5 equiv of tributyltin hydride (Scheme
10), cyclization did occur to give monosilylated 1,2-
cyclopentanediol cis-82 (21%) and trans-82 (18%), and cis-
diol 83 (32%). Diol 83 was resulted from desilylation of
cis-82 during silica gel column chromatographic purifica-
tion. The stereochemistry of 82 was determined by
comparison with the authentic samples prepared by
silylation of the commercially available diols. The reac-
tion of 1-(dimethylphenylsilyl)-1,7-heptanedione (48) with
tributyltin hydride (1 equiv) gave only silyl alcohol 84 in
(34) For general radical cyclizations, see: (a) Beckwith, A. L. J .
Tetrahedron 1981, 37, 3073. (b) Beckwith, A. L. J .; Schiesser, C. H.
Tetrahedron 1985, 41, 3925. (c) Spellmeyer, D. C.; Houk, K. N. J . Org.
Chem. 1987, 52, 959. For O-stannyl ketyl related cyclizations, see: (d)
Hon, Y.-S.; Sun, P.-P.; Lu, H.-L.; Chang, N.-C. J . Chin. Chem. Soc.
1994, 41, 445. For O-samarium ketyl related cyclizations, see: (e)
Molander, G. A.; Mckie, J . A. J . Org. Chem. 1992, 57, 3132. (f)
Molander, G. A.; Kenny, C. J . Am. Chem. Soc. 1989, 111, 8236. (g)
Molander, G. A.; Mckie, J . A. J . Org. Chem. 1995, 60, 872.
(37) Heathcock, C. H. in Comprehensive Organic Synthesis; Trost,
B. M., Fleming, I., Eds.; Pergamon Press: Oxford, 1991; Vol. 2, Chap.
1.5.
(35) Enholm, E. J .; Prasad, G. Tetrahedron Lett. 1989, 30, 4939.
(36) Some aldol products have been observed in the SmI2(Ot-Bu)
promoted reaction of 5-oxohexanal, see: Unenishi, J .; Masuda, S.;
Wakabayashi, S. Tetrahedron Lett. 1991, 32, 5097.
(38) Evans, D. A.; Hoveyda, A. H. J . Am. Chem. Soc. 1990, 112, 6447
and the references cited therein.
(39) Namy, J . L.; Souppe, J .; Kagan, H. B. Tetrahedron Lett. 1983,
24, 765.

Reactions of Acyl Silanes with SmI2 or Bu3SnH
J . Org. Chem., Vol. 61, No. 5, 1996 1799
Sch em e 10
successfully alkylated intra- or intermolecularly to give
R-silyl cycloalkanols or tertiary R-silyl alcohols. The
reaction of benzoyl trimethylsilane with SmI2 in the
presence of HMPA also afforded a side product, benzyl
phenyl ketone, presumably derived from the picanol
coupling reaction followed by sequential transfers of the
silyl groups.
Intramolecular radical cyclizations of 5-hexenoyl si-
lanes were effected with SmI2 or Bu3SnH to give R-silyl
cyclopentanols. The radical cyclizations proceeded with
similar mechanisms via the chairlike transition states,
though SmI2 appeared to be a better reagent than Bu3-
SnH in these reactions. The radical cyclizations favored
to give the products having the cis-configuration, though
the stereoselectivity depended on the reagents and the
bulkiness of silyl groups. Treatment of 1-silyl-1,5-pen-
tanedione with Bu3SnH (Scheme 10) also yielded in-
tramolecular cycliaztion products. Treatments of bis-acyl
silanes with SmI2 or Bu3SnH generally gave reduction
products (one- or two-site reduction). No radical cycliza-
tion product was formed presumably due to the steric
effect between the two bulky silyl groups.
The pinacol coupling reaction of 1-(trimethylsilyl)-1,6-
hexanedione was carried out with SmI2 in the presence
of t-BuOH (Scheme 9). On the other hand, a Tishchenko
reaction occurred to give methyl 6-hydroxy-6-(trimeth-
ylsilyl)hexanoate when the reaction was conducted in the
presence of MeOH. The reaction of 1-silyl-1,5-pentanedi-
one with SmI2 in the presence of MeOH proceeded
similarly to give a δ-silyl-δ-lactone.
Unprecedent intramolecular aldol reactions of 1-(tri-
methylsilyl)-1,5-hexanedione was observed on treating
with SmI2 (eq 1). Under the similar reaction conditions,
an aldol reaction of 1,5-bis(trimethylsilyl)-1,6-hexanedi-
one (Scheme 8) occurred by forming an (E)-enolate from
one of the acyl silane group and added intramolecularly
to the other acyl silane via a chelate transition state.
In summary, we have prepared a series of acyl silanes
including aliphatic-, aromatic-, and bis-acyl silanes, as
well as the acyl silanes bearing other substituents such
as bromine atom, alkenyl, succinimide and carbonyl
groups. The reactions of acyl silanes with SmI2 or Bu3-
SnH occurring in various manners such as reductions,
reductive alkylations, intramolecular radical cyclizations,
pinacol couplings, aldol reactions, and Tishchenko reac-
tions were of synthetic interest.
38% yield along with unreacted starting material. It is
noted that no cyclization of this type was observed in the
related system of 37 when SmI2 was used.
Mechanistically, there are two possible pathways to
account for the formation of 82. Stannyl radical addition
to the formyl group would give O-stannyl ketyl S which
could cyclize onto the acyl silane group to give the â-silyl
alkoxy radical T. Radical Brook rearrangement of T led
to the formation of U.17 Alternatively, the stannyl radical
could also add to the acyl silane group to give the ketyl
V. Addition of this radical to the formyl group would give
alkoxy radical W. In principle, a 1,4-stannyl shift might
occur to give T.22g,40 Currently, we have no evidence to
determine which pathway is preferred; however, the
preferential reduction of the acyl silane moiety in 48 is
worth noting. The stereochemical outcome was deter-
mined at the stage of hydrogen abstraction of radical U.
The moderate cis-selectivity, (cis-82 + 83)/trans-82 ) 3:1,
was likely due to the approaching of tributyltin hydride
opposite to the stannyloxy group.41 The decreased cis-
selectivity (1.5:1) in the formation of 67 (Scheme 6) was
possibly due to the presence of a bulkier (tributylstannyl)-
methyl group which might destabilize cis-67. Compared
with the case of 29 (Scheme 8), we attributed the lack of
radical cyclization reactivity of 29 to the steric effect
between the two bulky silyl groups. Removal of one of
the silyl groups facilitated the cyclization.
Exp er im en ta l Section
Melting points are uncorrected. 1H NMR spectra were
recorded at 200, 300, or 400 MHz; 13C NMR spectra were
recorded at 50, 75, or 100 MHz. Tetramethylsilane (δ ) 0
1
ppm) was used as internal standard in H NMR spectra. Mass
spectra were recorded at an ionizing voltage of 70 eV or 20
eV. Merck silica gel 60F sheets were used for analytical thin-
layer chromatography. Column chromatography was per-
formed on SiO2 (70-230 mesh); gradients of EtOAc and
n-hexane were used as eluents. High-pressure liquid chro-
Con clu sion
matography was carried out on
a liquid chromatograph
Acyl silanes were generally reduced with SmI2 in THF
to give the corresponding R-silyl alcohols without transfer
of silyl groups (via Brook rearrangements). Bromophenyl
or succinimide substituents were inert to SmI2 under the
reaction conditions. The presumed organosamarium
species such as that depicted in B (Scheme 5) were
equipped with a refractive index detector. The samples were
analyzed and/or separated on a Hibar Lichrosorb Si 60 (7 µm)
column (25 cm × 1 cm) with the indicated eluent with a 5 mL/
min flow rate. Benzene and THF were distilled from sodium
benzophenone ketyl under N2.
Gen er a l P r oced u r e for th e P r ep a r a tion of 2-(Tr ia lk yl-
silyl)-1,3-d ith ia n es. To a cold (0 °C) stirred solution of 1,3-
dithiane (2 g, 16.7 mmol) in THF (16 mL) was added dropwise
BuLi (15.1 mL of 1.6 M solution in hexane, 22.5 mmol). The
mixture was stirred for 10 min, and then trialkylsilyl chloride
(16.7 mmol) was added in one portion. The resulting solution
(40) (a) Davies, A. G.; Tse, M.-W. J . Organomet. Chem. 1978, 155,
25. (b) Hasegawa, E.; Ishiyama, K.; Kato, T.; Horaguchi, T.; Shimizu,
T. J . Org. Chem. 1992, 57, 5352.
(41) Giese, B. Angew. Chem., Int. Ed. Engl. 1989, 28, 969.

1800 J . Org. Chem., Vol. 61, No. 5, 1996
Chuang et al.
was stirred for another 30 min and then slowly warmed to
room temperature (32 °C). The reaction was quenched by
addition of aqueous NH4Cl. The mixture was concentrated,
and the residue was taken up in EtOAc (50 mL). The organic
phase was washed with brine (2 × 25 mL), dried (Na2SO4),
and concentrated on rotary evaporation to give a crude product
of 2-(trialkylsilyl)-1,3-dithiane. Separation of the product was
accomplished by silica gel chromatography using EtOAc/
hexane as eluent.
Gen er a l P r oced u r e for th e P r ep a r a tion of 2-Alk yl-2-
(tr ia lk ylsilyl)-1,3-d ith ia n es. To a cold (0 °C) stirred solution
of 2-(trialkylsilyl)-1,3-dithiane (5-10 mmol, 1 equiv) in THF
(30 mL) was added dropwise BuLi (1.2 equiv of 1.6 M solution
in hexane). The mixture was stirred for 10 min, and an
alkylating agent (1.2 equiv) was added in one portion. The
resulting solution was stirred for another 30 min and then
slowly warmed to room temperature (32 °C). The reaction was
quenched by addition of aqueous NH4Cl. The mixture was
concentrated, and the residue was taken up in EtOAc (30 mL).
The organic phase was washed with brine (2 × 15 mL), dried
(Na2SO4), and concentrated on rotary evaporation to give a
crude product of 2-alkyl-2-(trialkylsilyl)-1,3-dithiane. Separa-
tion of the product was accomplished by silica gel chromatog-
raphy using EtOAc/hexane as eluent.
3-(2-Br om op h en yl)-1-(tr im eth ylsilyl)p r op a n on e (15). A
crude 2-[2-(o-bromophenyl)ethyl]-2-(trimethylsilyl)-1,3-dithiane
(7, 0.92 g, 2.4 mmol), prepared from 1-bromo-2-(2-bromoethyl)-
benzene (0.69 g, 2.61 mmol) and 2-(trimethylsilyl)-1,3-dithiane
(0.5 g, 2.65 mmol), was treated with HgO (1.06 g, 4.8 mmol)
and BF3‚OEt2 (0.59 mL, 4.8 mmol) to give the title compound
15 (302 mg, 44%). An oil; TLC (EtOAc/hexane (2:98)) Rf )
0.17; IR (neat) 3061, 2956, 2897, 1635, 1463, 1246, 1040 cm-1
;
1H NMR (CDCl3) δ 0.15 (s, 9 H), 2.90 (s, 4 H), 6.93-7.02 (m,
1 H), 7.10-7.18 (m, 2 H), 7.45 (d, J ) 7.8 Hz, 1 H); 13C NMR
(CDCl3) δ -3.4 (q, 3 C), 28.7 (t), 47.7 (t), 120.4 (s), 127.3 (d),
127.5 (d), 130.4 (d), 132.6 (d), 140.7 (s), 246.0 (s); MS m/ z (rel
intensity) 286 (M+, 10), 271 (17), 269 (16), 243 (13), 241 (12),
205 (29), 73 (100); HRMS calcd for C12H17BrOSi 286.0211,
found 286.0227.
3-(2-Br om op h e n yl)-1-(d ip h e n ylm e t h ylsilyl)p r op a n -
on e (16). A crude 2-[2-(o-bromophenyl)ethyl]-2-(diphenyl-
methylsilyl)-1,3-dithiane (8, 2.2 g, 4.4 mmol), prepared from
1-bromo-2-(2-bromoethyl)benzene (1.32 g, 5 mmol) and 2-(diphe-
nylmethylsilyl)-1,3-dithiane (1.58 g, 5 mmol), was treated with
HgO (1.9 g, 8.8 mmol) and BF3
‚OEt2 (1.08 mL, 8.8 mmol) to
give the title compound 16 (470 mg, 23%). An oil; TLC (EtOAc/
hexane (2:98)) Rf ) 0.1; IR (neat) 3066, 3018, 2958, 1635, 1462,
1
1251, 996 cm-1; H NMR (CDCl3) δ 0.74 (s, 3 H), 2.95 (m, 4
H), 6.99-7.14 (m, 3 H), 7.33-7.46 (m, 7 H), 7.55 (d, J ) 7.8
Hz, 4 H); 13C NMR (CDCl3) δ -5.5 (q), 28.8 (t), 48.9 (t), 124.1
(s), 127.3 (d), 127.5 (d), 128.1 (d, 4 C), 130.0 (d, 2 C), 130.4 (d),
132.3 (s, 2 C), 132.6 (d), 138.4 (d, 4 C), 140.4 (s), 242.6 (s); MS
m/ z (rel intensity) 409 (M+, 40), 367 (60), 358 (25), 252 (8),
225 (36), 197 (100), 137 (10); HRMS calcd for C22H21BrOSi
410.0524, found 410.0537.
Gen er a l P r oced u r e for th e P r ep a r a tion of Acyl Si-
la n es. Meth od A. To a mixture of BF3‚OEt2 (0.73 mL, 6
mmol), Celite (1 g), and HgO (1.3 g, 6 mmol) in 10 mL of THF/
H2O (v/v ) 85:15) was added 2-alkyl-2-(trialkylsilyl)-1,3-
dithiane in THF (6 mL) dropwise at room temperature (28 °C).
The mixture was stirred for 1 h at room temperature (28 °C),
after which the mixture was filtered through a short column
containing silica gel and Celite. The solution was diluted with
ether (30 mL), washed with brine (2 × 15 mL), dried (Na2-
SO4), and concentrated on rotary evaporation to give a crude
product of acyl silane. Separation of the product was ac-
complished by silica gel chromatography using EtOAc/hexane
as eluent.
Meth od B. To a cold (-30 °C) solution of 2-alkyl-2-
(trialkylsilyl)-1,3-dithiane (10 mmol, 1 equiv), Celite (60 mg/
mmol), and NaHCO3 (1.5 equiv) in CH2Cl2/CH3CN (v/v ) 3:2,
50 mL) was added ammonium cerium(IV) nitrate (CAN, 3
equiv) in CH3CN/H2O (v/v ) 15:1, 20 mL) over a period of 10
min. The resulting solution was stirred at -30 °C for 5 min
and then diluted with 100 mL of ether, filtered, and partitioned
with 50 mL of water. The ethereal phase was washed with
brine (2 × 20 mL), dried over Na2SO4, and filtered, and the
filtrate was concentrated on rotary evaporation to give a crude
product of acyl silane. Separation of the product was ac-
complished by silica gel chromatography using EtOAc/hexane
as eluent.
5-Br om o-1-(d im et h ylp h en ylsilyl)p en t a n on e (17).
A
crude 2-(4-bromobutyl)-2-(dimethylphenylsilyl)-1,3-dithiane (9,
1.60 g), prepared from 2-(dimethylphenylsilyl)-1,3-dithiane
(0.76 g, 3 mmol) and 1,4-dibromobutane (1.2 mL, 9 mmol), was
treated with HgO (1.3 g, 6 mmol) and BF3‚OEt2 (0.73 mL, 6
mmol) to give the title compound 17 (0.6 g, 67%). An oil; TLC
(EtOAc/hexane (2:98)) Rf ) 0.14; IR (neat) 2944, 1642, 1428,
1
1250, 1110, 836, 818 cm-1; H NMR (CDCl3) δ 0.47 (s, 6 H),
1.53-1.74 (m, 4 H), 2.57 (t, J ) 6.0 Hz, 2 H), 3.27 (t, J ) 6.0
Hz, 2 H), 7.35-7.55 (m, 5 H); 13C NMR (CDCl3) δ -4.8 (q, 2
C), 20.7 (t), 32.0 (t), 33.2 (t), 47.4 (t), 128.1 (d, 2 C), 129.9 (d),
138.8 (d, 2 C), 154.2 (s), 245.4 (s); MS m/ z (rel intensity) 299
(M+ - 1, 0.5), 297 (0.5), 271 (2), 269 (2), 201 (8), 199 (8), 135
(100); HRMS calcd for C13H19BrOSi 300.0369, found 300.0367.
6-Br om o-1-(ter t-bu tyld im eth ylsilyl)h exa n on e (18). A
crude 2-(5-bromopentyl)-2-(tert-butyldimethylsilyl)-1,3-dithiane
(10, 1.04 g), prepared from 2-(tert-butyldimethylsilyl)-1,3-
dithiane (0.7 g, 3 mmol) and 1,5-dibromopenane (1.2 mL, 9
mmol), was treated with HgO (1.39 g, 6 mmol) and BF3‚OEt2
(0.73 mL, 6 mmol) to give the title compound 18 (0.61 g, 70%).
An oil; TLC (EtOAc/hexane (5:95)) Rf ) 0.3; IR (neat) 2927,
2854, 1634, 1459, 1248, 837, 775 cm-1; 1H NMR (CDCl3) δ 0.15
(s, 6 H), 0.90 (s, 9 H), 1.31-1.59 (m, 4 H), 1.82 (quin, J ) 7.2
Hz, 2 H), 2.58 (t, J ) 7.0 Hz, 2 H), 3.37 (t, J ) 6.8 Hz, 2 H);
13C NMR (CDCl3) δ -7.0 (q, 2 C), 16.4 (s), 20.9 (t), 26.3 (q, 3
C), 27.7 (t), 32.6 (t), 33.5 (t), 49.8 (t), 247.0 (s); MS m/ z (rel
intensity) 294 (M+ + 1, 2), 237 (6), 213 (9), 195 (26), 171 (8),
115 (82), 73 (100); HRMS calcd for C12H25BrOSi 292.0858,
found 292.0855.
Ben zoyltr im eth ylsila n e (2).23b 2-Phenyl-2-(trimethylsi-
lyl)-1,3-dithiane (1) was hydrolyzed with HgO and HgCl2 in
aqueous MeOH to give the acyl silane 2 (82%) according to
literature.23
1-(Tr im eth ylsilyl)h exa n on e (4).24 Compound 4 was pre-
pared from hydroboration-oxidation of 1-hexynyltrimethyl-
silane 3 (77%) according to literature.24
N-[3-Oxo-3-(t r im et h ylsilyl)p r op yl]p yr r olid in e-2,5-d i-
on e (14). Alkylation of 2-(trimethylsilyl)-1,3-dithiane (5.04
mmol) with 2-chloroethanol tetrahydropyran ether (2.16 g, 6.05
mmol), followed by hydrolysis (cat. TsOH, MeOH, 25 °C, 2 h),
gave 2-(2-hydroxyethyl)-2-(trimethylsilyl)-1,3-dithiane30 (0.83
g, 70%). Solid, mp 46-48 °C. Condensation of the alcohol
(0.80 g, 3.4 mmol) with succinimide (0.4 g, 4 mmol) according
to Mitsunobu procedure, using PPh3 (1.6 g, 5.1 mmol) and
diethyl azodicarboxylate (0.53 mL, 3.4 mmol) in THF at 0 °C
for 12 h, gave 2-[(2-succinimidyl)ethyl]-2-(trimethylsilyl)-1,3-
dithiane (6, 0.84 g, 77%). Solid, mp 134-136 °C. The dithiane
6 (0.7 g, 2.57 mmol) was treated with CAN to give the title
compound 14 (450 mg, 82%). Solid, mp 125-126 °C; TLC
(EtOAc/hexane (50:50)) Rf ) 0.1; IR (KBr) 2960, 1708, 1630,
1436, 1397, 1250, 1152 cm-1; 1H NMR (CDCl3) δ 0.16 (s, 9 H),
2.66 (s, 4 H), 2.87 (t, J ) 7.0 Hz, 2 H), 3.70 (t, J ) 7.2 Hz, 2
H); 13C NMR (CDCl3) δ -3.4 (q, 3 C), 28.0 (t, 2 C), 32.9 (t),
44.9 (t), 176.9 (s, 2 C), 245.0 (s); MS m/ z (rel intensity) 227
(M+, 1), 212 (3), 199 (15), 170 (13), 156 (14), 103 (5), 73 (100);
HRMS calcd for C10H17NO3Si 227.0978, found 227.0974.
7-Br om o-1-(tr im eth ylsilyl)h eptan on e (19). A crude 2-(6-
bromohexyl)-2-(trimethylsilyl)-1,3-dithiane (11, 0.97 g), pre-
pared from 2-(trimethylsilyl)-1,3-dithiane (0.58 g, 3 mmol) and
1,6-dibromohexane (1.38 mL, 9 mmol), was treated with HgO
(1.39 g, 6 mmol) and BF3‚OEt2 (0.73 mL, 6 mmol) to give the
title compound 19 (0.52 g, 65%). An oil; TLC (EtOAc/hexane
(10:90)) Rf ) 0.5; IR (neat) 2934, 2858, 1634, 1457, 1246, 844,
1
750 cm-1; H NMR (CDCl3) δ 0.13 (s, 9 H), 1.16-1.54 (m, 6
H), 1.78 (quin, J ) 6.8 Hz, 2 H), 2.54 (t, J ) 7.0 Hz, 2 H), 3.33
(t, J ) 6.8 Hz, 2 H); 13C NMR (CDCl3) δ -3.2 (q, 3 C), 21.7 (t),
27.8 (t), 28.3 (d), 32.4 (t), 33.6 (t), 48.0 (t), 248.0 (s); MS m/ z
(rel intensity) 251 (M+ - 15, 1), 249 (1), 185 (2), 139 (6), 101
(6), 95 (15), 73 (100); HRMS calcd for C10H21BrOSi 266.0524,
found 266.0527.
1-(Tr im eth ylsilyl)-5-h exen on e (20). 2-(4-Pentyl)-2-(tri-
methylsilyl)-1,3-dithiane (12, 1.83 g, 7 mmol), prepared from
2-(trimethylsilyl)-1,3-dithiane (1.92 g, 10 mmol) and 5-bromo-

Reactions of Acyl Silanes with SmI2 or Bu3SnH
J . Org. Chem., Vol. 61, No. 5, 1996 1801
1-pentene (1.42 mL, 12 mmol), was treated with CAN (11.5 g,
21 mmol) to give the title compound 20 (0.91 g, 76%). An oil;
TLC (EtOAc/hexane (2:98)) Rf ) 0.3; IR (neat) 2954, 1634,
1436, 1399, 1247, 911, 845 cm-1; 1H NMR (CDCl3) δ 0.12 (s, 9
H), 1.55 (quin, J ) 7.2 Hz, 2 H), 1.95 (q, J ) 7.2 Hz, 2 H), 2.53
(t, J ) 7.2 Hz, 2 H), 4.86-4.96 (m, 2 H), 5.57-5.78 (m, 1 H);
13C NMR (CDCl3) δ -3.3 (q, 3 C), 21.1 (t), 33.1 (t), 47.4 (t),
114.9 (t), 138.1 (d), 247.0 (s); MS m/ z (rel intensity) 170 (M+,
3), 169 (4), 155 (5), 127 (6), 101 (5), 75 (20), 73 (100); HRMS
calcd for C9H18OSi 170.1127, found 170.1126.
(10:90)) Rf ) 0.5; IR (neat) 2934, 1635, 1457, 1398, 1246, 846,
1
752 cm-1; H NMR (CDCl3) δ 0.10 (s, 18 H), 1.16 (quin, J )
6.8 Hz, 4 H), 1.41 (quin, J ) 6.8 Hz, 4 H), 2.50 (t, J ) 7.2 Hz,
4 H); 13C NMR (CDCl3) δ -3.2 (q, 6 C), 21.8 (t, 2 C), 29.0 (t, 2
C), 48.2 (t, 2 C), 248.0 (s, 2 C); MS m/ z (rel intensity) 286
(M+, 3), 243 (3), 217 (6), 204 (3), 185 (9), 147 (27), 73 (100);
HRMS calcd for C14H30O2Si2 286.1784, found 286.1797.
1-(Tr im eth ylsilyl)-1,5-h exa n ed ion e (33). Compound 32
(160 mg, 0.5 mmol), prepared from 2-(trimethylsilyl)-1,3-
dithiane (2 g, 10.4 mmol) and 5-chloro-2-pentanone ethylene
ketal (1.65 mL, 11 mmol, purchased from Aldrich Co.), was
treated with HgO (216.5 mg, 1 mmol) and BF3‚OEt2 (0.12 mL,
1 mmol) in THF/H2O (6.8 mL/1.2 mL) to give the title
compound 33 (75 mg, 81%) and its ethylene acetal 34 (15 mg,
13%). When the reaction was performed in Me2CO/H2O (6.8
mL/1.2 mL), only 33 (85 mg, 91%) was obtained. 33: An oil;
TLC (EtOAc/hexane (5:95)) Rf ) 0.14; IR (neat) 2957, 2900,
1715, 1641, 1366, 1249, 845 cm-1; 1H NMR (CDCl3) δ 0.16 (s,
9 H), 1.76 (quin, J ) 7.0 Hz, 2 H), 2.09 (s, 3 H), 2.39 (t, J )
7.0 Hz, 2 H), 2.60 (t, J ) 7.0 Hz, 2 H); 13C NMR (CDCl3) δ
-3.2 (q, 3 C), 16.2 (t), 29.8 (q), 42.7 (t), 47.1 (t), 208.5 (s), 247.6
(s); MS m/ z (rel intensity) 186 (M+, 2), 168 (4), 153 (6), 130
(56), 115 (80), 101 (8), 73 (100); HRMS calcd for C9H18O2Si
186.1076, found 186.1094. 34: An oil; TLC (EtOAc/hexane
(5:95)) Rf ) 0.1; IR (neat) 2955, 2882, 1716, 1362, 1246, 1105,
1-(Dip h en ylm eth ylsilyl)-5-h exen on e (21). 2-(4-Pentyl)-
2-(diphenylmethylsilyl)-1,3-dithiane (13, 2.8 g, 7.3 mmol),
prepared from 2-(diphenylmethylsilyl)-1,3-dithiane (2.4 g, 7.5
mmol) and 5-bromo-1-pentene (1.07 mL, 9.12 mmol), was
treated with CAN (11.9 g, 21.9 mmol) to give the title
compound 21 (1.62 g, 76%). An oil; TLC (EtOAc/hexane (2:
98)) Rf ) 0.2; IR (neat) 3064, 3044, 2929, 1636, 1424, 1111,
997 cm-1; 1H NMR (CDCl3) δ 0.73 (s, 3 H), 1.56 (quin, J ) 7.4
Hz, 2 H), 1.92 (q, J ) 7.4 Hz, 2 H), 2.65 (t, J ) 7.4 Hz, 2 H),
4.83-4.93 (m, 2 H), 5.55-5.75 (m, 1 H), 7.33-7.43 (m, 6 H),
7.51-7.59 (m, 4 H); 13C NMR (CDCl3) δ -5.3, 21.2, 33.0, 48.8,
115.0, 128.2, 130.1, 132.8, 135.0, 138.1, 244.3; MS m/ z (rel
intensity) 294 (M+, 8), 293 (41), 197 (100), 137 (20), 84 (20),
49 (51); HRMS calcd for C19H22OSi 294.1442, found 294.1441.
1,5-Bis(tr im eth ylsilyl)-1,5-p en ta n ed ion e (28). To a cold
(0 °C) stirred solution of 2-(trimethylsilyl)-1,3-dithiane (962
mg, 5 mmol) in THF (5 mL) was added dropwise BuLi (3.43
mL of 1.6 M solution in hexane, 5.5 mmol) under Ar. The
mixture was stirred at 0 °C for 20 min, and then 1,3-
dibromopropane (0.25 mL, 2.5 mmol) was added. The result-
ing solution was stirred for another 30 min, and quenched by
addition of aqueous NH4Cl. The volatile components were
removed by rotary evaporator, and the residue was taken up
in EtOAc. The organic phase was washed with brine (2 × 15
mL), dried (Na2SO4), and concentrated on rotary evaporation
to give a crude product of bis-dithiane 24 (1.26 g). To a
mixture of BF3‚OEt2 (1.48 mL, 12 mmol), Celite (1 g), and HgO
(2.5 g, 12 mmol) in 10 mL of THF/H2O (v/v ) 85:15) was added
the crude bis-dithiane 24 in THF (3 mL) dropwise at room
temperature. The mixture was stirred for 20 min and filtered
through a short column containing silica gel and Celite. The
solution was partitioned between ether (20 mL) and water (10
mL), washed with brine (2 × 15 mL), dried (Na2SO4), and
concentrated on rotary evaporation. The residue was purified
by silica gel chromatography with elution of EtOAc/hexane (5:
95) to give the title compound 28 (412 mg, 68%). An oil; TLC
(EtOAc/hexane (5:95)) Rf ) 0.23; IR (neat) 2958, 2901, 1642,
1
840 cm-1; H NMR (CDCl3) δ 0.05 (s, 9 H), 1.54-1.60 (m, 4
H), 2.10 (s, 3 H), 2.40 (t, J ) 6.6 Hz, 2 H), 3.79-3.81 (m, 2 H),
3.91-3.96 (m, 2 H); 13C NMR (CDCl3) δ -3.2 (q, 3 C), 17.7 (t),
29.8 (q), 35.9 (t), 43.9 (t), 65.2 (t, 2 C), 109.0 (s), 208.8 (s); MS
m/ z (rel intensity) 231 (M+ + 1, 30), 215 (9), 201 (10), 157
(100), 145 (31), 99 (60), 73 (65); HRMS calcd for C10H19O3Si
215.1103, found 215.1113.
1-(Tr im eth ylsilyl)-1,5-p en ta n ed ion e (37). A mixture of
2-(trimethylsilyl)-1,3-dithiane (2 equiv) and 4-chlorobutanol (2
equiv) in THF was treated with LDA (3.3 equiv) at -78 °C
gave 35 in quantitative yield. To a suspension of 35 (2.64 g,
10 mmol), 4A molecular sieve (5 g), and Celite (2.64 g) in CH2-
Cl2 (40 mL) was added PCC (4.31 g, 20 mmol) at 0 °C. The
mixture was warmed to room temperature and stirred for 1
h. The reaction was quenched by addition of 30 mL of EtOAc/
hexane (9:1) and filtered. The solvent was removed on rotary
evaporation and purified by silica gel chromatography with
elution of EtOAc/hexane (10:90) to give 4-[1-(trimethylsilyl)-
2,6-dithiacyclohexyl]butanal (36) (1.17 g, 45%). Aldehyde 36
(262 mg, 1 mmol) was treated with HgO (500 mg, 2.3 mmol)
and BF3‚OEt2 (0.12 mL, 1 mmol) to give the title compound
37 (133 mg, 77%) and its dihydropyran derivative 38 (26 mg,
15%). 36: An oil; TLC (EtOAc/hexane (10:90)) Rf ) 0.26; IR
1
1401, 1249, 844, 753 cm-1; H NMR (CDCl3) δ 0.15 (s, 18 H),
1.70 (quin, J ) 6.8 Hz, 2 H), 2.56 (t, J ) 6.8 Hz, 4 H); 13C
NMR (CDCl3) δ -3.3 (q, 6 C), 14.7 (t), 47.3 (t, 2 C), 247.7 (s, 2
C); MS m/ z (rel intensity) 244 (M+, 20), 188 (1),173 (5), 147
(55), 133 (8), 115 (3), 73 (100); HRMS calcd for C11H24O2Si2
244.1315, found 244.1311.
1
(neat) 2950, 2850, 1722, 1248, 844 cm-1; H NMR (CDCl3) δ
0.18 (s, 9 H), 1.79-2.05 (m, 4 H), 2.39-2.52 (m, 4 H), 3.00 (br
t, J ) 14.0 Hz, 2 H), 9.78 (t, J ) 1.2 Hz, 1 H); 13C NMR (CDCl3)
δ -2.5 (q, 3 C), 20.3 (t), 23.3 (t, 2 C), 24.9 (t), 36.7 (t), 38.4 (s),
43.9 (t), 201.9 (s). 37: An oil; TLC (EtOAc/hexane (10:90)) Rf
) 0.17; IR (neat) 2956, 1723, 1640, 1407, 1249, 845, 753 cm-1
;
1,5-Bis(diph en ylm eth ylsilyl)-1,5-pen tan edion e (29). Bis-
dithiane 25, prepared from dithiane 23 (0.44 g, 1.4 mmol) and
1-bromo-3-chloropropane (69 µL, 0.7 mmol), was treated with
HgO (0.75 g, 3.5 mmol), Celite (0.65 g), and BF3‚OEt2 (0.35
mL, 2.8 mmol), by a procedure similar to that for 28, to give
29 (172 mg, 50%) as a light yellow liquid. IR (neat) 3065, 1638,
1H NMR (CDCl3) δ 0.15 (s, 9 H), 1.82 (quin, J ) 7.0 Hz, 2 H),
2.41 (t, J ) 7.0 Hz, 2 H), 2.64 (t, J ) 7.0 Hz, 2 H), 9.70 (t, J )
1.4 Hz, 1 H); 13C NMR (CDCl3) δ -3.2 (q, 3 C), 14.5 (t), 43.1
(t), 46.9 (t), 202.0 (d), 247.1 (s); MS m/ z (rel intensity) 172
(M+, 4), 157 (10), 116 (30), 101 (44), 73 (100), 59 (8), 45 (12);
HRMS calcd for C8H16O2Si 172.0919, found 172.0925. 38: An
oil; TLC (EtOAc/hexane (10:90)) Rf ) 0.22; IR (neat) 3400,
2956, 1622, 1407, 1247, 1221, 1041, 842 cm-1; 1H NMR (CDCl3)
δ 0.06 (s, 9 H), 1.68-2.17 (m, 4 H), 2.97 (d, J ) 4.5 Hz, 1 H),
5.04 (t, J ) 3.9 Hz, 1 H), 5.26 (br d, J ) 2.4 Hz, 1 H); 13C NMR
(CDCl3) δ -2.5 (q, 3 C), 17.2 (t), 27.3 (t), 91.6 (d), 110.6 (d),
156.8 (s); MS m/ z (rel intensity) 172 (M+, 5), 157 (7), 116 (20),
101 (35), 73 (100), 59 (7), 45 (7); HRMS calcd for C8H15O2Si
171.0841, found 171.0856.
1425, 1395, 1252, 1112, 997, 792, 728, 696 cm-1 1H NMR
;
(CDCl3) δ 0.70 (s, 6 H), 1.67 (quintet, J ) 7.0 Hz, 2 H), 2.56 (t,
J ) 7.0 Hz, 4 H), 7.29-7.66 (m, 20 H); 13C NMR (CDCl3) δ
-5.4, 14.8, 48.6, 128.2, 130.1, 132.6, 134.9, 243.8; MS m/ z (rel
intensity) 492 (M+, 70), 356 (6), 333 (15), 255 (21), 197 (100),
117 (11); HRMS calcd for C31H32O2Si2 492.1942, found 492.1942.
1,6-Bis(tr im eth ylsilyl)-1,6-h exan edion e (30). Compound
30 (65% yield) was prepared from bis-dithiane 26 by a
procedure similar to that for 28. An oil; TLC (EtOAc/hexane
(5:95)) Rf ) 0.28; IR (neat) 2956, 2901, 1641, 1402, 1249, 844,
1,3-Bis(2,6-d ith ia cycloh exyl)p r op a n e (39).28 To a mix-
ture of a 50% aqueous solution of glutaric dialdehyde (2.72
mL, 15 mmol), 1,3-propanedithiol (3.0 mL, 30 mmol), and
CHCl3 (40 mL) was added BF3‚OEt2 (1.0 mL, 11 mmol) in
several portions over 2 days. The resulting mixture was
partitioned between ether (100 mL) and water (80 mL). The
organic phase was washed with brine (50 mL), dried (MgSO4),
and concentrated in vacuo. The residue was chromatographed
on silica gel (EtOAc/hexane (4:96)) to give 39 (2.3 g, 55%) as a
752 cm-1 1H NMR (CDCl3) δ 0.15 (s, 18 H), 1.43 (m, 4 H),
;
2.55 (t, J ) 6.8 Hz, 4 H); 13C NMR (CDCl3) δ -3.1 (q, 6 C),
21.7 (t, 2 C), 48.2 (t, 2 C), 247.9 (s, 2 C); MS m/ z (rel intensity)
258 (M+, 15), 217 (2), 157 (15), 147 (28), 129 (3), 101 (2), 73
(100); HRMS calcd for C12H26O2Si2 258.1471, found 258.1479.
1,8-Bis(tr im eth ylsilyl)-1,8-octa n ed ion e (31). Compound
31 (61% yield) was prepared from bis-dithiane 27 by a
procedure similar to that for 28. An oil; TLC (EtOAc/hexane

1802 J . Org. Chem., Vol. 61, No. 5, 1996
Chuang et al.
white solid; mp 100-100.5 °C (lit.28 101.5-102 °C); IR (CH2-
-3.2 (q, 3 C), 21.4 (t), 21.7 (t), 43.7 (t), 47.8 (t), 202.2 (d), 247.5
(s); MS m/ z (rel intensity) 186 (M+, 2), 171 (6), 144 (5), 129
(8), 101 (6), 73 (100), 45 (25); HRMS calcd for C9H18O2Si
186.1077, found 186.1073.
Cl2) 2937, 2901, 1417, 1183, 1008, 906, 697 cm-1 1H NMR
;
(CDCl3) δ 1.65-2.00 (m, 8 H), 2.00-2.18 (m, 2 H), 2.73-2.97
(m, 8 H), 4.01 (br t, J ) 6 Hz, 2 H); 13C NMR (CDCl3) δ 23.7,
25.9, 30.3, 34.7, 47.1.
1-(Dim et h ylp h en ylsilyl)-1,7-h ep t a n ed ion e (48). To a
solution of 41 (2.25 g, 7.3 mmol) in dry THF (8 mL) was added
dropwise at 0 °C a hexane solution of BuLi (1.55 M, 5.2 mL).
The resulting solution was stirred at 0 °C for 10 min followed
by the addition of dimethylphenylchlorosilane (1.34 mL, 8.03
mmol) in one portion. After stirring for another 10 min at 0
°C, the reaction mixture was partitioned between ether (100
mL) and water (80 mL). The organic layer was washed with
brine (50 mL), dried (MgSO4), and concentrated in vacuo. The
residue was mixed with red HgO (6.3 g, 29.2 mmol), THF (30
mL), and water (6 mL), followed by the addition of BF3‚OEt2
(2.69 mL, 22.0 mmol) in one portion. The resulting mixture
was stirred at room temperature for 0.5 h, diluted with ether
(100 mL), and filtered. The filtrate was washed with water
(50 mL), brine (50 mL), dried (MgSO4), and concentrated in
vacuo. The residue was chromatographed on silica gel (EtOAc/
hexane (1:9)) to give 48 (1.04 g, 55%) as a light yellow liquid:
IR (neat) 2934, 1717, 1633, 1423, 1247, 1168, 835, 780, 736,
1,5-Bis(2,6-d ith ia cycloh exyl)p en ta n e (41). Alkylation of
1,3-dithiane (2.4 g, 20 mmol) with 1,5-dibromopentane (1.36
mL, 10 mmol), by a procedure similar to that reported for 28,
gave 41 (2.34 g, 76%) as a white solid. Mp 56-57 °C; IR (CH2-
Cl2) 2935, 2903, 2856, 1455, 1419, 1410, 1271, 1182, 907, 732,
697 cm-1; 1H NMR (CDCl3) δ 1.20-1.33 (quintet, J ) 7.0 Hz,
4 H), 1.65-1.75 (q, J ) 7.0 Hz, 4 H), 1.75-1.90 (m, 2 H), 2.72-
2.90 (m, 8 H), 3.98 (t, J ) 7.0 Hz, 2 H); 13C NMR (CDCl3) δ
25.9, 26.2, 28.7, 30.4, 35.2, 47.4. Anal. Calcd for C13H24S4:
C, 50.61; H, 7.84. Found: C, 50.64; H, 7.75.
1-(Dim et h ylp h en ylsilyl)-1,5-p en t a n ed ion e (46). To a
solution of 39 (1.1 g, 3.9 mmol) in dry THF (5 mL) was added
dropwise at 0 °C a hexane solution of BuLi (1.55 M, 3.0 mL).
The reaction mixture was stirred at 0 °C for 10 min followed
by the addition of dimethylphenylchlorosilane (0.71 mL, 4.3
mmol) in one portion. The resulting mixture was stirred at 0
°C for 10 min and then partitioned between ether (80 mL) and
water (50 mL). The organic layer was washed with brine (50
mL), dried (MgSO4), and concentrated in vacuo to give a liquid.
The liquid was mixed with red HgO (3.37 g, 15.6 mmol), THF
(16 mL), and water (2 mL), followed by the addition of BF3‚
OEt2 (1.2 mL, 10 mmol) in one portion. The resulting mixture
was stirred at room temperature for 20 min, diluted with ether
(50 mL), and filtered through a short pad of silica gel. The
filtrate was washed with water (30 mL), brine (30 mL), dried
(MgSO4), and concentrated in vacuo to give a liquid. The liquid
was chromatographed on silica gel (EtOAc/hexane (2:8) with
the addition of a few drops of Et3N) to afford 46 (0.64 g, 70%)
as a light yellow liquid. IR (neat) 2956, 1717, 1633, 1423, 1247,
1
701 cm-1; H NMR (CDCl3) δ 0.46 (s, 6 H), 1.10-1.25 (m, 2
H), 1.35-1.60 (m, 4 H), 2.31 (td, J ) 7.0, 2.0 Hz, 2 H), 2.54 (t,
J ) 7.0 Hz, 2 H), 7.25-7.45 (m, 3 H), 7.45-7.60 (m, 2 H), 9.67
(t, J ) 2 Hz, 1 H); 13C NMR (CDCl3) δ -4.9, 21.7, 28.5, 43.5,
48.2, 128.1, 129.8, 133.8, 134.4, 202.4, 246.0; MS m/ z (rel
intensity) 262 (M+, 100), 247 (30), 209 (31), 191 (16), 185 (33),
163 (20), 115 (100), 105 (9), 75 (19), 55 (15); HRMS calcd for
C15H22O2Si 262.1389, found 262.1382.
Gen er a l P r oced u r e for Rea ction s of Acyl Sila n es w ith
Sa m a r iu m (II) Iod id e. Samarium metal (0.33 g, 2.1 mmol)
was added under a flow of Ar to an oven-dried round-bottomed
flask containing a magnetic stirring bar. The flask and
samarium were gently flame-dried and cooled under Ar. THF
(20 mL) was added followed by 1,2-diiodoethane (0.5 g, 2
mmol), and the mixture was allowed to stir at room temerature
for 2 h. HMPA (0.35 mL, 2 mmol) was added in appropriate
cases, and the resulting purple solution was allowed to stir
for 30 min. Acyl silane (1 mmol) in THF (20 mL) was added
over a period of 10 min. A proton source (MeOH or t-BuOH,
2 mmol) or alkylating agent (allyl bromide or benzyl bromide,
1.6 mmol) was added in appropriate cases. After complete
addition, the mixture was stirred for 15 min, quenched with
H2O (2 drops), and filtered. The solvent was removed on rotary
evaporation. The residue was passed through a short silica
gel column to remove HMPA, and products were separated
by silica gel chromatography using EtOAc/hexane as eluent.
Gen er a l P r oced u r e for Rea ction s of Acyl Sila n es w ith
Tr ibu tyltin Hyd r id e. To a solution of acyl silane (1.68 mmol)
in deoxygenated benzene (17 mL) was added dropwise at 80
°C over 1 h a solution of Bu3SnH (0.68 mL, 2.52 mmol) and a
catalytic amount of AIBN in deoxygenated benzene (17 mL).
The resulting solution was stirred at 80 °C for another 1 h
and concentrated in vacuo to give an oil. The oil was mixed
with a few drops of Et3N and chromatographed on silica gel
to afford products.
r-(Tr im eth ylsilyl)ben zyl a lcoh ol (49)42 a n d r-P h en yl-
a cetop h en on e (52).43 The reaction of phenyl trimethylsilyl
ketone 2 (178 mg, 1 mmol) with SmI2 in THF at 28 °C for 1 h
gave 49 (113 mg, 63%). The reaction in the presence of HMPA
(0.35 mL, 2 mmol) gave 49 (92 mg, 47%) and R-phenylac-
etophenone (52, 54 mg, 30%). Compound 49-d was obtained
from the reaction of 2 with SmI2 in THF/HMPA/t-BuOD (2
equiv). 49: An oil; TLC (EtOAc/hexane (2:98)) Rf ) 0.2; IR
(neat) 3430, 3061, 2957, 1679, 1445, 1245, 997 cm-1; 1H NMR
(CDCl3) δ 0.00 (s, 9 H), 4.49 (s, 1 H), 7.15-7.28 (m, 5 H); MS
m/ z (rel intensity) 180 (M+, 55), 165 (65), 137 (28), 122 (20),
105 (15), 90 (12), 73 (100). 49-d: 13C NMR (CDCl3) δ 69.9 (J C-D
) 20.0 Hz). MS m/ z (rel intensity) 181 (M+, 16). 52: Solid,
mp 55-56 °C (lit.43 mp 55-56 °C).
1
1110, 836, 779, 735, 700 cm-1; H NMR (CDCl3) δ 0.47 (s, 6
H), 1.76 (quintet, J ) 7.0 Hz, 2 H), 2.31 (td, J ) 7.0, 1.4 Hz,
2 H), 2.60 (t, J ) 7.0 Hz, 2 H), 7.25-7.40 (m, 3 H), 7.45-7.60
(m, 2 H), 9.62 (t, J ) 1.4 Hz, 1 H); 13C NMR (CDCl3) δ -5.0,
14.5, 42.9, 47.2, 128.2, 129.9, 133.9, 134.0, 201.9, 245.2; MS
m/ z (rel intensity) 234 (M+, 8), 193 (91), 178 (13), 163 (21),
152(15), 135 (100), 105 (18), 89 (13); HRMS calcd for C13H18O2-
Si 234.1076, found 234.1079.
1-(Tr im eth ylsilyl)-1,6-h exa n ed ion e (47). Meth od A.
Dithiane 45 (320 mg, 1 mmol), prepared from alkylation of
2-(trimethylsilyl)-1,3-dithiane with 5-bromopentanal ethylene
acetal,29 was stirred with TsOH (22 mg, 0.12 mmol) in acetone
(5 mL) at 25 °C for 24 h. The mixture was partitioned between
Et2O (20 mL) and H2O (10 mL). The organic layer was washed
with brine (15 mL × 2), dried (Na2SO4), and concentrated. The
residue was then treated with HgO (360 mg, 1.66 mmol) and
BF3‚OEt2 (0.2 mL, 1.66 mmol) according to the general
procedure to give 47 (111 mg, 60%).
Meth od B. The crude 2-(4-bromobutyl)-2-(trimethylsilyl)-
1,3-dithiane (40), prepared from alkylation of 2-(trimethylsi-
lyl)-1,3-dithiane (2 g, 10.39 mmol) with 1,4-dibromobutane
(1.24 mL, 10.5 mmol), was dissolved in THF (15 mL) and added
to a solution of 2-lithio-1,3-dithiane (10.8 mmol) in THF (15
mL) at -20 °C under Ar. The reaction was stirred at 0 °C for
20 min and quenched by addition of aqueous NH4Cl. The
organic layer was taken up in EtOAc (60 mL) and washed with
H2O (30 mL × 2), brine (30 mL × 2), dried (Na2SO4), and
concentrated. The residue was treated with HgO (8.26 g, 38.1
mmol) and BF3‚OEt2 (4.69 mL, 38.1 mmol) according to the
general procedure to give 47 (520 mg, 27%).
45: An oil; TLC (EtOAc/hexane (10:90)) Rf ) 0.24; IR (neat)
2944, 1246, 1138, 1036, 944, 910, 842 cm-1; 1H NMR (CDCl3)
δ 0.15 (s, 9 H), 1.44-2.20 (m, 10 H), 2.39 (dt, J ) 14.4, 4.2 Hz,
2 H), 2.98 (br t, J ) 14.4 Hz, 2 H), 3.80-3.94 (m, 4 H), 4.84 (t,
J ) 4.5 Hz, 1 H); 13C NMR (CDCl3) δ -2.5 (q, 3 C), 23.3 (t, 2
C), 24.5 (t), 25.1 (t), 27.5 (t), 33.7 (t), 37.1 (t), 38.6 (s), 64.8 (t,
2 C), 104.5 (d); MS m/ z (rel intensity) 320 (M+, 6), 247 (11),
215 (8), 185 (4), 153 (16), 139 (12), 73 (100); HRMS calcd for
C14H28O2S2Si 320.1300, found 320.13026. 47: An oil; TLC
(EtOAc/hexane (5:95)) Rf ) 0.11; IR (neat) 2952, 2872, 1722,
1-P h en yl-1-(tr im eth ylsilyl)-3-bu ten ol (50). The reaction
of phenyl trimethylsilyl ketone 2 (178 mg, 1 mmol) with SmI2
in THF/HMPA at 25 °C for 15 min, followed by alkylation with
1
1640, 1249, 845, 753 cm-1; H NMR (CDCl3) δ 0.16 (s, 9 H),
1.49-1.57 (m, 4 H), 2.39 (td, J ) 6.8, 1.8 Hz, 2 H), 2.59 (t, J
(42) Wright, A.; West, R. J . Am. Chem. Soc. 1974, 96, 3220
(43) A commercially available compound. Beil. 7 (2), 368.
) 6.8 Hz, 2 H), 9.71 (t, J ) 1.8 Hz, 1 H); 13C NMR (CDCl3) δ

Reactions of Acyl Silanes with SmI2 or Bu3SnH
J . Org. Chem., Vol. 61, No. 5, 1996 1803
allyl bromide (0.09 mL, 1 mmol) for 2 h, gave 50 (184 mg, 84%).
An oil; TLC (EtOAc/hexane (5:95)) Rf ) 0.3; IR (neat) 3512,
(25), 187 (6), 135 (100), 121 (9), 75 (60), 58 (9); HRMS calcd
for C13H20OSi 220.1283, found 220.1268.
1
2951, 1592, 1486, 1437, 1244, 1033 cm-1; H NMR (CDCl3) δ
1-(ter t-Bu tyldim eth ylsilyl)cycloh exan ol (58) an d 6-Br o-
m o-1-(ter t-bu tyld im eth ylsilyl)h exa n ol (59). The reaction
of 6-bromo-1-(tert-butyldimethylsilyl)hexanone (18) (140 mg,
0.47 mmol) with SmI2 in THF at 26 °C for 1 h gave 58 (45 mg,
45%) and 59 (24 mg, 17%). 58: An oil; TLC (EtOAc/hexane
(5:95)) Rf ) 0.28; IR (neat) 3492, 2929, 2854, 1243, 1127, 1005,
830 cm-1; 1H NMR (CDCl3) δ -0.04 (s, 6 H), 0.94 (s, 9 H), 1.01
(br s, 1 H), 1.42-1.78 (m, 10 H); 13C NMR (CDCl3) δ -8.0 (q,
2 C), 17.9 (s), 19.9 (t, 2 C), 26.0 (t), 27.9 (q, 3 C), 34.1 (t, 2 C),
67.3 (s); MS m/ z (rel intensity) 213 (M+ - 1, 5), 185 (15), 149
(22), 129 (36), 111 (51), 97 (65), 57 (100); HRMS calcd for
C12H26OSi 214.1753, found 214.1747. 59: An oil; TLC (EtOAc/
-0.03 (s, 9 H), 1.84 (s, 1 H), 2.49 (dd, J ) 13.0, 9.4 Hz, 1 H),
2.00 (dd, J ) 13.0, 4.6 Hz, 1 H), 5.08-5.18 (m, 2 H), 5.37-
5.51 (m, 1 H), 7.09-7.29 (m, 5 H); 13C NMR (CDCl3) δ -4.1 (q,
3 C), 41.2 (t), 70.4 (s), 124.9 (d, 2 C), 125.1 (d), 127.9 (d, 2 C),
132.7 (d), 145.6 (s); MS m/ z (rel intensity) 220 (M+, 25), 219
(100), 205 (25), 177 (10), 129 (80), 105 (45), 73 (50); HRMS
calcd for C13H20OSi 219.1205, found 219.1195.
1,2-Dip h en yl-1-(tr im eth ylsilyl)eth a n ol (51). The reac-
tion of phenyl trimethylsilyl ketone 2 (90 mg, 0.5 mmol) with
SmI2 in THF/HMPA at 25 °C for 15 min, followed by alkylation
with benzyl bromide (0.1 mL, 0.8 mmol) for 2 h, gave 51 (123
mg, 91%). An oil; TLC (EtOAc/hexane (5:95)) Rf ) 0.15; IR
(neat) 3526, 3062, 2954, 1590, 1486, 1241, 1170 cm-1; 1H NMR
(CDCl3) δ 0.04 (s, 9 H), 1.53 (s, 1 H), 3.16 (d, J ) 13.6 Hz, 1
H), 3.50 (d, J )13.6 Hz, 1 H), 6.91-7.30 (m, 10 H); 13C NMR
(CDCl3) δ -4.0 (q, 3 C), 42.6 (t), 71.7 (s), 124.9 (d, 2 C), 125.0
(d), 126.5 (d), 127.7 (d, 2 C), 128.0 (d, 2 C), 130.5 (d, 2 C), 135.5
(s), 145.5 (s); MS m/ z (rel intensity) 270 (M+, 45), 253 (5), 179
(48), 165 (24), 105 (100), 91 (14), 73 (22); HRMS calcd for
C17H22OSi 270.1440, found 270.1444.
1
hexane (5:95)) Rf ) 0.14; H NMR (CDCl3) δ -0.08 (s, 3 H),
-0.01 (s, 3 H), 0.91 (s, 9 H), 1.35-1.87 (m, 8 H), 3.38 (t, J )
6.8 Hz, 2 H), 3.70 (t, J ) 6.0 Hz, 1 H); MS m/ z (rel intensity)
215 (M+ - Br, 1), 180 (1), 139 (4), 115 (8), 99 (3), 73 (100), 55
(72); HRMS calcd for C12H26BrOSi 295.0915, found 295.0924.
7-Br om o-1-(tr im eth ylsilyl)h ep ta n ol (60). The reaction
of 7-bromo-1-(trimethylsilyl)heptanone (19) (110 mg, 0.41
mmol) with SmI2 in THF at 28 °C for 12 h gave 60 (60 mg,
55%). An oil; TLC (EtOAc/hexane (10:90)) Rf ) 0.33; IR (neat)
3409, 2926, 2853, 1457, 1244, 839, 749 cm-1; 1H NMR (CDCl3)
δ 0.00 (s, 9 H), 1.10-1.55 (m, 9 H), 1.82 (q, J ) 6.8 Hz, 2 H),
3.25 (t, J ) 6.8 Hz, 2 H), 3.37 (t, J ) 6.8 Hz, 2 H); 13C NMR
(CDCl3) δ -3.9 (q, 3 C), 26.5 (t), 28.0 (t), 28.6 (t), 32 (t), 33.3
(t), 33.8 (t), 65.9 (d); MS m/ z (rel intensity) 267 (M+, 12), 229
(2), 183 (1), 133 (15), 117 (50), 95 (25), 73 (100); HRMS calcd
for C10H22BrOSi 267.0603, found 267.0607.
1-(Tr im eth ylsilyl)h exa n ol (53).6 The reaction of 1-(tri-
methylsilyl)-1-hexanone (4) (172 mg, 1 mmol) with SmI2 in
THF at 28 °C for 1 h gave 53 (87 mg, 50%). An oil; TLC
(EtOAc/hexane (5:95)) Rf ) 0.2; 1H NMR (200 MHz, CDCl3) δ
0.01 (s, 9 H), 0.87 (t, J ) 6.6 Hz, 3 H), 1.23-1.33 (m, 6 H),
1.46-1.51 (m, 2 H), 3.27 (t, J ) 6.0 Hz, 1 H).
N-[3-H yd r oxyl-3-(t r im et h ylsilyl)p r op yl]p yr r olid in e-
2,5-d ion e (54). The reaction of N-[3-oxo-3-(trimethylsilyl)-
propyl]pyrroline-2,5-dione (14) (113 mg, 0.5 mmol) with SmI2
in THF at 28 °C for 1 h gave 54 (57 mg, 50%). Solid, mp 78-
79 °C; TLC (EtOAc/hexane (70:30)) Rf ) 0.15; IR (KBr) 3430,
1-(Tr im eth ylsilyl)-5-h exen ol (61) a n d 1-(Tr im eth ylsi-
lyl)-2-m et h ylcyclop en t a n ol (65). The reaction of 1-(tri-
methylsilyl)-5-hexenone (20) (70 mg, 0.4 mmol) with SmI2 in
THF/t-BuOH (0.8 mmol)/HMPA (2 mmol) at 28 °C gave 61 (22
mg, 32%) and 65 (18 mg, 26%). 61: An oil; TLC (EtOAc/
hexane (5:95)) Rf ) 0.2; IR (neat) 3402, 3077, 2953, 1632, 1436,
1
2980, 1750, 1700, 1450, 1240, 880 cm-1; H NMR (CDCl3) δ
-0.22 (s, 9 H), 1.58-1.70 (m, 2 H), 2.72 (s, 4 H), 2.94-3.02
(m, 2 H), 3.66-3.73 (m, 2 H); 13C NMR (CDCl3) δ -4.1 (q, 3
C), 28.1 (t, 2 C), 31.1 (t), 35.6 (t), 60.7 (d), 178.0 (s, 2 C); MS
m/ z (rel intensity) 230 (M+ + 1, 2), 214 (100), 199 (4), 185
(10), 156 (25), 113 (28), 73 (30); HRMS calcd for C9H16NO3Si
214.0899, found 214.0907.
1
1245, 992 cm-1; H NMR (CDCl3) δ 0.02 (s, 9 H), 1.36-1.70
(m, 4 H), 2.01-2.10 (m, 2 H), 3.28 (t, J ) 6.8 Hz, 1 H), 4.90-
5.05 (m, 2 H), 5.70-5.90 (m, 1 H); 13C NMR (CDCl3) δ -3.9 (q,
3 C), 26.0 (t), 32.9 (t), 33.6 (t), 65.9 (d), 114.5 (t), 138.8 (d); MS
m/ z (rel intensity) 172 (M+, 2), 157 (3), 141 (2), 129 (5), 98
(68), 73 (95), 67 (100); HRMS calcd for C9H20OSi 172.1283,
found 172.1283. 65: An oil; TLC (EtOAc/hexane (5:95)) Rf )
3-(2-Br om oph en yl)-1-(tr im eth ylsilyl)pr opan ol (55). The
reaction of 3-(2-bromophenyl)-1-(trimethylsilyl)propanone 15
(110 mg, 0.38 mmol) with SmI2 in THF/HMPA/MeOH at 18
°C for 1 h gave 55 (70 mg, 63%). An oil; TLC (EtOAc/hexane
(10:90)) Rf ) 0.25; IR (neat) 3418, 3058, 1694, 1587, 1560, 1463,
0.25; IR (neat) 3450, 2962, 1457, 1371, 1245, 1205, 930 cm-1
;
1H NMR (CDCl3) δ 0.08 (s, 9 H), 0.87 (d, J ) 6.8 Hz, 3 H),
1.10-2.05 (m, 7 H); 13C NMR (CDCl3) δ -2.4 (q, 3 C), 18.9 (q),
21.4 (t), 32.2 (t), 35.2 (t), 46.2 (d); 13C NMR (acetone-d6) δ -2.0
(q, 3 C), 19.1 (q), 22.0 (t), 32.9 (t), 35.5 (t), 46.8 (d), 77.9 (s);
MS m/ z (rel intensity) 172 (M+, 1), 155 (8), 127 (6), 113 (2),
98 (10), 90 (26), 67 (100); HRMS calcd for C9H19OSi 171.1205,
found 171.1185.
1
1245 cm-1; H NMR (CDCl3) δ 0.03 (s, 9 H), 1.25 (br s, 1 H),
1.75-1.85 (m, 2 H), 2.72-2.80 (m, 1 H), 2.97-3.02 (m, 1 H),
3.31 (dd, J ) 9.3, 4.0 Hz, 1 H), 7.01-7.06 (m, 1 H), 7.21-7.23
(m, 2 H), 7.50 (d, J ) 7.8 Hz, 1 H); 13C NMR (CDCl3) δ -3.9
(q, 3 C), 33.5 (t), 33.7 (t), 65.4 (d), 124.0 (s), 127.4 (d), 127.5
(d), 130.4 (d), 132.7 (d), 141.4 (s); MS m/ z (rel intensity) 287
(M+ - 1, 3), 285 (2), 226 (2), 224 (3), 198 (6), 196 (7), 73 (100);
HRMS calcd for C12H18BrOSi 287.0289, found 287.0303.
3-(2-Br om op h en yl)-1-(d ip h en ylm et h ylsilyl)p r op a n ol
(56). The reaction of 3-(2-bromophenyl)-1-(diphenylmethyl-
silyl)propanone (16) (146 mg, 0.356 mmol) with SmI2 in THF/
HMPA at 28 °C for 1 h gave 56 (75 mg, 52%). An oil; TLC
(EtOAc/hexane (5:95)) Rf ) 0.25; IR (neat) 3442, 3066, 2922,
1-(Dip h en ylm eth ylsilyl)-5-h exen ol (62) a n d 1-(Dip h e-
n ylm eth ylsilyl)-2-m eth ylcyclop en ta n ol (66). The reaction
of 1-(diphenylmethylsilyl)-5-hexenone (21) (100 mg, 0.34 mmol)
with SmI2 in THF/HMPA (2 mmol) for 1 h gave 62 (14 mg,
20%), trans-66 (20 mg, 28%), and cis-66 (20 mg, 28%).
Compound 62-d was obtained from the reaction of 21 with
SmI2 in THF/HMPA/t-BuOD (3 equiv). 62: An oil; TLC
(EtOAc/hexane (5:95)) Rf ) 0.15; IR (neat) 3445, 3070, 2929,
1634, 1250, 1188, 1110 cm-1; 1H NMR (CDCl3) δ 0.60 (s, 3H),
1.13-2.09 (m, 7 H), 3.89 (t, J ) 6.8 Hz, 1 H), 4.89-5.00 (m, 2
H), 5.66-5.87 (m, 1 H) 7.31-7.44 (m, 6 H), 7.56-7.64 (m, 4
H); 13C NMR (CDCl3) δ -6.7 (q), 26.1 (t), 32.8 (t), 33.4 (t), 64.4
(d), 114.5 (t), 127.9 (d, 4 C), 129.5 (d, 2 C), 134.9 (d, 2 C), 135.0
(d, 4 C), 138.7 (d); MS m/ z (rel intensity) 296 (M+, 2), 281 (36),
199 (100), 197 (95), 158 (6), 137 (46), 67 (12); HRMS calcd for
C19H24OSi 296.1596, found 296.1589. 62-d: 13C NMR (CDCl3)
δ 63.8 (J C-D ) 20.0 Hz). MS m/ z (rel intensity) 297 (M+, 4).
trans-66: An oil; TLC (EtOAc/hexane (5:95)) Rf ) 0.2; HPLC
(EtOAc/hexane (2:98)) tR) 10.0 min (Hibar Lichrosorb Si 60
(7 µm) column (25 cm × 1 cm)); IR (neat) 3449, 3068, 2957,
1582, 1250, 1186, 1106 cm-1; 1H NMR (CDCl3) δ 0.62 (s, 3 H),
0.81 (d, J ) 6.8 Hz, 3 H), 1.40-1.96 (m, 7 H) 7.33-7.40 (m, 6
H), 7.65-7.69 (m, 4 H); 13C NMR (CDCl3) δ -5.7 (q), 14.3 (q),
22.3 (t), 32.5 (t), 39.5 (t), 42.2 (d), 127.8 (d, 4 C), 129.3 (d, 2 C),
135.2 (d, 4 C), 135.3 (s, 2 C); MS (rel intensity) m/ z 296 (M+,
1), 281 (20), 214 (8), 197 (100), 158 (50), 137 (70), 120 (20);
1
1422, 1249, 1110, 789 cm-1; H NMR (CDCl3) δ 0.60 (s, 3 H),
1.86-1.98 (m, 2 H), 2.77-2.84 (m, 1 H), 2.99-3.05 (m, 1 H),
3.89-3.93 (m, 1 H), 7.00-7.62 (m, 14 H); 13C NMR (CDCl3) δ
-6.7 (q), 33.6 (t, 2 C), 63.9 (d), 124.5 (s), 127.4 (d), 127.5 (d),
128.0 (d, 4 C), 129.6 (d, 2 C), 130.5 (d), 132.7 (d), 134.5 (s, 2
C), 134.9 (d, 2 C), 135.0 (d, 2 C), 141.2 (s); FAB-MS m/ z (rel
intensity) 412 (M+, 1), 395 (3), 333 (7), 273 (8), 257 (2), 197
(100), 195 (5); HRMS calcd for C21H20BrOSi 397.0446, found
397.0422.
1-(Dim eth ylp h en ylsilyl)cyclop en ta n ol (57). The reac-
tion of 5-bromo-1-(dimethylphenylsilyl)pentanone (17) (180 mg,
0.6 mmol) with SmI2 in THF at 18 °C for 1 h gave 57 (62 mg,
47%). An oil; TLC (EtOAc/hexane (5:95)) Rf ) 0.15; IR (neat)
3422, 2958, 2906, 2853, 1427, 1251, 1111 cm-1 1H NMR
;
(CDCl3) δ 0.33 (s, 6 H), 1.50-1.82 (m, 9 H), 7.32-7.36 (m, 3
H), 7.55-7.59 (m, 2 H); 13C NMR (CDCl3) δ -5.6 (q, 2 C), 23.7
(t, 2 C), 37.6 (t, 2 C), 75.0 (s), 127.8 (d, 2 C), 129.2 (d), 134.3
(d, 2 C), 136.8 (s); MS m/ z (rel intensity) 219 (M+ - 1, 1), 205

1804 J . Org. Chem., Vol. 61, No. 5, 1996
Chuang et al.
HRMS calcd for C19H24OSi 296.1596, found 296.1595. cis-66:
An oil; TLC (EtOAc/hexane (5:95)) Rf ) 0.2; HPLC (EtOAc/
hexane (2:98)) tR ) 11.3 min (Hibar Lichrosorb Si 60 (7 µm)
column (25 cm × 1 cm)); 1H NMR (CDCl3) δ 0.67 (s, 3 H), 0.72
(d, J ) 7.2 Hz, 3 H), 1.18-2.29 (m, 7 H) 7.31-7.38 (m, 6 H),
7.56-7.61 (m, 2 H), 7.70-7.79 (m, 2 H); 13C NMR (CDCl3) δ
-4.1 (q), 19.4 (q), 21.5 (t), 32.1 (t), 36.3 (t), 45.5 (d), 79.3 (s),
127.8 (d, 4 C), 129.3 (d, 2 C), 135.2 (d, 4 C), 135.5 (s, 2 C); MS
m/ z (rel intensity) 296 (M+, 1), 281 (20), 214 (8), 197 (100),
158 (50), 137 (70), 120 (20); HRMS calcd for C19H24OSi
296.1596, found 296.1589.
mg, 12%) and 62 (225 mg, 45%). cis-68: A light yellow liquid;
IR (neat) 2954, 2922, 1584, 1423, 1248, 1115, 1058, 788, 735,
1
698 cm-1; H NMR (CDCl3) δ 0.65 (s, 3 H), 0.65-1.00 (m, 16
H), 1.15-1.95 (m, 20 H), 4.05 (br q, J ) 4.0 Hz, 1 H), 7.25-
7.45 (m, 6 H), 7.55-7.65 (m, 4 H); 13C NMR (CDCl3) δ -2.3,
9.1, 9.2, 13.7, 21.8, 27.4, 29.3, 31.9, 34.5, 44.0, 78.4, 127.7,
129.5, 134.4, 137.4; MS m/ z (rel intensity) 529 (M+ - C4H9,
41), 447 (48), 259 (99), 197 (100), 149 (10), 84 (45), 49 (54);
HRMS calcd for C27H41OSiSn 529.1949; found 529.1946.
trans-68: A light yellow liquid; IR (neat) 2954, 2922, 1584,
1457, 1423, 1248, 1115, 789, 735, 719, 698 cm-1 1H NMR
;
(CDCl3) δ 0.67 (s, 3 H), 0.70-1.00 (m, 16 H), 1.15-2.10 (m, 20
H), 3.74 (br q, J ) 6.0 Hz, 1 H), 7.25-7.45 (m, 6 H), 7.55-
7.65 (m, 4 H); 13C NMR (CDCl3) δ -2.2, 9.2, 13.4, 13.7, 21.2,
27.4, 29.2, 32.3, 33.9, 46.4, 83.6, 127.7, 129.6, 134.4, 137.0; MS
m/ z (rel intensity) 529 (M+ - C4H9, 83), 447 (38), 331 (22),
255 (22), 197 (100), 177 (45), 137 (20), 121 (16), 81 (15); HRMS
calcd for C27H41OSiSn 529.1949, found 529.1957.
4-(Dip h en ylm eth ylsilyl)-1,8-n on a d ien -4-ol (63). The
solution of 21 (100 mg, 0.34 mmol) and allyl bromide (0.035
mL, 0.4 mmol) was treated with SmI2 (1 mmol) in THF/HMPA
at 32 °C for 2 h gave 63 (96 mg, 84%). An oil; TLC (EtOAc/
hexane (5:95)) Rf ) 0.25; IR (neat) 3555, 3069, 2935, 1632,
1423, 1250, 1105 cm-1; 1H NMR (CDCl3) δ 0.66 (s, 3 H), 1.26-
1.40 (m, 3 H), 1.63-1.72 (m, 2 H), 1.92 (q, J ) 6.8 Hz, 2 H),
2.45 (d, J )7.5 Hz, 2 H), 4.86-5.08 (m, 4 H), 5.60-5.79 (m, 2
H), 7.33-7.41 (m, 6 H), 7.70-7.73 (m, 4 H); 13C NMR (CDCl3)
δ -5.0 (q), 22.8 (t), 34.2 (t), 37.4 (t), 42.0 (t), 69.0 (s), 114.5 (t),
118.8 (t), 127.8 (d, 4 C), 129.3 (d, 2 C), 133.4 (d), 135.2 (s, 2 C),
135.4 (d, 4 C), 138.5 (d); MS m/ z (rel intensity) 336 (M+, 18),
321 (40), 307 (25), 295 (40), 245 (28), 197 (100), 137 (80); HRMS
calcd for C22H28OSi 336.1909, found 336.1920.
5-Hyd r oxy-1,5-bis(tr im eth ylsilyl)p en ta n on e (69) a n d
2,6-Bis(tr im eth ylsilyl)-4,5-d ih yd r o-6H-p yr a n (75). The
reaction of 1,5-bis(trimethylsilyl)-1,5-pentanedione 28 (200 mg,
0.81 mmol) with SmI2 (2 mmol) in THF/HMPA at 18 °C for 12
h gave 69 (20 mg, 10%) and 75 (112 mg, 61%). Compound 69
was unstable and converted to 75 on standing. 69: An oil;
1
TLC (EtOAc/hexane (5:95)) Rf ) 0.1; H NMR (CDCl3) δ 0.16
(s, 18 H), 1.65-1.85 (m, 4 H), 2.56 (t, J ) 7.0 Hz, 2 H), 3.71 (t,
J ) 6.6 Hz, 1 H). 75: An oil; TLC (EtOAc/hexane (5:95)) Rf )
2-(Dip h en ylm eth yl)-1-p h en yl-6-h ep ten -2-ol (64). The
solution of 21 (70 mg, 0.238 mmol) and benzyl bromide (0.035
mL, 0.3 mmol) was treated with SmI2 (2 mmol) in THF/HMPA
at 32 °C for 2 h gave 64 (73 mg, 79%). An oil; TLC (EtOAc/
hexane (2:98)) Rf ) 0.15; IR (neat) 3536, 3067, 2934, 1633,
0.25; IR (neat) 2958, 2917, 1619, 1248, 1082, 1038, 1011 cm-1
;
1H NMR (CDCl3) δ 0.01 (s, 9 H), 0.03 (s, 9 H), 1.62-1.78 (m,
2 H), 1.91-2.04 (m, 2 H), 3.40 (dd, J ) 11.1, 3.2 Hz, 1 H),
4.90-4.94 (m, 1 H); 13C NMR (CDCl3) δ -4.1 (q, 3 C), -2.5 (q,
3 C), 21.3 (t), 23.4 (t), 69.1 (d), 109.2 (d), 162.0 (s); MS m/ z
(rel intensity) 228 (M+, 10), 171 (2), 155 (100), 147 (31), 116
(18), 101 (12), 73 (60); HRMS calcd for C11H24OSi2 228.1366,
found 228.1368.
1
1423, 1251, 1107 cm-1; H NMR (CDCl3) δ 0.62 (s, 3 H), 1.23
(s, 1 H), 1.29-1.60 (m, 4 H), 1.83-1.93 (q, J ) 6.8 Hz, 2 H),
2.92 (d, J ) 13.4 Hz, 1 H), 3.12 (d, J )13.4 Hz, 1 H), 4.80-
4.89 (m, 2 H), 5.54-5.71 (m, 1 H), 7.06-7.42 (m, 11 H), 7.74-
7.79 (m, 4 H); 13C NMR (CDCl3) δ -5.2 (q), 23.7 (t), 34.1 (t),
37.6 (t), 42.9 (t), 69.6 (s), 114.4 (t), 126.4 (d), 127.7 (d, 4 C),
128.0 (d, 2 C), 129.2 (d, 2 C), 130.8 (d, 2 C), 135.4 (d, 4 C),
135.5 (d), 136.2 (d, 2 C), 138.3 (d); MS m/ z (rel intensity) 386
(M+, 75), 371 (100), 330 (9), 315 (20), 293 (30), 197 (25), 137
(25).
6-Hyd r oxy-1,6-bis(tr im eth ylsilyl)h exa n on e (70), 1,6-
Bis(tr im eth ylsilyl)-1,6-h exa n ed iol (73), a n d 1-(Tr im eth -
ylsilyl)-2-[(t r im et h ylsilyl)ca r b on yl]cyclop en t a n ol (77).
The reaction of 1,6-bis(trimethylsilyl)-1,6-hexanedione 30 (150
mg, 0.77 mmol) with SmI2 (2 mmol) in THF at 20 °C for 1 h
gave 70 (25 mg, 13%), 73 (20 mg, 9%), and 77 (92 mg, 46%).
70: An oil; TLC (EtOAc/hexane (15:85)) Rf ) 0.28; IR (neat)
3400, 2953, 2857, 1640, 1247, 841, 750 cm-1; 1H NMR (CDCl3)
δ 0.00 (s, 9 H), 0.09 (s, 9 H), 1.25-1.57 (m, 7 H), 2.59 (t, J )
6.6 Hz, 2 H), 3.27 (dd, J ) 9.1, 4.0 Hz, 1 H); 13C NMR (CDCl3)
δ -3.9 (q, 3 C), -3.1 (q, 3 C), 21.6 (t), 26.3 (t), 33.1 (t), 48.2 (t),
65.5 (d), 248.6 (s); MS m/ z (rel intensity) 242 (M+ - 18, 6),
169 (58), 147 (30), 129 (20), 111 (2), 85 (1), 73 (100). 73: Two
isomers, solid; mp 69-73 °C; TLC (EtOAc/hexane (15:85)) Rf
2-(Dip h en ylm eth ylsilyl)-1-[2-(d ip h en ylm eth ylsilyl)-2-
h yd r oxycyclop en tyl]-6-h ep ten -2-ol (67). The reaction of
21 (200 mg, 0.68 mmol) with SmI2 (2 mmol) in THF (27 mL)
gave 62 (26 mg, 13%), 66 (36 mg, 18%; cis/trans ) 46:54) and
67 (76 mg, 38%; diastereomers a /b/c ) 44:44:12). Isomer a
was isolated by column chromatography on silica gel, and pure
isomer b was obtained by HPLC. Isomer a : An oil; TLC
(EtOAc/hexane (10:90)) Rf ) 0.27; IR (neat) 3573, 3066, 2938,
1
1422, 1250, 1106, 699 cm-1; H NMR (CDCl3) δ 0.49 (s, 3 H),
) 0.1; IR (KBr) 3413, 2912, 1242, 1057, 1011, 916, 837 cm-1
;
0.50 (s, 3 H), 0.91-1.84 (m, 15 H), 2.09-2.17 (m, 2 H), 4.78-
4.84 (m, 2 H), 5.50-5.61 (m, 1 H), 7.27-7.39 (m, 12 H), 7.55-
7.64 (m, 8 H); 13C NMR (CDCl3) δ -5.4 (q), -5.2 (q), 22.6 (t),
24.0 (t), 32.7 (t), 34.1 (t), 37.6 (t), 38.3 (t), 38.8 (t), 41.7 (d),
70.1 (s), 77.8 (s), 114.4 (t), 127.7 (d, 4 C), 127.8 (d,4 C), 129.2
(d, 2 C), 129.3 (d, 2 C), 133.9 (s), 135.2 (d, 2 C), 135.3 (d, 4 C),
135.4 (d, 2 C), 135.5 (s, 2 C), 135.7 (s), 138.3 (d); FAB-MS m/ z
(rel intensity) 590 (M+, 0.2), 571 (0.6), 511 (0.6), 375 (10), 333
(18), 196 (100), 137 (72); HRMS calcd for C38H46O2Si2 590.3036,
found 590.3036. Isomer b: An oil; TLC (EtOAc/hexane (10:
90)) Rf ) 0.12; IR (neat) 3576, 3066, 2938, 1422, 1249, 1106,
700 cm-1; 1H NMR (CDCl3) δ 0.38 (s, 3 H), 0.57 (s, 3 H), 0.90-
1.10 (m, 4 H), 1.41-2.00 (m, 13 H), 4.77-4.83 (m, 2 H), 5.50-
5.54 (m, 1 H), 7.26-7.77 (m, 20 H); 13C NMR (CDCl3) δ -5.8
(q), -5.1 (q), 22.4 (t), 23.8 (t), 31.4 (t), 34.2 (t), 37.3 (t), 37.4
(t), 38.6 (t), 42.8 (d), 70.2 (s), 78.4 (s), 114.5 (t), 127.6 (d, 2 C),
127.7 (d, 2 C), 127.8 (d,2 C), 127.9 (d, 2 C), 129.1 (d), 129.2
(d), 129.3 (d), 129.4 (d), 135.1 (d, 2 C), 135.2 (s), 135.3 (d, 4 C),
135.4 (d, 2 C), 135.5 (s, 2 C), 135.7 (s), 138.2 (d); MS m/ z (rel
intensity) 588 (M+ - 2, 6), 545 (8), 503 (8), 451 (10), 375 (22),
197 (24), 137 (100); HRMS calcd for C38H44O2Si2 588.2880,
found 588.2878. Isomer c (mixed with isomer b): TLC (EtOAc/
hexane (10:90)) Rf ) 0.12; 1H NMR (CDCl3) δ 0.42 (s), 0.50 (s).
2-[(Tr ibu tylstan n yl)m eth yl]cyclopen tyl Diph en ylm eth -
yl Eth er (68). The reaction of 21 (494 mg, 1.68 mmol) and
Bu3SnH (0.68 mL, 2.52 mmol) in deoxygenated benzene
according to the general procedure afforded cis-68 (85 mg, 9%),
trans-68 (61 mg, 6%), and a cis/ trans (5:1) mixture of 66 (60
1H NMR (CDCl3) δ 0.00 (s, 18 H), 1.19-1.50 (m, 10 H), 3.26
(t, J ) 6.9 Hz, 2 H); 13C NMR (CDCl3) δ -3.9 (q, 12 C), 26.4 (t,
2 C), 26.7 (t, 2 C), 33.3 (t, 2 C), 33.4 (t, 2 C), 65.8 (d, 2 C), 66.0
(d, 2 C); MS m/ z (rel intensity) 263 (M+ + 1, 15), 245 (8), 226
(12), 171 (10), 147 (22), 136 (18), 73 (100); HRMS calcd for
C12H29O2Si2 261.1706, found 261.1694. 77: An oil; TLC
(EtOAc/hexane (15:85)) Rf ) 0.45; IR (neat) 3400, 2957, 2901,
1620, 1249, 840, 750 cm-1; 1H NMR (CDCl3) δ -0.05 (s, 9 H),
0.18 (s, 9 H), 1.51-1.80 (m, 4 H), 1.94-2.05 (m, 2 H), 3.11
(dd, J ) 10.6, 8.1 Hz, 1 H), 4.13-4.94 (s, 1 H); 13C NMR
(acetone-d6) δ -3.2 (q, 3 C), -2.9 (q, 3 C), 23.6 (t), 28.6 (t),
38.2 (t), 61.0 (d), 77.7 (s), 257.3 (s); MS m/ z (rel intensity) 258
(M+, 10), 230 (2), 217 (4), 157 (10), 147 (16), 117 (2), 73 (100);
HRMS calcd for C12H26O2Si2 258.1471, found 258.1487.
7-Hydr oxy-1,7-bis(tr im eth ylsilyl)octan on e (71) an d 1,8-
Bis(tr im eth ylsilyl)-1,8-h exa n ed iol (74). The reaction of
1,8-bis(trimethylsilyl)-1,8-hexanedione (31) (200 mg, 0.69 mmol)
with SmI2 (2 mmol) in THF for 1 h gave 71 (105 mg, 53%),
and 74 (72 mg, 36%). 71: An oil; TLC (EtOAc/hexane (1:90))
Rf ) 0.25; IR (neat) 3438, 2926, 2853, 1633, 1245, 841, 750
cm-1; 1H NMR (CDCl3) δ 0.00 (s, 9 H), 0.16 (s, 9 H), 1.22-1.50
(m, 11 H), 2.55 (t, J ) 7.2 Hz, 2 H), 3.25 (t, J ) 6.9 Hz, 1 H);
13C NMR (CDCl3) δ -3.9 (q, 3 C), -3.1 (q, 3 C), 22.0 (t), 26.6
(t), 29.3 (t), 29.4 (t), 33.4 (t), 48.4 (t), 65.9 (d), 248.6 (s); MS
m/ z (rel intensity) 243 (M+ - 45, 1), 217 (2), 185 (3), 165 (5),
147 (13), 129 (20), 73 (100); HRMS calcd for C14H31O2Si2
287.1863, found 287.1864. 74: Two isomers, solid; mp 79-

Reactions of Acyl Silanes with SmI2 or Bu3SnH
J . Org. Chem., Vol. 61, No. 5, 1996 1805
84 °C; TLC (EtOAc/hexane (10:90)) Rf ) 0.15; IR (KBr) 3358,
1,12-Bis(t r im et h ylsilyl)-6,7-d ih yd r oxyd od eca n e-1,12-
d ion e (81). To a solution of 1-(trimethylsilyl)-1,6-hexanedione
(47) (180 mg, 0.96 mmol) and t-BuOH (0.19 mL, 2 mmol) in
THF (5 mL) was added 0.1 M solution of SmI2/THF (0.9 mmol/9
mL) at -78 °C under Ar. The resulting solution was warmed
to 32 °C and stirred for 2 h. The reaction was quenched by
addition of Et2O (20 mL) and filtered. The filtrate was
concentrated, and the residue was purified by silica gel
chromatography with elution of EtOAc/hexane (15:85) to give
81 (121 mg, 67%) as a mixture of two diastereomers (3:1). An
oil; TLC (EtOAc/hexane (15:85)) Rf ) 0.22; IR (neat) 3442,
1
2923, 2850, 1372, 1244, 1054, 910 cm-1; H NMR (CDCl3) δ
0.00 (s, 18 H), 1.21-1.47 (m, 14 H), 3.25 (t, J ) 6.6 Hz, 2 H);
13C NMR (CDCl3) δ -3.9 (q, 12 C), 26.7 (t, 2 C), 26.8 (t, 2 C),
29.4 (t, 2 C), 29.5 (t, 2 C), 33.5 (t, 2 C), 65.9 (d, 4 C). FAB-MS
m/ z (rel intensity) 291 (M+ + 1, 20), 273 (10), 225 (30), 154
(8), 136 (28), 129 (12), 73 (100); HRMS calcd for C14H32OSi2
272.1992, found 272.1999.
1,5-Bis(d ip h en ylm eth ylsilyl)-1,5-p en ta n ed iol (72) a n d
2,6-Bis(d ip h en ylm eth ylsilyl)-4,5-d ih yd r o-6H-p yr a n (76).
The reaction of 29 (230 mg, 0.47 mmol) and Bu3SnH (0.25 mL,
0.94 mmol) in deoxygenated benzene (10 mL) according to the
general procedure gave 76 (116 mg, 52%) and a diastereomeric
mixture of 72 (28 mg, 12%). 72: A white solid; mp 103-106
°C; IR (CH2Cl2) 3587, 3067, 2926, 1423, 1363, 1110, 1042, 996,
2938, 1632, 1247, 1167, 1082, 839 cm-1 1H NMR (CDCl3)
;
(major) δ 0.12 (s, 9 H), 0.16 (s, 9 H), 1.23-1.89 (m, 12 H), 2.61
(t, J ) 7.0 Hz, 4 H), 3.60-3.75 (m, 2 H); MS m/ z (rel intensity)
374 (M+, 8), 284 (4), 259 (4), 217 (4), 187 (24), 171 (100), 73
(90); HRMS calcd for C18H38O4Si2 374.2308, found 374.2309.
2-(Dim eth ylp h en ylsilyloxy)cyclop en ta n ol (82) a n d cis-
1,2-Cyclop en ta n ed iol (83). The reaction of 46 (335 mg, 1.43
mmol) and Bu3SnH (0.58 mL, 2.1 mmol) in deoxygenated
benzene (14 mL) according to the general procedure afforded
cis-82 (70 mg, 21%), trans-82 (61 mg, 18%), and cis-83 (47 mg,
32%) which was identical to a commercially available authentic
sample. cis-82: IR (neat) 3546, 3047, 2959, 2901, 1423, 1250.
1116, 1050, 994, 890, 829, 786, 740, 700 cm-1; 1H NMR (CDCl3)
δ 0.41 (s, 3 H), 0.42 (s, 3 H), 1.30-1.45 (m, 1 H), 1.55-1.85
(m, 6 H), 2.63 (d, J ) 4.2 Hz, 1 H), 3.88 (quintet, J ) 4.2 Hz,
1 H), 4.01 (td, J ) 7.0, 4.2 Hz, 1 H), 7.35-7.45 (m, 3 H), 7.55-
7.65 (m, 4 H). 13C NMR (CDCl3) δ -1.4, -1.3, 19.8, 30.7, 31.0,
73.4, 75.4, 127.9, 129.7, 133.3, 137.5. Anal. Calcd for C13H20O2-
Si: C, 66.05; H, 8.53. Found: C, 65.51; H, 8.64. trans-82:
IR (neat) 3367, 2957, 1423, 1249, 1116, 1043, 990, 876, 828,
1
789 cm-1; H NMR (CDCl3) δ 0.57 (s, 6 H,), 1.10-1.70 (m, 8
H), 3.84 (m, 2 H), 7.25-7.40 (m, 12 H), 7.40-7.55 (m, 8 H);
13C NMR (CDCl3) δ -6.8, -6.7, 24.2, 24.4, 32.6, 33.3, 64.2, 64.6,
127.9, 129.5, 129.6, 134.6, 134.9, 135.0. Anal. Calcd for
C31H36O2Si2: C, 74.95; H, 7.30. Found: C, 74.43; H, 7.17. 76:
A light yellow oil; IR (neat) 3064, 3043, 1612, 1424, 1251, 1149,
1112, 1080, 1008, 909, 820 cm-1; 1H NMR (CDCl3) δ 0.56 (s, 3
H), 0.62 (s, 3 H), 1.82-2.20 (m, 4 H), 4.10 (t, J ) 7 Hz, 1 H),
5.10-5.18 (m, 1 H), 7.20-7.49 (m, 12 H), 7.49-7.70 (m, 8 H);
13C NMR (CDCl3) δ -6.6, -5.0, 21.6, 23.6, 68.9, 114.2, 127.6,
127.7, 129.2, 129.3, 134.9, 135.1, 135.2, 135.5, 158.5; MS m/ z
(rel intensity) 476 (M+, 5), 333 (16), 319 (6), 279 (100), 255
(10), 197 (74), 137 (6); HRMS calcd for C31H32OSi2 476.1991,
found 476.1960.
3-Hyd r oxy-3-(tr im eth ylsilyl)cycloh exa n on e (78). The
reaction of 1-(trimethylsilyl)-1,5-hexanedione (33) (80 mg, 0.43
mmol) with SmI2 (0.43 mmol) in THF at 22 °C for 10 min gave
78 (45 mg, 56%). An oil; TLC (EtOAc/hexane (20:80)) Rf )
784, 740, 699 cm-1 1H NMR (CDCl3) δ 0.39 (s, 6 H), 1.30-
;
2.05 (m, 7 H), 3.86-4.02 (m, 2 H), 7.30-7.40 (m, 3 H), 7.35-
7.65 (m, 2 H). 13C NMR (CDCl3) δ -1.4, -1.1, 19.8, 31.1, 31.9,
79.4, 80.2, 127.9, 129.6, 133.4, 138.3. Anal. Calcd for C13H20O2-
Si: C, 66.05; H, 8.53. Found: C, 66.04; H, 8.83.
0.22; IR (neat) 3436, 2948, 1704, 1247, 1111, 940, 839 cm-1
;
1H NMR (CDCl3) δ 0.04 (s, 9 H), 1.07-2.01 (m, 4 H), 2.21-
2.47 (m, 4 H); 13C NMR (acetone-d6) δ -4.5 (q, 3 C), 22.1 (t),
32.1 (t), 41.8 (t), 49.3 (t), 70.3 (s), 210 (s); MS m/ z (rel intensity)
186 (M+, 6), 185 (20), 169 (10), 158 (15), 143 (55), 125 (18), 73
(100); HRMS calcd for C9H18O2Si 186.1076, found 186.1073.
6-(Tr im eth ylsilyl)-3,4,5,6-tetr a h yd r op yr a n -2-on e (79).
The mixture of 1-(trimethylsilyl)-1,5-pentanedione (37) and the
dihydropyran derivative 38 (85 mg, 0.49 mmol; 37/38 ) 5/1)
was treated with SmI2 (0.49 mmol) in THF/MeOH (1 mmol)
at 28 °C for 5 min gave 79 (67 mg, 79%). An oil; TLC (EtOAc/
hexane (20:80)) Rf ) 0.28; IR (KBr) 2954, 2856, 1730, 1249,
1179, 1034, 842 cm-1; 1H NMR (CDCl3) δ 0.06 (s, 9 H), 1.60-
1.94 (m, 4 H), 2.34-2.61 (m, 2 H), 4.04 (dd, J ) 12.1, 3.6 Hz,
1 H); 13C NMR (CDCl3) δ -4.3 (q, 3 C), 20.3 (t), 23.3 (t), 29.6
(t), 75.3 (d), 173.2 (s); MS m/ z (rel intensity) 157 (M+ - 15,
48), 143 (18), 129 (17), 116 (100), 101 (65), 75 (70), 73 (52);
HRMS calcd for C8H16O2Si 172.0920, found 172.0911.
7-Hyd r oxy-7-(d im eth ylp h en ylsilyl)h ep ta n a l (84). The
reaction of 48 (262 mg, 1.00 mmol) and Bu3SnH (0.269 mL,
1.00 mmol) in deoxygenated benzene (5 mL) according to the
general procedure gave 84 (100mg, 38%) as a light yellow
liquid. IR (neat) 3458, 2928, 2854, 1717, 1244, 1110, 814, 701
1
cm-1; H NMR (CDCl3) δ 0.31 (s, 3 H), 0.32, (s, 3 H), 1.05-
1.65 (m, 8 H), 2.37 (td, J ) 9.0, 2.0 Hz, 2 H), 3.47 (t, J ) 7.0
Hz, 1 H), 7.25-7.45 (m, 3 H), 7.45-7.65 (m, 2 H), 9.71 (t, J )
2.0 Hz, 1 H); 13C NMR (CDCl3) δ -5.7, -5.5, 22.0, 26.5, 28.9,
33.1, 43.7, 65.3, 127.9, 129.3, 134,0, 136.6, 202.7; MS m/ z (rel
intensity) 263 (M+ - 1, 1), 249 (M+ - CH3, 0.5), 247 (5), 185
(10), 165 (5), 135 (100), 129 (8), 91 (8), 81 (8), 75 (24), 55 (11);
HRMS calcd for C14H21O2Si 249.1331, found 249.1321.
Ack n ow led gm en t. We thank the National Science
Council of the Republic of China for financial support
(Grants NSC84-2113-M-002-010 and NSC84-2113-M-
002-006). Gratitude is due to Sheng-Yueh Chang, J en-
Sen Pan, and J iuen-Ahn Sieh for providing procedures
or preparations of compounds 6, 15, 16, and 21.
Meth yl 6-Hyd r oxy-6-(tr im eth ylsilyl)h exa n oa te (80).
To a solution of SmI2/THF/MeOH (0.55 mmol/5.5 mL/1 mmol)
was added 1-(trimethylsilyl)-1,6-hexanedione (47) (93 mg, 0.5
mmol) in THF (1 mL) in one portion at 30 °C under Ar. The
reaction was stirred for 30 min and filtered. The filtrate was
concentrated, and the residue was purified by silica gel
chromatography with elution of EtOAc/hexane (15:85) to give
80 (63 mg, 62%). An oil; TLC (EtOAc/hexane (15:85)) Rf ) 0.1;
Su p p or tin g In for m a tion Ava ila ble: NMR spectra (66
pages) of new compounds. This material is contained in
libraries on microfiche, immediately follows this article in the
microfilm version of the journal, and can be ordered from the
ACS; ordering information is given on any current masthead
page.
IR (neat) 3442, 2950, 1733, 1431, 1244, 1199, 838 cm-1 1H
;
NMR (CDCl3) δ 0.00 (s, 9 H), 1.21-1.67 (m, 6 H), 2.29 (t, J )
7.2 Hz, 2 H), 3.27 (t, J ) 7.0 Hz, 1 H), 3.62 (s, 3 H); 13C NMR
(CDCl3) δ -3.9 (q, 3 C), 24.6 (t), 26.2 (t), 32.9 (t), 33.9 (t), 51.4
(q), 65.6 (d), 174.2 (s); MS m/ z (rel intensity) 203 (M+ - 15,
21), 172 (11), 171 (82), 143 (18), 129 (13), 89 (15), 73 (100);
HRMS calcd for C9H19O3Si 203.1104, found 203.1105.
J O951980M