Glycosylidene carbenes. Part 29. Insertion into B-C and Al-C bonds: Glycosylborinates, -boranes, and -alanes

Article abstract of DOI:10.1002/1522-2675(20000705)83:7<1542::AID-HLCA1542>3.0.CO;2-F

Insertion of the glycosylidene carbenes derived from the diazirines 1, 14, and 15 into the B-alkyl bond of the B-alkyl-9-oxa-10- borabicyclo[3.3.2]decanes 5, 6, and 7 yielded the stable glycosylborinates 8/9 (55%, 55:45), 10/11 (31%, 65:35), 12/13 (47%, 60:40), 16/17 (55%, 55:45), 18/19 (47%, 45:55), and 20/21 (31%, 30:70). Crystal-structure analysis of 17 and NOEs of 9 and 19 show that 17, 9, and 19 adopt similar conformations. The glycosylborinates are stable under acidic, basic and thermal conditions. The unprotected glycosylborinate 25 was obtained in 80% by hydrogenolysis of 12. Insertion of the glycosylidene carbene derived from the diazirine 1 into a B- C bond of BEt₃, BBu₃, and BPh₃ led to unstable glycosylboranes that were oxidised to yield the hemiacetals 29 (55%), 31 (45%), and 33 (48%), respectively, besides the glucals 30 (13%), 32 (20%), and 34 (20%), respectively. Insertion of the glycosylidene carbenes derived from 14 and 15 into a B-C bond of BEt₃ led exclusively to hemiacetals; only 15 yielding traces of the glucal 40 besides the hemiacetal 39. The glycosylidene carbene derived from 1 reacted with Al((i)Bu)₃ and AlMe₃ to generate reactive glycosylalanes that were hydrolysed, yielding the C-glycosides 46 (21%) and 49 (30%), respectively, besides the glucals 48 (26%) and 51 (30%); deuteriolysis instead of protonolysis led to the monodeuterio analogues of 46 and 49, respectively, which possess an equatorial ²H-atom at the anomeric center.

Full text of DOI:10.1002/1522-2675(20000705)83:7<1542::AID-HLCA1542>3.0.CO;2-F

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Helvetica Chimica Acta ± Vol. 83 (2000)
Glycosylidene Carbenes
Part 291)
Insertion into BÀC and AlÀC Bonds: Glycosylborinates, -boranes, and -alanes
by Wolfgang Wenger and Andrea Vasella*
Laboratorium für Organische Chemie, ETH-Zentrum, Universitätstrasse 16, CH-8092 Zürich
Insertion of the glycosylidene carbenes derived from the diazirines 1, 14, and 15 into the BÀalkyl bond of
the B-alkyl-9-oxa-10-borabicyclo[3.3.2]decanes 5, 6, and 7 yielded the stable glycosylborinates 8/9 (55%,
55 :45), 10/11 (31%, 65 :35), 12/13 (47%, 60 :40), 16/17 (55%, 55 :45), 18/19 (47%, 45 :55), and 20/21 (31%,
30 :70). Crystal-structure analysis of 17 and NOEs of 9 and 19 show that 17, 9, and 19 adopt similar
conformations. The glycosylborinates are stable under acidic, basic and thermal conditions. The unprotected
glycosylborinate 25 was obtained in 80% by hydrogenolysis of 12. Insertion of the glycosylidene carbene derived
from the diazirine 1 into a BÀC bond of BEt3, BBu3, and BPh3 led to unstable glycosylboranes that were
oxidised to yield the hemiacetals 29 (55%), 31 (45%), and 33 (48%), respectively, besides the glucals 30 (13%),
32 (20%), and 34 (20%), respectively. Insertion of the glycosylidene carbenes derived from 14 and 15 into a
BÀC bond of BEt3 led exclusively to hemiacetals; only 15 yielding traces of the glucal 40 besides the hemiacetal
39. The glycosylidene carbene derived from 1 reacted with Al(iBu)3 and AlMe3 to generate reactive
glycosylalanes that were hydrolysed, yielding the C-glycosides 46 (21%) and 49 (30%), respectively, besides the
glucals 48 (26%) and 51 (30%); deuteriolysis instead of protonolysis led to the monodeuterio analogues of 46
2
and 49, respectively, which possess an equatorial H-atom at the anomeric center.
Introduction. ± Glycosylidene carbenes, generated by thermolysis or photolysis of
diazirines, insert into XÀH bonds to form O-, C-, and N-glycosides [2 ± 6],
glycosylphosphines [7], and glycosylstannanes [8].
We considered that the nucleophilic attack2) of glycosylidene carbenes (e.g., 2) on
triligated B or Al derivatives should lead to tetraligated intermediates, such as the B-
ylide 3 (Scheme 1). These ylides are expected to undergo (axial or equatorial)
migration of a B or Al substituent, respectively, as shown in Scheme 1 for glycosyl-
boranes 4, by analogy to the known migration of a B substituent in tetraligated borates
that possess a vicinal leaving group [12][13]. They should lead to C(1)-substituted
Scheme 1
1
)
)
Part 28: [1].
2
For reviews on the synthesis of C-glycosides including reactions of nucleophilic C-glycosyl donors, see [9 ±
11].

Helvetica Chimica Acta ± Vol. 83 (2000)
1543
B- and Al-glycosides. The structure and reactivity of glycosylboranes and -alanes are of
interest. No anomeric effect is possible for these compounds, and they are expected to
yield geminally disubstituted C-glycosides.
A few examples of the insertion of carbenes and carbenoids into AlÀC bonds are
known for methylene derived from CH2N2 and from a-halo organolithium compounds
[14][15]. Examples of the insertion of substituted and unsubstituted methylene
[12][16][17], an imidazol-2-ylidene carbene [18], dichlorocarbene [19], a phospha-
nylcarbene [20], and methoxycarbene [21] into BÀC bonds of trialkylboranes have
been reported.
We have already briefly reported [1] the insertion of the glycosylidene carbene 2
into the BÀalkyl bond of B-alkyl-9-oxa-10-borabicyclo[3.3.2]decanes that lead to
stable glycosylborinates, and into a BÀC bond of BEt3 to yield unstable
glycosylboranes, which were transformed further by oxidation, elimination, or
rearrangements. We now describe details of these reactions, additional transformations,
and the crystal structure of a glycosylborinate that possesses an equatorial BÀC
bond.
Results and Discussion. ± 1. Synthesis of Stable Glycosylborinates. We selected the
tetrabenzylated gluco-diazirine 1 [22], the manno-isomer 15 [23], and the benzylidene-
protected analogue 14 of 1 as precursors of glycosylidene carbenes (Scheme 2). This
Scheme 2

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Helvetica Chimica Acta ± Vol. 83 (2000)
should allow to determine the effect of the configuration at C(2) and of the annulated
benzylidene ring that is known to increase the life-time of glycosylidene diazirines [23].
The selected diazirines show half-lives at 258 in MeOH of 33 (1 [23]), 23 (15 [23]), and
130 min (14). To obtain stable glycosylboron compounds, we chose the B-alkyl-9-oxa-
10-borabicyclo[3.3.2]decanes (B-alkyl-OBBD) 5 ± 7 as reaction partners, considering
the exceptional stability of these borinates [24][25].
Thermolysis of the diazirines 1, 14, and 15 at 258 in THF in the presence of B-4-
chlorophenethyl-OBBD 5 yielded the anomeric glycosylborinates 8/9 (55%, 55 :45),
16/17 (55%, 55 :45), and 18/19 (47%, 45 :55), which were separated by HPLC.
Similarly, thermolysis of the diazirines 1 and 15 in the presence of 6 yielded the
anomeric glycosylborinates 10/11 (31%, 65 :35) and 20/21 (31%, 30 :70), respectively,
and thermolysis of 1 in the presence of 7 yielded the anomers 12/13 (42%, 60 :40). The
anomers 12/13 and 20/21 were separated by HPLC. All glycosylborinates can be
handled without special precautions and stored at À148 for several months. Except for
17 and 19, all glycosylborinates are oils. Crystals obtained from 17 were suitable for
crystal-structure analysis.
The structure of the glycosylborinates 8 ± 13 and 16 ± 19 was evidenced by 13C-, 11B-, and 1H-NMR
spectroscopy. The 13C-NMR spectra show 5 doublets (65 ± 86 ppm) for CHÀO, one triplet (69 ± 70 ppm) for
CH2ÀO, 6 triplets (38 ± 20 ppm) for aliphatic CH2 groups, and a small broad doublet (20 ± 23 ppm) for a CHÀB
besides the signals for the benzyl, benzylidene, and C(1) alkyl substituents (cf. Table 2). The signals of the
anomeric C-atom are missing as expected for a quarternary CÀB [26]. A broad singlet in the 11B-NMR spectra
at 52 ± 53 ppm is typical for borinates [27]. H-COB resonates as a broad singlet at 4.6 ppm. The 1H-NMR signals
of the glycosylborinates 20/21 correspond to those of 18/19 (Dd < 0.08 ppm; cf. Table 3) except for the signals of
the alkyl substituents at C(1). The coupling constants J(2,3)3) (8.7 ± 9.6 Hz for 8 ± 13 and 16/17, and 2.5 ± 2.8 Hz
for 18 ± 21) and the vicinal coupling constants of the other pyranose-ring H-atoms (8.4 ± 10.0 Hz; cf. Table 3)
4
imply a C1 conformation for the gluco- and manno-configured glycopyranoses, respectively.
The b-d-configuration of 17 was established by crystal-structure analysis (Fig. 1)4).
The glycosylborinate 17 adopts two conformations in the solid state, which differ in the
orientation of the bicyclic system and the aromatic substituents. The endocyclic torsion
angles of the pyranose ring are in the same range for both conformers (Table 1),
indicating a slightly distorted 4C1 conformation. The eight-membered ring is chair-like
in both conformers, avoiding steric interactions of HÀC(3'') and HÀC(7''). Except for
the bond between C(1) and O(5), which is slightly longer (D ˆ 0.03 Š) than in other
geminally disubstituted glycosides [28 ± 30], the bond lengths correspond to standard
values. Due to the almost anti-periplanar orientation of the C(1')ÀC(2') and the
C(1)ÀC(2) bonds in both conformers, one HÀC(1') is oriented towards HÀC(3) and
HÀC(5) (distance: 2.1 ± 2.3 Š; Table 1). The anti-periplanar orientation of the
C(1')ÀC(1) bond and the 4-chlorophenethyl substituent leads to a short distance
between one HÀC(2') and HÀC(5) (2.34/2.66 Š; Table 1). NOEs for the borinates 9
and 19 imply a b-d-configuration and indicate a similar position of the 4-chlorophen-
3
)
To facilitate the comparison, the numbering of the C-atoms of the pyranose rings in the theoretical part is
the same as for hexopyranoses; it does not correspond to the systematic numbering in the Exper. Part.
The crystallographic data have been deposited with the Cambridge Crystallographic Data Centre as
deposition No. CCDC 142256. Copies of the data can be obtained, free of charge, on application to the
CCDC, 12 Union Road, Cambridge CB21EZ, UK (fax: ‡44(1223)336033; e-mail: deposit@ccdc.cam.ac.uk).
4
)

Helvetica Chimica Acta ± Vol. 83 (2000)
1545
Fig. 1. Stereoview of the crystal structure of the glycosylborinate 17 (ORTEP [49] representation)
ethyl substituent in solution as in the solid state of 17: one HÀC(1') signal is enhanced
upon irradiation at C(3) or C(5), and one HÀC(2') signal is enhanced upon irradiation
at C(5), as depicted for 19 (Fig. 2). Analogous NOEs were found for 9 [1]. The smaller
coupling constants (DJ ꢀ 1 Hz; cf. Table 3) between the pyranose-ring H-atoms
indicate a slightly more strongly distorted chair conformation of the b-d-glycosylbori-
nates 9, 11, and 13 in solution, as compared to the a-d-anomers 8, 10, and 12.
The anomeric configuration of 10/11, 12/13, and 20/21 was assigned by comparison
of the 13C- and 1H-NMR data with those of 8/9, 16/17, and 18/19: the axial B substituent
has a deshielding effect on C(5) in 8, 16, and 18 (Dd ˆ 3.7, 4.3, and 5.6 ppm, resp.;
Table 2), as compared to the anomers possessing an equatorial B substituent. This
corresponds to the shift to lower field of the 13C-NMR signal of C(5) of 10, 12, and 20
(Dd ˆ 4.2, 2.8, and 5.6 ppm, resp.; Table 2), indicating the a-d-configuration. The
tetrabenzyl-protected a-d-glycosylborinates 8, 10, and 12 show a shift to lower field for
1
the H-NMR signals of HÀC(5) (3.96, 3.90, and 4.21 ppm, resp.) as compared to the
other signals of the pyranosyl-ring H-atoms (< 3.7 ppm; Table 3). The corresponding b-
d-glycosylborinates 9, 11, and 13 show typically a shift to lower field for the signals of
HÀC(3) (3.91, 3.94, and 3.98 ppm, resp.). The anomeric configuration of the manno-
1
glycosylborinates 20/21 is indicated by the same set of H-NMR signals as for 18/19
(Dd < 0.08 ppm, except for the alkyl substituent at C(1); Table 3).

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Helvetica Chimica Acta ± Vol. 83 (2000)
Table 1. Selected Atom Distances, and Bond and Torsion Angles of the Glycosylborinate 17. Standard deviations
in parentheses.
Bond lengths
Bond angles [8]
Torsion angles [8]
and atom distances [Š]
Conformer A
BÀC(1)
1.601
1.575
1.346
1.533
1.468
BÀC(1)ÀO(5)
BÀC(1)ÀC(2)
OÀBÀC(1)
115.4(5)
113.8(5)
115.4(5)
123.3(5)
C(1)ÀC(2)ÀC(3)ÀC(4)
C(2)ÀC(3)ÀC(4)ÀC(5)
C(3)ÀC(4)ÀC(5)ÀO(5)
C(4)ÀC(5)ÀO(5)ÀC(1)
C(5)ÀO(5)ÀC(1)ÀC(2)
O(5)ÀC(1)ÀC(2)ÀC(3)
C(2)ÀC(1)ÀBÀO
À 53.6(6)
55.0(6)
BÀC(1'')
BÀO
À 60.2(6)
C(1)ÀC(1')
C(1)ÀO(5)
C(1)ÀBÀC(1'')
62.2
À 58.1(6)
54.3(6)
110.5(6)
166.7(5)
173.7(5)
HÀC(3) ´´´ HÀC(1')
HÀC(5) ´´´ HÀC(1')
HÀC(5) ´´´ HÀC(2')
2.15
2.24
2.34
C(2')ÀC(1')ÀC(1)ÀC(2)
C(1)ÀC(1')ÀC(2')ÀC(3')
Conformer B
BÀC(1)
1.613
1.574
1.349
1.524
1.467
BÀC(1)ÀO(5)
BÀC(1)ÀC(2)
OÀBÀC(1)
115.5(5)
114.0(5)
115.5(5)
123.4(5)
C(1)ÀC(2)ÀC(3)ÀC(4)
C(2)ÀC(3)ÀC(4)ÀC(5)
C(3)ÀC(4)ÀC(5)ÀO(5)
C(4)ÀC(5)ÀO(5)ÀC(1)
C(5)ÀO(5)ÀC(1)ÀC(2)
O(5)ÀC(1)ÀC(2)ÀC(3)
C(2)ÀC(1)ÀBÀO
À 51.0(6)
56.5(6)
BÀC(1'')
BÀO
À 63.7(6)
C(1)ÀC(1')
C(1)ÀO(5)
C(1)ÀBÀC(1'')
63.9
À 56.5(6)
49.9(6)
98.5(6)
172.2(5)
À 167.9(5)
HÀC(3) ´´´ HÀC(1')
HÀC(5) ´´´ HÀC(1')
HÀC(5) ´´´ HÀC(2')
2.31
2.14
2.66
C(2')ÀC(1')ÀC(1)ÀC(2)
C(1)ÀC(1')ÀC(2')ÀC(3')
Fig. 2. NOE Signals of the glycosylborinate 19
The formal insertion of the glycosylidene carbenes into the BÀalkyl bond of
B-alkyl-OBBDs shows a low diastereoselectivity, slightly favouring the glucosyl-
borinates 8, 10, 12, 16, and the mannosylborinates 19 and 21; all with the B substituent
cis to the vicinal BnO group. This is rationalised by the intermediate formation of
glycosylborates, such as 22 and 23, respectively (Scheme 3)5), each one reacting via two
conformers, where the migrating group is oriented in the p-plane of the C(1)ÀO bond.
Presumably, the combination of the relative stability and reactivity of the four reactive
conformers leads to the almost equal formation of the diastereoisomeric products.
5
)
Only one of the two diastereoisomeric glycosylborates is depicted in Scheme 3.

Helvetica Chimica Acta ± Vol. 83 (2000)
1547
C(6)
Table 2. Selected 13C-NMR Data of the Glycosylborinates 8 ± 13 and 16 ± 193)
HCÀB
HCOÀB
C(2')
C(1')
C(2)
C(3)
C(4)
C(5)
8
9
23.4
21.3
74.06
74.19
73.90
73.90
73.98
73.68
74.18
72.21
74.67
74.39
29.33
30.19
37.14
28.91
84.90
81.57
84.98
81.88
84.92
82.19
84.24
83.58
79.75c)
81.07c)
85.93
84.42
86.16
84.61
86.60
84.37
83.79
80.96
79.54c)
78.36c)
79.54
79.53
79.64
79.64
79.89
79.51
81.73
80.96
78.22
80.25
76.00
72.27
76.04
71.89
75.44
72.68
67.71
63.43
71.13
65.55
69.93
69.99
69.94
70.07
70.26
70.48
69.91
69.91
69.17
69.68
a
b
b
10
11
12
13
16
17
18
19
)
)
)
)
)
)
)
)
a
b
b
b
24
42.07
40.47
37.29
29.39
34.13
32.11
a
b
)
23.5
21.3
22.6
20.9
29.21
30.37
b
)
)
b
a) Hidden by the noise. b) Not assigned. c) Assignment may be interchanged.
1
Table 3. Selected H-NMR Data of the Glycosylborinates 8 ± 13 and 16 ± 213)
Chemical shifts [ppm]
3J [Hz]
J(2,3)
HÀC(2)
HÀC(3)
HÀC(4)
HÀC(5)
HÀC(6)
H'ÀC(6)
J(3,4)
J(4,5)
8
9
3.50
3.68
3.44
3.63
3.49
3.82
3.59
ꢁ 3.7
4.19
3.97
4.13
3.96
ꢁ 3.7
3.60
3.58
3.96
3.65
3.90
ꢁ 3.7
ꢁ 3.7
9.4
9.0
9.5
9.0
9.6
9.0
8.7
8.7
2.5
2.7
2.5
2.8
9.6
8.7
)
9.6
8.4
9.9
8.8
9.9
9.0
9.9
3.91
3.74
3.73
a
a
a
a
a
10
11
12
13
16
17
18
19
20
21
)
)
)
)
)
)
)
a
a
a
a
3.94
ꢁ 3.7
3.98
3.89
4.01
3.75
4.02
3.75
4.05
)
8.8
9.9
9.0
9.0
8.7
10.0
9.6
9.9
9.6
ꢁ 3.7
3.57
3.63
ꢁ 3.7
4.26
4.36
4.23
4.32
4.21
ꢁ 3.7
3.92
3.45
ꢁ 3.7
4.39
4.31
4.22
4.28
4.17
4.24
ꢁ 3.7
ꢁ 3.7
3.69
ꢁ 3.7
3.83
3.94
3.81
3.90
a
ꢁ 3.7
)
3.27
9.6
9.6
9.6
9.6
3.65
3.20
3.58
a) Not assigned.
Scheme 3

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Helvetica Chimica Acta ± Vol. 83 (2000)
The glycosylborinates are thermally stable and also proved stable to acid and base
treatment. Thus, the anomers 8/9 remained unchanged during heating to reflux in
xylene and remained equally unaffected by boiling in 0.1m HCl in THF, in the presence
of 2 equiv. of Bu4NF in THF, or in the presence of 2 equiv. of NaOEt in toluene.
Similarly, 10/11 remained stable during treatment with 10 equiv. of CF3COOH at 258 in
THF. The glycosylborinates are slowly oxidised by H2O2/NaOH, oxidation of 8/9
requiring 24 h to go to completion, to yield the hemiacetal 24 (Scheme 4). The borinate
9, which possesses an equatorial B substituent, is oxidised noticeably faster than the
corresponding diastereoisomer 8, pointing at a (combined?) effect of a larger steric
hindrance of 8, or a decreased Lewis acidity, as a consequence of the endo-anomeric
effect. Formation of the single hemiacetal 24 from either 8 or 9 denotes the rapid
anomerisation of the hemiacetals. The axial position of the OH group in 24 is indicated
by the deshielding of the pyranosyl CÀH in a 1,3-diaxial relation to the anomeric OH
group (4.00 ppm for HÀC(3) and HÀC(5)), typical for a-d-glucopyranoses.
Scheme 4
With the intention of preparing an unprotected glycosylborinate, we subjected the
cyclopentyl rather than the 4-chlorophenethyl derivatives to hydrogenolysis, to avoid
side reactions as far as possible. Hydrogenolysis of 12 at a pressure of 5 bar H2 in the
presence of prehydrogenated (at 5 bar H2) 10% Pd/C in MeOH/AcOEt yielded the
deprotected glycosylborinate 25 (80%; Scheme 4), while similar treatment of 13 led to
a mixture of polar products. If Pd/C was prehydrogenated at ambient pressure,

Helvetica Chimica Acta ± Vol. 83 (2000)
1549
hydrogenolysis of 12 at 5 bar did not go to completion, and hydrogenolysis of 13
yielded the triol 26 (60%), presumably by hydrogenation of an intermediate glycal. The
ready formation of this glycal evidences a higher propensity of b-d-glucosylborinates
towards elimination.
‡
The structure of 25 is supported by elemental analysis, and signals for [M À H]À (367) and [M ‡ Na] (391)
in the ESI mass spectrum, signals for 5 doublets (79 ± 73 ppm) for CHÀO, a triplet (64 ppm) for CH2ÀO, a
doublet (45 ppm) for CH, 10 triplets (32 ± 23 ppm) for aliphatic CH2, and a small broad doublet (24 ppm) for
CHÀB. A signal for the anomeric C-atom is missing as in the protected glycosylborinate 12. The B-atom is
evidenced by a broad singlet at 55.6 ppm in the 11B-NMR spectrum. The coupling constants J(2,3) (10.0 Hz),
J(3,4) (9.7 Hz), and J(4,5) (10.0 Hz) indicate a 4C1 conformation and the gluco-configuration. The structure of
26 was deduced from the ESI mass spectra (NH4OAc) with peaks for [M ‡ OAc]À (275) in the negative mode
‡
‡
and peaks for [M ‡ Na] (239) and [M ‡ NH4] (234) in the positive mode. C(2)-Atom gives rise to a triplet at
39.52 ppm and C(1) to a doublet at ca. 81 ppm. C(2)H2 gives rise to a ddd (J ˆ 12.8, 5.3, 1.9 Hz) at 1.98 ppm and
to a dt (J ˆ 12.8, 11.5 Hz) at 1.28 ppm. The Jvic value (11.5 Hz) of the signal at 1.28 ppm indicates the axial
position of the corresponding HÀC(2), HÀC(3), and HÀC(1). The 4C1 conformation of the six-membered ring
is confirmed by J(3,4) (8.4 Hz).
2. Glycosylboranes. Thermolysis of 1 in the presence of BEt3 (258, THF), followed
by aqueous or non-aqueous workup, led to a mixture of products dominated by the
hemiacetal 29, and containing traces of the glucal 30 and the azines 39 (see below). This
evidences the intermediate formation of the glycosylboranes 27/28 (Scheme 5), as well
as their high susceptibility to oxidation. Indeed, 13C-NMR signals at 28.9, 25.33, and
17.4 ppm, presumably of CH2ÀC(1) of glycosylboranes 27/286), were detected in the
NMR spectrum of the mixture resulting from thermolysis of 1 in the presence of BEt3
in (D8)THF.
To determine the yield of unstable glycosylboranes, we treated the crude product of
the thermolysis of 1 in the presence of BEt3, BBu3, or BPh3 with alkaline H2O2, and
isolated the a-d-hemiacetals 29, 31 [31], and 33 [32], respectively, in 45 ± 55%, besides
13 ± 20% of the glucals 30, 32 [33], and 347) [33], respectively (Scheme 5 and Table 4,
Entries 1 ± 3). The major side products are the (E,E)- and (Z,Z)-azines 35, resulting
from the reaction of the carbene with the diazirine 1 [23].
Thermolysis of 1 in the presence of the boronate 36 in THF and oxidation with
alkaline H2O2 yielded only the hemiacetal 31 (62%) and no glucal, as expected for the
decreased elimination tendency of boronates [34] (Scheme 5 and Table 4, Entry 4).
Thermolysis of the diazirine 14 in the presence of BEt3 (258, THF), followed by
oxidation with alkaline H2O2 yielded 60% of the hemiacetal 387) (Scheme 5 and
Table 4, Entry 5). The major side product was the (E,E)-configured azine 37, which was
also formed in 35% yield upon thermolysis of 14 in dry MeCN.
6
)
These signals are absent in the NMR spectrum of the crude resulting from a control thermolysis in the
absence of BEt3.
7
)
Formation of the hemiacetal 29 and the glucal 30 upon treatment of the crude with alkaline H2O2 is
evidenced by new signals at 95.5 and 91.4 ppm. The 1H-NMR signals for HÀC(3) and HÀC(5) of 29 (4.04
and 4.02 ppm, resp.), 31 (4.03 and 4.01 ppm, resp.), and 33 (4.10 and 4.21 ppm, resp.) are shifted downfield,
indicating the axial position of the OH groups; similarly, the axial position of the OH group of 38 is
indicated by the chemical shift of HÀC(3) and HÀC(5) (4.07 and 4.04 ppm, resp.), and that of 39 by the
downfield shift of HÀC(7) (4.00 ppm).

1550
Helvetica Chimica Acta ± Vol. 83 (2000)
Scheme 5
The analogous thermolysis of the manno-diazirine 15 in the presence of BEt3,
followed by oxidation with alkaline H2O2, led to a mixture of products that were
difficult to separate. Chromatographic purification led to the manno hemiacetal 397)
(43%) and the gluco-isomer 38 (9%) (Scheme 5 and Table 4, Entry 6); HPLC of the
least polar fraction from the column chromatography yielded a 1:1 mixture of two
1
compounds. One set of H-NMR signals of this mixture evidenced an alkenyl H-atom
(broad d at 4.57 ppm), one PhCH2, one benzylidene, and one Et group (t for 3 H at
0.93 ppm, broad q for 2 H at 2.20 ppm). The similarity of these signals to those of 30
(t at 1.07 ppm, broad q at 2.13 ppm, and a broad d at 4.67 ppm) evidences the glucal 40;
other signals were not assigned (Scheme 5).
The 1,2-elimination of b-alkoxy organoboranes is known, including its configura-
tional aspects [34 ± 39]. There are two reaction pathways, an acid- or base-catalyzed
trans-elimination, and an uncatalyzed cis-elimination [34]. Thus, the glucals 30, 32, and
34 are either formed via a glycosylborane with a trans-relation between the B-atom and
the vicinal BnO substituents (such as 27; Scheme 5), by attack of an external Lewis base

Helvetica Chimica Acta ± Vol. 83 (2000)
1551
Table 4. Yields of Hemiacetals and Glucals after Thermolysis of the Diazirines 1, 14, and 15 in the Presence of
Organoboranes and Oxidation
Entry
Diazirine
Organoborane
Products (yield [%])
1
2
3
4
5
6
1
1
1
1
14
15
BEt3
BBu3
BPh3
36
BEt3
BEt3
29 (55), 30 (13)
31 (45), 32 (20)
33 (48), 34 (20)
31 (62)
38 (60)
39 (43), 38 (9), 40 (< 5)
at the B-atom and trans-elimination, or from an anomer, such as 28, by intramolecular
coordination and cis-elimination [34]. trans-Elimination appears more probable, since
the glucal 30 is only formed upon addition of alkaline H2O2. trans-Elimination of a
glycosylborane of type 27 requires a conformation with the B-atom and vicinal BnO
substituents in axial positions. Indeed, glycosylboranes derived from the conforma-
tionally constrained diazirine 14 failed to give a glucal after oxidation with alkaline
H2O2. They only lead to the hemiacetal 38 (Scheme 5 and Table 4, Entry 5), in
agreement with the requirements for a trans-elimination.
In contrast to the glycosylborinates, glycosylboranes were readily transformed by
acids. Thermolysis of the diazirine 1 in the presence of BEt3 in THF, followed by
treatment with CF3COOH, yielded 46% of the cyclic borinic ester 41, resulting from
the glycosylboranes 27/28 by migration of a second Et group [1] (Scheme 6).
The structure of 41 is evidenced by 13C-NMR signals for 4 Bn groups, 4 doublets (81 ± 74 ppm), a triplet
(71.66 ppm), 2 triplets (26 ± 21 ppm), and 3 quadruplets (10 ± 8 ppm). The signal at 53.1 ppm in the 11B-NMR
spectrum is typical for borinates [27]. HÀC(7) resonates at 4.77 ppm, its chemical shift indicating that the B-
atom is attached to OÀC(7). J(4,5) (4.7 Hz), J(5,6) (4.2 Hz), and J(6,7) (9.5 Hz) values do not correspond to a
single conformation (by Ampac calculation [40]). There are no OH bands in the IR spectrum. The structure of
Scheme 6

1552
Helvetica Chimica Acta ± Vol. 83 (2000)
41 is further supported by its oxidation to the diol 42 and by its transformation to the alkene 43 upon storage in
degassed CDCl3 for several days (Scheme 6).
The structure of 42 and 43 is evidenced by elemental analysis, mass spectrometry, and by the IR and NMR
spectra. The IR spectra show two OH bands (3599 and 3478 cmÀ1) for 42 and one for 43 (3578 cmÀ1). The 1H-
and 13C-NMR spectra show signals of 4 (42) and 3 Bn groups (43), respectively. The OH groups resonate as a
doublet (3.17 ppm) and as a singlet (2.33 ppm) for 42, and as a doublet (2.93 ppm) for 43. The C(3)-atom of 43
gives rise to a singlet at 148.66 ppm and C(4) to a doublet at 120.14 ppm.
3. Reaction of the Carbene 2 with Organoalanes: Glycosylalanes. Thermolysis of 1 in
the presence of Al(iBu)3 in THF at 258, followed by hydrolysis at 258, gave the C-
glycosides 46 (21%) [41] and the glucal 48 (26%) (Scheme 7). AlMe3 reacted similarly,
leading to 49 (30%) [42] and 51 (30%) [43]. Deuterolysis instead of hydrolysis led to
the deuterated C-glycosides 47 and 50, respectively, and the same undeuterated glucals
as before, evidencing the intermediate formation of the glycosylalanes 44 and 45. In
contradistinction to the reaction of 1, thermolysis of the diazirines 14 in the presence of
Al(iBu)3 led to complex mixtures of products.
Scheme 7
Since organoalanes are known to be configurationally stable in etheral solution at
258 [44], and hydrolytic cleavage of AlÀC bonds proceeds with retention of
configuration [45][46], the C-glycosides 46 and 49 most probably arise from trans-
glycosylalanes 44. We assume that both diastereoisomeric glycosylalanes 44/45 were
formed, and that the cis-glycosylalane 45 lead to the glucals 48 and 51 via 1,2-cis-
elimination.8)
Deuteration at C(1) of 47 and 50 is indicated by the disappearance of the signal of
HÀC(1) in the 1H-NMR spectra. A 4C1 conformation and the equatorial position of the
H-atom at C(1) of 46 is indicated by the coupling constants J(1,2) (5.3 Hz), J(2,3)
(9.3 Hz), and J(3,4 or 4,5) (7.8 Hz).
We thank Dr. B. Schweizer for determining the crystal structure, Dr. B. Bernet for helpful discussions and
for checking the Exper. Part, and the Swiss National Science Foundation and F. Hoffmann-La Roche AG, Basel,
for generous financial support.
8
)
A 1,2-elimination of b-alkoxy organoalanes, which could not be isolated, has been proposed for the
reductive cleavage of enol ethers by organoalanes [47][48].

Helvetica Chimica Acta ± Vol. 83 (2000)
1553
Experimental Part
General. Solvents were distilled before use: THF from Na/benzophenone, CH2Cl2 from CaH2. Solvents
were degassed by flushing with a stream of Ar for 2 h. Reactions were run under Ar. Qual. TLC: precoated
silica-gel plates (Merck silica gel 60 F254); detection by spraying with ꢀmostainꢁ (400 ml of 10% aq. H2SO4, 20 g
of (NH4)6Mo7O24 ´ H2O, 0.4 g of Ce(SO4)2) and heating. Flash chromatography (FC): silica gel Merck 60 (0.04 ±
0.063 mm). Prep. HPLC: silica gel, Spherisorb SW 5, 250 Â 20 mm column. Optical rotations: 1-dm cell at 258
and 589 nm. FT-IR: 1 ± 2% soln. in the indicated solvent.
Thermolysis of the Diazirines 1 and 15 in the Presence of Organoboranes and Organoalanes in Degassed
THF. A soln. of the diazirine in dry CH2Cl2 (0.1 ± 0.15m) at À608 was taken into a cooled syringe9) and added in
ca. 12 portions in 2 h to a soln. of the organoborane or the organoalane in THF at 308. Stirring at 308 was
continued until no more diazirine was detectable (1 ± 3 h, depending on the reagents). Detection of diazirines:
applying a sample of the mixture on a silica-gel plate, immersing immediately into a soln. of 4-(4-
nitrobenzyl)pyridine in acetone and heating to 60 ± 808. Pink spots indicate the presence of diazirine.
10-[4,5,6,8-Tetra-O-benzyl-1-C-(4-chlorophenyl)-1,2-dideoxy-a-d-gluco-oct-3-ulo-3,7-pyranosyl]-9-oxa-10-
borabicyclo[3.3.2]decane (8) and 10-[4,5,6,8-Tetra-O-benzyl-1-C-(4-chlorophenyl)-1,2-dideoxy-b-d-gluco-oct-3-
ulo-3,7-pyranosyl]-9-oxa-10-borabicyclo[3.3.2]decane (9). The soln. of thermolysis of the diazirine 1 (77 mg,
0.14 mmol) in the presence of 5 (116 mg, 0.42 mmol) in THF (3 ml) was evaporated at 208. FC (hexane/AcOEt/
CH2Cl2 18 :1:1) and prep. HPLC (hexane/AcOEt 12 :1, 9 ml/min) gave 9 (28 mg, 25%) and 8 (33 mg, 30%) as
colourless oils.
Data of 9: Rf(hexane/AcOEt/CH2Cl2 4 :1:1) 0.36. tR(hexane/AcOEt 12 :1; 9 ml/min) 11.8 min. [a]D25
ˆ
‡51.4 (c ˆ 1.16, CH2Cl2). IR (CH2Cl2): 3032w, 2927m, 2963m, 1604w, 1493m, 1453m, 1420m, 1364m, 1092s,
1027s. 1H-NMR (300 MHz, CDCl3): 7.62 ± 7.11 (m, 24 arom. H); 4.87 (d, J ˆ 10.6, PhCH); 4.85 (d, J ˆ 10.9,
PhCH); 4.83 (d, J ˆ 10.9, PhCH); 4.77 (d, J ˆ 10.9, PhCH); 4.72 ± 4.68 (m, HCOB); 4.71 (d, J ˆ 12.1, PhCH);
4.68 (d, J ˆ 10.9, PhCH); 4.66 (d, J ˆ 10.9, PhCH); 4.64 (d, J ˆ 12.1, PhCH); 3.91 (t, J ˆ 8.7, HÀC(5)); 3.74
(dd, J ˆ 11.2, 4.0, HÀC(8)); 3.73 (dd, J ˆ 11.2, 1.9, H'ÀC(8)); 3.68 (d, J ˆ 9.0, irrad. at. 3.91 ! d, J ꢀ 4, HÀC(4));
3.67 ± 3.63 (m, HÀC(7)); 3.58 (t, J ˆ 8.4, irrad. at 3.91 ! dd, J ꢀ 9, 3, HÀC(6)); 2.65 ± 2.56 (m, irrad. at 3.64 !
NOE of 1%, 2 HÀC(1)); 2.37 ± 2.27 (m, irrad. at 2.6 ! d, J ꢀ 10, HÀC(2)); 2.21 (br. s, irrad. at 3.68 ! NOE of
1%, HCB); 2.01 ± 1.91 (m, irrad. at 2.6 ! d, J ꢀ 10, irrad. at 3.9 ! NOE of 2%; irrad. at 3.64 ! NOE of 3%,
H'ÀC(2)); 2.01 ± 1.46 (m, 12 H). 11B-NMR (160 MHz, CDCl3): 52.02 (br. s). 13C-NMR (75 MHz, CDCl3,
assignment based on 1H/13C-COSY spectrum): 142.03 (s); 139.00 (2s); 138.69, 138.29, 131.12 (3s); 129.79 ± 127.12
(several d); 84.42 (d, C(5)); 81.57 (d, C(4)); 79.53 (d, C(6)); 75.60, 75.13, 74.73 (3t, 3 PhCH2); 74.19 (d, HCOB);
73.51 (t, PhCH2); 72.24 (d, C(7)); 69.99 (t, C(8)); 32.41, 30.63 (2t); 30.19 (t, C(1)); 28.91 (t, C(2)); 27.54, 25.63,
‡
22.89, 21.91 (4t); 21.3 (small br. d, BCH); signal for C(3) missing. FAB-MS (3-NOBA): 821 (<1, [M ‡ Na] ),
‡
‡
799 (<1, [M ‡ H] ), 599 (38), 553 (43, [M À OBn À C8H14BO] ), 447 (44), 181 (100). Anal. calc. for
C50H56BClO6 (799.25): C 75.14, H 7.06; found: C 74.87, H 7.23.
Data of 8: Rf(hexane/AcOEt/CH2Cl2 10 :1:1) 0.32. tR(hexane/AcOEt 12 :1; 9 ml/min) 18.4 min. [a]D25
ˆ
‡12.0 (c ˆ 0.65, CH2Cl2). IR (CH2Cl2): 3032w, 2927m, 1492m, 1453m, 1418w, 1364m, 1093s, 1027m, 1015m.
1H-NMR (300 MHz, CDCl3): 7.38 ± 6.99 (m, 24 arom. H); 4.98 (d, J ˆ 11.8, PhCH); 4.85 (d, J ˆ 10.9, PhCH);
4.84 (s, PhCH2); 4.72 ± 4.68 (m, HCOB); 4.70 (d, J ˆ 11.8, PhCH); 4.68 (d, J ˆ 12.1; PhCH); 4.62 (d, J ˆ 10.9,
PhCH); 4.60 (d, J ˆ 12.1, PhCH); 3.96 (dt, J ꢀ 9, 4, HÀC(7)); 3.78 ± 3.70 (m, HÀC(5), 2 HÀC(8)); 3.60 (t, J ˆ
9.6, irrad. at 3.96 ! d, J ꢀ 9, HÀC(6)); 3.50 (d, J ˆ 9.4, HÀC(4)); 2.74 ± 2.67 (m, 2 HÀC(1)); 2.25 (br. s, irrad. at
3.96 ! NOE of < 1%, HCB); 2.05 ± 1.95 (m, irrad. at 2.70 ! d, J ꢀ 12, HÀC(2)); 1.99 ± 1.26 (m, 13 H). 11B-
NMR (160 MHz, CDCl3): 53.8 (br. s). 13C-NMR (75 MHz, CDCl3, assignment based on 1H/13C-COSY
spectrum): 141.75 (s); 139.26 (2s); 138.2, 137.8, 133.6 (3s); 129.9 ± 127.14 (several d); 85.93 (d, C(5)); 84.90
(d, C(4)); 79.54 (d, C(6)); 76.00 (d, C(7)); 75.37, 75.09, 74.80 (3t, 3 PhCH2); 74.06 (d, CHOB); 73.22 (t, PhCH2);
69.93 (t, C(8)); 37.14 (t, C(2)); 31.82, 30.91 (2t); 29.33 (t, C(1)); 26.79, 25.77 (2t); 23.4 (small br. d, BCH); 22.48,
‡
‡
21.92 (2t); signal for C(3) missing. FAB-MS (3-NOBA): 821 (<1, [M ‡ Na] ), 799 (<1, [M ‡ H] ), 553 (43,
‡
[M À OBn À C8H14BO] ), 461 (28), 401 (41), 325 (60), 281 (87), 181 (100). Anal. calc. for C50H56BClO6
(799.25): C 75.14, H 7.06; found: C 75.47, H 7.23.
10-(8,9,10,12-Tetra-O-benzyl-1,2,3,4,5,6-hexadeoxy-a-d-gluco-dodec-7-ulo-7,11-pyranosyl)-9-oxa-10-bora-
bicyclo[3.3.2]decane (10) and 10-(8,9,10,12-Tetra-O-benzyl-1,2,3,4,5,6-hexadeoxy-b-d-gluco-dodec-7-ulo-7,11-
pyranosyl)-9-oxa-10-borabicyclo[3.3.2]decane (11). The soln. of the thermolysis of the diazirine 1 (48 mg,
9
)
The syringe containing the diazirine soln. was placed in a small container that was charged with dry-ice
during the addition.

1554
Helvetica Chimica Acta ± Vol. 83 (2000)
0.09 mmol) in the presence of 6 (160 mg, 0.72 mmol) in THF (3 ml) was evaporated at 208. FC (hexane/AcOEt/
CH2Cl2 25 :1 :1) gave 10/11 65 :35 (20 mg, 31%) as a colourless oil. Rf(hexane/AcOEt/CH2Cl2 4 :1:1) 0.73.
1H-NMR (500 MHz, CDCl3; 10/11 65 :35): 7.36 ± 7.21 (m, 20 arom. H); 4.94 (d, J ˆ 11.7, 0.65 H), 4.91 (d, J ˆ
10.8, 0.35 H) (PhCH); 4.86 ± 4.79 (m, 3 H); 4.71 ± 4.62 (m, 3.7 H), 4.60 (d, J ˆ 10.9, 0.65 H), 4.59 (d, J ˆ 12.2,
0.65 H) (PhCH); 3.94 (t, J ˆ 8.8, 0.35 H, HÀC(9)); 3.90 (ddd, J ˆ 9.9, 3.8, 2.3, 0.65 H, HÀC(11)); 3.79 ± 3.68
(m, 2.7 H); 3.63 (d, J ˆ 9.0, 0.35 H, HÀC(8)); 3.58 ± 3.53 (m, 1.3 H); 3.44 (d, J ˆ 9.5, 0.65 H, HÀC(8)); 2.25 ±
2.23 (m, 0.65 H); 2.19 ± 2.17 (m, 0.35 H); 1.88 ± 1.22 (m, 22 H); 0.9 ± 0.86 (m, 3 H). 11B-NMR (160 MHz,
CDCl3): 52.6 (br. s). 13C-NMR (75 MHz, CDCl3): 139.36, 139.22, 139.09, 138.71, 138.45 (5s); 128.44 ± 127.01
(several d); 86.16 (d, C(9) (a)); 84.98 (d, C(8) (a)); 84.61 (d, C(9) (b)); 81.88 (d, C(8) (b)); 79.64 (d, C(10));
76.04 (d, C(11) (a)); 75.58, 75.28, 75.13, 75.05, 74.81 (5t, 5 PhCH); 73.90 (d, CHOB); 73.50, 73.17 (2t, 2 PhCH);
71.89 (d, C(11) (b)); 70.07 (t, C(12) (b)); 69.94 (t, C(12) (a)); 35.19, 32.28, 31.94, 31.00, 30.76, 30.22, 30.13, 26.91,
‡
25.92, 25.63, 23.59, 22.67, 22.01 (13t); 14.09 (q, Me). FAB-MS (3-NOBA): 767 (<1, [M ‡ Na] ), 745 (<1, [M ‡
‡
‡
H] ), 545 (5), 499 (22, [M À OBn À C8H14BO] ), 358 (100). Anal. calc. for C48H61BO6 (744.82): C 77.41, H 8.25;
found: C 77.35, H 8.27.
10-(2,3,4,6-Tetra-O-benzyl-1-C-cyclopentyl-a-d-glucopyranosyl)-9-oxa-10-borabicyclo[3.3.2]decane (12)
and 10-(2,3,4,6-Tetra-O-benzyl-1-C-cyclopentyl-b-d-glucopyranosyl)-9-oxa-10-borabicyclo[3.3.2]decane (13).
The soln. of the thermolysis of the diazirine 1 (97 mg, 0.18 mmol) in the presence of 7 (370 mg, 1.8 mmol) in
THF (5.5 ml) was evaporated at 208. FC (hexane/AcOEt/CH2Cl2 18 :1:1) and prep. HPLC (hexane/AcOEt
12 :1, 9 ml/min) gave 13 (22 mg, 17%) and 12 (33 mg, 25%) as colourless oils.
Data of 13: Rf(hexane/AcOEt/CH2Cl2 10 :1:1) 0.38. tR(hexane/AcOEt 12 :1; 9 ml/min) 9.6 min. 1H-NMR
(300 MHz, CDCl3): 7.35 ± 7.23 (m, 20 arom. H); 4.89 ± 4.77 (m, 5 PhCH); 4.69 (d, J ˆ 12.1, PhCH); 4.64 (d, J ˆ
11.2, PhCH); 4.62 ± 4.58 (m, HCOB); 4.60 (d, J ˆ 12.4, PhCH); 3.98 (t, J ˆ 8.7, irrad. at 3.57 ! d, J ꢀ 9,
HÀC(3)); 3.82 (d, J ˆ 9.0, irrad. at 3.98 ! m, HÀC(2)); 3.78 ± 3.69 (m, 3 H); 3.57 (t, J ˆ 9.0, irrad. at 3.98 !
d, J ꢀ 9, HÀC(4)); 2.51 ± 2.45 (m, 1 H); 2.16 ± 2.10 (m, 1 H); 2.01 ± 1.41 (m, 20 H). 13C-NMR (75 MHz, CDCl3):
139.83, 139.20, 138.95, 138.60 (4s); 128.37 ± 127.01 (several d); 84.37 (d, C(3)); 82.91 (d, C(2)); 79.51 (d, C(4));
75.25 (t, PhCH2); 74.73 (t, 2 PhCH2); 73.68 (d, CHOB); 73.50 (t, PhCH2); 72.68 (d, C(5)); 70.48 (t, C(6)); 40.47
(d, C(1')); 32.13, 31.03, 29.92, 29.38 (4t); 26.46 (3t); 24.95, 22.58, 22.06 (3t); signals of HCB and of C(1) missing.
‡
‡
FAB-MS (3-NOBA): 751 (<1, [M ‡ Na] ), 729 (<1, [M ‡ H] ), 529 (23), 483 (67), 377 (92).
Data of 12: Rf(hexane/AcOEt/CH2Cl2 10 :1:1) 0.36. tR(hexane/AcOEt 12 :1; 9 ml/min) 11.4 min. 1H-NMR
(300 MHz, CDCl3): 7.38 ± 7.25 (m, 20 H); 4.98 (d, J ˆ 11.5, PhCH); 4.89 (d, J ˆ 10.9, PhCH); 4.85 (s, PhCH2);
4.76 (d, J ˆ 11.5, PhCH); 4.68 (d, J ˆ 12.1, PhCH); 4.68 ± 4.65 (m, HCOB); 4.66 (d, J ˆ 10.5, PhCH); 4.63 (d, J ˆ
11.9, PhCH); 4.21 (dt, J ꢀ 10, 3, HÀC(5)); 3.75 ± 3.66 (m, 3 H); 3.49 (d, J ˆ 9.6, HÀC(2)); 3.45 (t, J ˆ 9.9, irrad.
at 4.21 ! d, J ꢀ 10, HÀC(4)); 2.52 ± 2.47 (m, 1 H); 2.21 (br. s, 1 H); 1.93 ± 1.27 (m, 20 H). 13C-NMR (75 MHz,
CDCl3): 139.44, 139.36, 138.80, 138.69 (4s); 128.32 ± 127.01 (several d); 86.60 (d, C(3)); 84.92 (d, C(2)); 79.89
(d, C(4)); 75.44 (d, C(5)); 75.33, 74.98 (2t, 3 PhCH2); 73.89 (d, CHOB); 73.18 (t, PhCH2); 70.26 (t, C(6)); 42.07
(d, C(1')); 32.39, 30.44, 28.16, 27.47, 26.83, 26.57, 26.08, 25.76 (8t); 24 (small br. s, HCB); 23.01, 21.75 (2t); signal
‡
‡
of C(1) missing. FAB-MS (3-NOBA): 751 (<1, [M ‡ Na] ), 729 (<1, [M ‡ H] ), 529 (23), 483 (67), 377 (92).
10-[4,5-Di-O-benzyl-6,8-O-benzylidene-1-C-(4-chlorophenyl)-1,2-dideoxy-a-d-gluco-oct-3-ulo-3,7-pyrano-
syl]-9-oxa-10-borabicyclo[3.3.2]decane (16) and 10-[4,5-Di-O-benzyl-6,8-O-benzylidene-1-C-(4-chlorophenyl)-
1,2-dideoxy-b-d-gluco-oct-3-ulo-3,7-pyranosyl]-9-oxa-10-borabicyclo[3.3.2]decane (17). A soln. of 14 (50 mg,
0.11 mmol) in dry CH2Cl2 (0.6 ml) was treated with a soln. of 5 (155 mg, 0.56 mmol) in dry THF (3 ml), stirred
at 308 for 6 h (TLC: complete consumption of 14), and evaporated at 08. FC (hexane/AcOEt/CH2Cl2 25 :1 :1)
and prep. HPLC (hexane/AcOEt 22 :1, 9 ml/min) gave 16 (23 mg, 30%) as a colourless oil and 17 (19 mg, 25%)
as a crystalline solid.
Data of 16: Rf(hexane/AcOEt/CH2Cl2 10 :1 :1) 0.36. tR(hexane/AcOEt 22 :1, 9 ml/min) 24.4 min. [a]D25
ˆ
1
À28.8 (c ˆ 0.29, CH2Cl2). H-NMR (300 MHz, CDCl3): 7.56 ± 7.52 (m, 2 H); 7.43 ± 7.18 (m, 15 arom. H); 7.02 ±
6.98 (m, 2 arom. H); 5.60 (s, PhCH); 5.06 (d, J ˆ 11.8, PhCH); 4.97 (d, J ˆ 11.2, PhCH); 4.82 (d, J ˆ 11.5,
PhCH); 4.72 ± 4.68 (m, HCOB); 4.70 (d, J ˆ 11.8, PhCH); 4.39 (dd, J ˆ 9.9, 4.7, HeqÀC(8)); 3.92 (td, J ˆ 9.9, 4.9,
irrad. at 4.39 ! t, J ꢀ 9, HÀC(7)); 3.89 (t, J ˆ 9.0, HÀC(5)); 3.69 (t, J ˆ 9.9, irrad. at 4.39 ! d, J ꢀ 9, HaxÀC(8));
3.63 (t, J ˆ 9.0, HÀC(6)); 3.59 (d, J ˆ 8.7, HÀC(4)); 2.63 (br. t, J ꢀ 9, 1 H); 2.16 ± 1.26 (m, 15 H). 13C-NMR
(75 MHz, CDCl3): 141.27, 138.79, 138.55, 137.77, 131.35 (5s); 129.76 ± 126.01 (several d); 100.99 (d, PhCH); 84.24
(d, C(4)); 83.79 (d, C(5)); 81.73 (d, C(6)); 75.70, 74.62 (2t, 2 PhCH2)); 74.18 (d, HCOB); 69.91 (t, C(8)); 67.71
(d, HÀC(7)); 37.29 (t, C(2)); 31.85, 30.93 (2t); 29.21 (t, C(1)); 26.86, 25.55 (2t); 23.5 (small br. d, HCB); 22.54,
‡
22.03 (2t); signal for C(3) missing. FAB-MS (3-NOBA): 707 (100, M ), 601 (30). Anal. calc. for C43H48BClO6
(707.11): C 73.04, H 6.84; found: C 73.12, H 6.87.

Helvetica Chimica Acta ± Vol. 83 (2000)
1555
Data of 17: Rf(hexane/AcOEt/CH2Cl2 10 :1:1) 0.36. tR(hexane/AcOEt 22 :1, 9 ml/min) 25.4 min. M.p. 1208.
1
[a]2D5 ˆ ‡50.0 (c ˆ 0.10, CH2Cl2). H-NMR (300 MHz, CDCl3): 7.54 ± 7.50 (m, 2 arom. H); 7.42 ± 7.22 (m, 15 ar-
om. H); 7.18 ± 7.15 (m, 2 arom. H); 5.60 (s, PhCH); 4.96 (d, J ˆ 10.9, PhCH); 4.95 (d, J ˆ 11.2, PhCH); 4.71 ±
4.68 (m, HCOB); 4.69 (d, J ˆ 10.9, PhCH); 4.65 (d, J ˆ 11.2, PhCH); 4.31 (dd, J ˆ 9.6, 3.4, HeqÀC(8)); 4.01
(t, J ˆ 8.7, HÀC(5)); 3.78 ± 3.64 (m, 4 H); 2.60 (td, J ˆ 13.7, 5.3, 1 H); 2.52 (td, J ˆ 12.8, 5.3, 1 H); 2.38 (td, J ˆ
13.7, 5.3, 1 H); 2.10 ± 1.40 (m, 14 H). 13C-NMR (75 MHz, CDCl3): 141.72, 139.05, 138.65, 137.61, 131.28 (5s);
129.78 ± 125.96 (several d); 101.05 (d, PhCH); 83.58 (d, C(4)); 80.96 (d, C(5), C(6)); 75.31, 75.12 (2t, 2 PhCH2);
72.21 (d, HCOB); 69.91 (t, C(8)); 63.43 (d, C(7)); 32.22, 30.75 (2t); 30.37 (t, C(1)); 29.39 (t, C(2)); 27.40, 25.59,
‡
22.76, 21.93 (4t); 21.3 (small br. d, HCB); signal for C(3) missing. FAB-MS (3-NOBA): 730 (12, [M ‡ Na] ), 707
‡
(52, M ), 461 (70), 355 (100). Anal. calc. for C43H48BClO6 (707.11): C 73.04, H 6.84; found: C 73.5, H 6.90.
X-Ray Crystal-Structure Analysis of 17. Crystals were obtained by isothermic evaporation of MeOH from a
soln. of 17 in MeOH. C43H48BClO6 (707.07). Orthorhombic. P212121. a ˆ 13.358(5) Š, b ˆ 13.225(2) Š, c ˆ
43.246(10) Š, Vˆ 7640(4) Š3, Z ˆ 8, Dcalc. ˆ 1.229 Mg/m3. From a crystal of size 0.20  0.15  0.10 mm 7506
reflexions were measured on an Enraf Nonius CAD-4 Diffractometer with CuKa radiation (graphite
monochromator, l ˆ 1.54184 Š) at 103(2) K. Part of the structure was solved by direct methods with SIR97 [50],
the remaining non-H-atoms were found from a difference Fourier map with SIR97 [50]. The non-H-atoms were
refined anisotropically with SHELXL97 [51]. H-Atoms were calculated at idealyzed positions and included in
the structure factor calculation with fixed isotropic displacement parameters. The structure converged at an R
value of 0.0530 using 5038 reflections with I > 3s(I).
10-[4,5-Di-O-benzyl-6,8-O-benzylidene-1-C-(4-chlorophenyl)-1,2-dideoxy-a-d-manno-oct-3-ulo-3,7-pyra-
nosyl]-9-oxa-10-borabicyclo[3.3.2]decane (18) and 10-[4,5-Di-O-benzyl-6,8-O-benzylidene-1-C-(4-chlorophen-
yl)-1,2-dideoxy-b-d-manno-oct-3-ulo-3,7-pyranosyl]-9-oxa-10-borabicyclo[3.3.2]decane (19). The soln. result-
ing from the thermolysis of the diazirine 15 (40 mg, 0.087 mmol) in the presence of 5 (100 mg, 0.37 mmol) in
degassed THF (5 ml) was evaporated at 208. FC (hexane/AcOEt/CH2Cl2 20 :1:1) and prep. HPLC (hexane/
AcOEt 12 :1, 9 ml/min) gave 18 (13 mg, 21%) as a colourless oil and 19 (16 mg, 26%) as a white solid.
Data of 18: Rf(hexane/AcOEt/CH2Cl2 4 :1:1) 0.62. tR(hexane/AcOEt 12 :1, 9 ml/min) 14.4 min. [a]D25
ˆ
‡24.5 (c ˆ 0.47, CH2Cl2). IR (CH2Cl2): 2928w, 2864w, 1605w, 1493w, 1453m, 1419w, 1366w, 1093s, 1027w.
1H-NMR (300 MHz, CDCl3): 7.61 ± 7.14 (m, 17 arom. H); 6.98 ± 6.89 (m, 2 arom. H); 5.63 (s, PhCH); 5.27
(d, J ˆ 11.2, PhCH); 4.93 (d, J ˆ 12.4, PhCH); 4.85 (d, J ˆ 12.4, PhCH); 4.64 (d, J ˆ 11.5, PhCH); 4.56 ± 4.54
(m, HCOB); 4.26 (t, J ˆ 9.6, HÀC(6)); 4.22 (dd, J ˆ 10.3, 5.0, HeqÀC(8)); 4.19 (d, J ˆ 2.5, HÀC(4)); 3.83 (t, J ˆ
10.3, HaxÀC(8)); 3.75 (dd, J ˆ 10.0, 2.5, HÀC(5)); 3.27 (td, J ˆ 9.6, 4.6, HÀC(7)); 2.53 (td, J ꢀ 13, 5, HÀC(1));
2.40 (td, J ꢀ 13, 5, H'ÀC(1)); 2.01 ± 1.26 (m, 15 H). 11B-NMR (160 MHz, CDCl3): 53.9 (br. s). 13C-NMR
(125 MHz, CDCl3): 140.66, 139.17, 138.75, 137.96, 131.40 (5s); 129.41 ± 126.06 (several d); 101.26 (d, PhCH);
79.75, 79.54, 78.22 (3d, C(4), C(5), C(6)); 75.62 (t, PhCH2); 74.67 (d, HCOB); 72.32 (t, PhCH2); 71.13 (d, C(7));
69.17 (t, C(8)); 34.13 (t, C(2)); 32.73, 29.79, 29.71, 27.30, 26.21, 22.80 (6t); 22.64 (small br. d, HCB); 21.22 (t);
‡
‡
signal for C(3) missing. FAB-MS (3-NOBA): 707 (31, M ), 599 (100). HR-FAB-MS: 707.3302 ([M ‡ H] ; calc.
707.3311).
Data of 19: Rf(hexane/AcOEt/CH2Cl2 4 :1:1) 0.62. tR(hexane/AcOEt 12 :1, 9 ml/min) 12 min. [a]2D5 ˆ À18.4
(c ˆ 0.37, CH2Cl2). IR (CH2Cl2): 2929w, 1605w, 1492m, 1453m, 1367w, 1094s, 1028w, 1015w. 1H-NMR (300 MHz,
CDCl3): 7.60 ± 7.51 (m, 2 arom. H); 7.40 ± 7.21 (m, 15 arom. H); 7.10 ± 7.05 (m, 2 arom. H); 5.70 (s, PhCH); 5.30
(d, J ˆ 10.6, PhCH); 4.91 (d, J ˆ 12.4, PhCH); 4.71 (d, J ˆ 12.4, PhCH); 4.64 ± 4.62 (m, HCOB); 4.57 (d, J ˆ 10.9,
PhCH); 4.36 (t, J ˆ 9.3, HÀC(6)); 4.28 (dd, J ˆ 10.3, 4.6, irrad. at 3.94 ! d, J ꢀ 5, HeqÀC(8)); 4.02 (dd, J ˆ 9.6,
2.5, HÀC(5)); 3.97 (d, J ˆ 2.7, HÀC(4)); 3.94 (t, J ˆ 10.3, HaÀC(8)); 3.65 (td, J ˆ 9.6, 4.7, irrad. at 3.94 ! t, J ꢀ 6,
HÀC(7)); 2.59 (br. td, J ꢀ 13, 5, irrad. at 2.05 ! m, irrad. at 3.65 ! NOE of 1%, HÀC(1)); 2.41 (br. td, J ꢀ 13, 5,
irrad. at 2.05 ! m, H'ÀC(1)); 2.05 (br. td, J ꢀ 13, 5, irrad. at 2.50 ! change, irrad. at 4.02 ! NOE of 2%, irrad. at
3.65 ! NOE of 2%, HÀC(2)); 2.17 ± 1.26 (m, 14 H). 11B-NMR (160 MHz, CDCl3): 53.2 (br. s). 13C-NMR
(125 MHz, CDCl3): 140.73, 139.20, 138.82, 137.88, 131.64 (5s); 129.54 ± 126.00 (several d); 101.26 (d, PhCH);
81.07, 80.51, 78.36 (3d, C(4), C(5), C(6)); 74.40 (d, CHOB); 74.30, 73.35 (2t, 2 PhCH2); 69.68 (t, C(8)); 65.55
(d, C(7)); 32.92 (t); 32.11 (t, C(2)); 30.60, 30.52, 25.91, 25.27, 23.10, 21.60 (6t); 20.91 (small d, BCH); signal for
‡
C(3) missing. FAB-MS (3-NOBA): 707 (100, M ), 663 (37), 461 (14), 355 (26). HR-FAB-MS: 707.3302 ([M ‡
‡
H] ; calc. 707.3311).
10-(8,9-Di-O-benzyl-10,12-O-benzylidene-1,2,3,4,5,6-hexadeoxy-a-d-manno-dodec-7-ulo-7,11-pyranosyl)-
9-oxa-10-borabicyclo[3.3.2]decane (20) and 10-(8,9-Di-O-benzyl-10,12-O-benzylidene-1,2,3,4,5,6-hexadeoxy-b-
d-manno-dodec-7-ulo-7,11-pyranosyl)-9-oxa-10-borabicyclo[3.3.2]decane (21). The soln. of the thermolysis of
the diazirine 15 (24 mg, 0.05 mmol) in the presence of 6 (50 mg, 0.22 mmol) in THF (1.5 ml) was evaporated at

1556
Helvetica Chimica Acta ± Vol. 83 (2000)
208. FC (hexane/AcOEt/CH2Cl2 25 :1:1) gave 20/21 30 :70 (10 mg, 31%) as a colourless oil. Anal. samples of 21
and 20 were obtained by prep. HPLC (hexane/AcOEt 15 :1, 9 ml/min).
Data of 21: Rf(hexane/AcOEt/CH2Cl2 5 :1:1) 0.54. tR(hexane/AcOEt 15 :1, 9 ml/min) 9 min. 1H-NMR
(300 MHz, CDCl3): 7.55 ± 7.51 (m, 2 arom. H); 7.40 ± 7.20 (m, 13 arom. H); 5.68 (s, PhCH); 5.9 (d, J ˆ 10.9,
PhCH); 4.93 (d, J ˆ 12.4, PhCH); 4.75 (d, J ˆ 12.1, PhCH); 4.6 ± 4.55 (m, BCH); 4.55 (d, J ˆ 10.9, PhCH); 4.32
(t, J ˆ 9.6, HÀC(10)); 4.24 (dd, J ˆ 10.3, 4.7, HeqÀC(12)); 4.05 (dd, J ˆ 9.9, 2.8, HÀC(9)); 3.96 (d, J ˆ 2.8,
HÀC(8)); 3.90 (t, J ˆ 10.3, HaxÀC(12)); 3.58 (td, J ˆ 9.6, 4.7, HÀC(11)); 1.91 ± 1.12 (m, 23 H); 0.88 (t, J ˆ 6.2,
‡
Me). FAB-MS (3-NOBA): 653 (3, [M ‡ H] ), 301 (14).
1
Data of 20: Rf(hexane/AcOEt/CH2Cl2 5 :1:1) 0.51. tR(hexane/AcOEt 15 :1, 9 ml/min) 11.8 min. H-NMR
(300 MHz, CDCl3): 7.52 ± 7.26 (m, 15 arom. H); 5.60 (s, PhCH); 5.19 (d, J ˆ 11.2, PhCH); 4.89 (d, J ˆ 12.6,
PhCH); 4.83 (d, J ˆ 12.4, PhCH); 4.63 (d, J ˆ 11.2, PhCH); 4.53 ± 4.48 (m, BCH); 4.23 (t, J ˆ 9.6, HÀC(10));
4.17 (dd, J ꢀ 10, 6, HeqÀC(12)); 4.13 (d, J ˆ 2.5, HÀC(8)); 3.81 (t, J ˆ 10.3, HaxÀC(12)); 3.75 (dd, J ˆ 9.9, 2.5,
HÀC(9)); 3.20 (td, J ˆ 9.9, 5.0, HÀC(11)); 1.90 ± 1.10 (m, 23 H); 0.85 (t, J ˆ 6.5, Me). FAB-MS (3-NOBA): 653
‡
(7, [M ‡ H] ), 545 (14), 455 (12).
4,5,6,8-Tetra-O-benzyl-1-C-(4-chlorophenyl)-1,2-dideoxy-a-d-gluco-oct-3-ulo-3,7-pyranose (24). A soln. of
9/8 25 :30 (16 mg, 0.02 mmol) in THF (1 ml) was treated with 3m aq. NaOH (0.6 ml) and 30% H2O2 (0.6 ml),
stirred at 258 for 24 h (TLC showed complete disappearance of 9 after 10 h and complete disappearance of 8
after 24 h). The mixture was diluted with CH2Cl2, washed with sat. aq. NaHCO3 soln., dried (MgSO4), and
evaporated. FC (hexane/AcOEt/CH2Cl2 10 :1:1) yielded 24 (13 mg, 100%) as a colourless oil. Rf(hexane/
AcOEt/CH2Cl2 4 :1:1) 0.17. [a]2D5 ˆ ‡12.0 (c ˆ 0.44, CH2Cl2). IR (CH2Cl2): 3566w, 3032m, 2926m, 2867m,
1
1605w, 1492m, 1453m, 1361m, 1091s, 1065s. H-NMR (300 MHz, CDCl3): 7.38 ± 7.20 (m, 2 arom. H); 7.05 ± 7.02
(m, 2 arom. H); 4.94 (d, J ˆ 11.2, 2 PhCH); 4.86 (d, J ˆ 10.9, PhCH); 4.84 (d, J ˆ 10.9, PhCH); 4.76 (d, J ꢀ 10,
PhCH); 4.64 (d, J ꢀ 10, PhCH); 4.63 (d, J ꢀ 12, PhCH); 4.55 (d, J ˆ 12.4, PhCH); 4.03 ± 3.97 (d, HÀC(7)); 4.00
(t, J ˆ 9.0, irrad. at 3.44 ! d, J ꢀ 9, HÀC(5)); 3.79 (dd, J ˆ 10.9, 3.7, HÀC(8)); 3.73 ± 3.66 (d, HÀC(6),
H'ÀC(8)); 3.44 (d, J ˆ 9.3, HÀC(4)); 2.75 ± 2.59 (m, 2 HÀC(1)); 2.64 (s, OH); 2.01 ± 1.85 (m, 2 HÀC(2)).
13C-NMR (75 MHz, CDCl3): 140.73, 138.81, 138.64, 138.52, 138.00, 131.75 (6s); 130.01 ± 127.83 (several d); 98.14
(s, C(3)); 84.03 (d, C(5)); 82.07 (d, C(4)); 78.50 (d, C(6)); 75.76, 75.63, 75.05, 73.50 (4t, 4 PhCH2); 71.83
‡
(d, C(7)); 68.90 (t, C(8)); 40.21 (t, C(2)); 28.12 (t, C(1)). FAB-MS (3-NOBA): 701 (27, [M ‡ Na] ), 553 (95),
253 (61), 181 (100). Anal. calc. for C42H43ClO6 (679.27): C 74.27, H 6.38; found: C 74.44, H6.32.
10-(1-C-Cyclopentyl-a-d-glucopyranosyl)-9-oxa-10-borabicyclo[3.3.2]decane (25). A suspension of 10%
Pd on activated charcoal (10 mg) in AcOEt/MeOH (1:1, 1 ml) was hydrogenated for 10 min. at 1 bar, added to
12 (10 mg, 0.141 mmol) and hydrogenated for 14 h at 5 bar. The suspension was filtered through Celite and
evaporated. FC (CH2Cl2/MeOH 93 :7) yielded 25 (4 mg, 80%) as a colourless oil. Rf(CH2Cl2/MeOH 10 :1) 0.37.
1H-NMR (300 MHz, CD3OD): 4.76 ± 4.75 (m, HCOB); 3.80 (dd, J ˆ 11.5, 2.2, HÀC(6)); 3.57 (dd, J ˆ 11.5, 5.9,
irrad. at 3.80 ! t, J ꢀ 5, H'ÀC(6)); 3.40 (dd, J ˆ 10.0, 8.7, irrad. at 3.11 ! dd, J ꢀ 10, 3, HÀC(3)); 3.37 ± 3.25
(m, 2 H); 3.11 (dd, J ˆ 10.0, 8.7, HÀC(4)); 2.30 ± 2.24 (m, 1 H); 2.27 ± 1.41 (m, 21 H). 11B-NMR (160 MHz,
CD3OD): 55.6 (br. s). 13C-NMR (75 MHz, CD3OD): 79.50, 79.29, 78.63, 76.83 (4d); 73.19 (d, CHOB); 64.33
(t, C(6)); 45.35 (d, C(1')); 32.33, 32.26, 28.07, 27.88, 27.73, 27.60, 26.96, 26.08 (8t); 24.3 (small br. d, HCB); 23.49,
‡
23.10 (2t). ESI-MS: 367 (100, [M À H]À), 391 (100, [M ‡ Na] ). Anal. calc. for C19H33BO6 (368.28): C 61.97,
H9.03; found: C 61.79, H 9.00.
(1R)-1,5-Anhydro-1-C-cyclopentyl-1,2-dideoxy-d-arabino-hexitol (26).
A suspension of 10% Pd on
activated charcoal (10 mg) in AcOEt/MeOH (1:1, 1 ml) was hydrogenated at 5 bar for 30 min, added to 13
(10 mg, 0.141 mmol), hydrogenated at 5 bar for 14 h, and filtered through Celite. Evaporation and FC (CH2Cl2/
MeOH 9 :1) yielded 26 (2 mg, 60%) as a white solid. Rf(CH2Cl2/MeOH 10 :1) 0.27. 1H-NMR (300 MHz,
CD3OD): 3.82 (dd, J ˆ 11.8, 2.2, irrad. at 3.19 ! d, J ꢀ 11, HÀC(6)); 3.64 (dd, J ˆ 11.8, 5.3, irrad. at. 3.19 !
d, J ꢀ 11, H'ÀC(6)); 3.51 (ddd, J ˆ 11.2, 8.4, 5.0, irrad. at 3.19 ! dd, J ꢀ 11, 6, irrad. at. 1.98 ! dd, J ꢀ 10, 8, irrad.
at 1.3 ! m, HÀC(3)); 3.21 ± 3.12 (m, irrad. at 3.51, 1.98, or 1.3 ! change, HÀC(1), HÀC(4), HÀC(5)); 1.98
(ddd, 12.8, 5.3, 1.9, irrad. at 3.51 ! dd, J ꢀ 13, 2, HeqÀC(2)); 1.94 ± 1.39 (m, 8 H); 1.34 ± 1.22 (m, 1 H); 1.28
(dt, J ˆ 12.8, 11.5, irrad. at 3.51, 3.19, or 1.98 ! t, J ꢀ 12, HaxÀC(2)). 13C-NMR (75 MHz, CD3OD): 81.69, 81.08
(2d, C(1), C(5)); 74.27, 73.81 (2d, C(3), C(4)); 63.43 (t, C(6)); 46.20 (d, C(1')); 39.52 (t, C(2)); 30.33, 29.79,
‡
‡
26.64, 26.47 (4t). ESI-MS (NH4OHc): 275 (100, [M ‡ OAc]À), 239 (95, [M ‡ Na] ), 234 (56, [M ‡ NH4] ).
4,5,6,8-Tetra-O-benzyl-1,2-dideoxy-a-d-gluco-oct-3-ulo-3,7-pyranose (29) and 3,7-Anhydro-5,6,8-tri-O-ben-
zyl-1,2,4-trideoxy-d-arabino-oct-3-enitol (30). The soln. of the thermolysis of the diazirine 1 (112 mg, 0.2 mmol)
in the presence of 1m BEt3 (in hexane, 300 ml, 0.3mmol) in degassed THF (3 ml) at 308 was cooled to 08, treated
with 3m aq. NaOH (0.7 ml) and 30% H2O2 (0.7 ml), and stirred at 258 for 12 h. The suspension was diluted with

Helvetica Chimica Acta ± Vol. 83 (2000)
1557
CH2Cl2, washed with sat. aq. NaHCO3 soln. and H2O, dried (MgSO4), and evaporated. FC (hexane/AcOEt/
CH2Cl2 8 :1:1) gave 30 (12 mg, 13%) and 29 (40 mg, 55%) as colourless oils.
Data of 30: Rf(hexane/AcOEt/CH2Cl2 4 :1:1) 0.57. [a]2D5 ˆ ‡1.3 (c ˆ 1.30, CHCl3). IR (CHCl3): 3090w,
3065w, 3000w, 2920w, 2870m, 1675m, 1495w, 1455m, 1365w, 1170w, 1090s, 1025m. 1H-NMR (400 MHz, CDCl3):
7.36 ± 7.27 (m, 15 arom. H); 4.82 (d, J ˆ 11.4, PhCH); 4.67 (br. d, J ꢀ 4, HÀC(4)); 4.66 (d, J ˆ 11.3, PhCH); 4.63
(d, J ˆ 11.7, PhCH); 4.61 (d, J ˆ 12.1, PhCH); 4.57 (d, J ˆ 12.1, PhCH); 4.55 (d, J ˆ 11.7, PhCH); 4.19 ± 4.17
(m, HÀC(5)); 4.10 (ddd, J ˆ 8.0, 5.0, 3.0, HÀC(7)); 3.84 (dd, J ˆ 8.1, 5.6, HÀC(6)); 3.82 (dd, J ˆ 10.8, 5.0,
HÀC(8)); 3.78 (dd, J ˆ 10.8, 3.0, H'ÀC(8)); 2.14 ± 2.09 (m, 2 HÀC(2)); 1.07 (t, J ˆ 7.5, Me). 13C-NMR (50 MHz,
CDCl3): 157.68 (s, C(3)); 138.57, 138.31, 138.28 (3s); 128.33 ± 127.50 (several d); 93.76 (d, C(4)); 76.71 (d); 76.04
(d); 74.34 (d); 73.39, 73.29, 70.25 (3t, 3 PhCH2); 68.91 (t, C(8)); 26.56 (t, C(2)); 11.20 (q, C(1)). CI-MS: 445 (1.4,
‡
M ), 337 (100), 253 (12), 91 (28). Anal. calc. for C29H32O4 (444.67): C 78.35, H 7.26; found: C 78.26, H 7.13.
Data of 29: Rf(hexane/AcOEt/CH2Cl2 4 :1:1) 0.25. [a]2D5 ˆ ‡29.0 (c ˆ 1.32, CHCl3). IR (CHCl3): 3585w,
3090w, 3065w, 3000m, 2980m, 2870m, 1600w, 1495w, 1453m, 1360m, 1290w, 1085s, 1025m. 1H-NMR (400 MHz,
CDCl3): 7.39 ± 7.23 (m, 20 arom. H); 4.95 (d, J ˆ 11.1, PhCH); 4.94 (d, J ˆ 11.0, PhCH); 4.89 (d, J ˆ 11.0, PhCH);
4.86 (d, J ˆ 10.9, PhCH); 4.71 (d, J ˆ 11.1, PhCH); 4.65 (d, J ˆ 12.3, PhCH); 4.64 (d, J ˆ 10.9, PhCH); 4.57
(d, J ˆ 12.3, PhCH); 4.04 (t, J ˆ 9.2, HÀC(5)); 4.02 (ddd, J ˆ 10.0, 3.9, 1.9, HÀC(7)); 3.80 (dd, J ˆ 11.0, 3.9,
HÀC(8)); 3.71 ± 3.67 (m, HÀC(6), H'ÀC(8)); 3.47 (d, J ˆ 9.4, HÀC(4)); 2.61 (s, OH); 1.78 ± 1.72
(m, 2 HÀC(2)); 0.93 (t, J ˆ 7.4, Me). 13C-NMR (50 MHz, CDCl3): 138.59, 138.36, 138.24, 137.89 (4s); 128.36 ±
127.36 (several d); 98.36 (s, C(3)); 83.77 (d, C(5)); 81.11 (d, C(4)); 78.46 (d, C(6)); 75.45, 75.27, 74.75 (3t,
3 PhCH2); 74.49 (d, C(7)); 73.21 (t, PhCH2); 68.78 (t, C(8)); 31.33 (t, C(2)); 6.86 (q, C(1)). CI-MS: 551 (12,
‡
[M À OH] ), 443 (100). Anal. calc. for C36H40O6 (568.71): C 76.03, H 7.09; found: C 75.88, H 7.05.
31,7-Anhydro-4,5,6,8-tetra-O-benzyl-3-C-ethyl-3-C-(ethylhydroxyboryl)-1,2,3-trideoxy-d-gluco-octitol (41).
The soln. of the thermolysis of the diazirine 1 (25 mg, 0.045 mmol) in the presence of 1m BEt3 (in THF, 61 ml,
0.061 mmol) in degassed THF (2 ml) was cooled to 08, treated with CF3COOH (18 ml, 0.24 mmol), and stirred
for 12 h at 258. The soln. was diluted with AcOEt, washed with sat. aq. NaHCO3 soln. and brine, dried (MgSO4),
and evaporated at 258. FC (hexane/AcOEt/CH2Cl2 8 :1:1) yielded 41 (13 mg, 46%) as a colourless oil.
Rf(hexane/AcOEt/CH2Cl2 4 :1:1) 0.53. IR (CH2Cl2): 3031m, 2962m, 1496w, 1454w, 1095s, 1013s. 1H-NMR
(300 MHz, CDCl3): 7.39 ± 7.20 (m, 20 arom. H); 4.77 (ddd, J ˆ 9.6, 3.7, 2.2, HÀC(7)); 4.74 (d, J ˆ 12.1, PhCH);
4.65 (d, J ˆ 12.1, PhCH); 4.59 (s, PhCH2); 4.58 (d, J ꢀ 12, PhCH); 4.55 (d, J ꢀ 12, PhCH); 4.47 (d, J ˆ 11.8,
PhCH); 4.34 (d, J ˆ 11.5, PhCH); 3.94 (t, J ˆ 4.3, HÀC(5)); 3.88 (dd, J ˆ 10.9, 4.0, irrad. at 4.77 ! d, J ꢀ 11,
HÀC(8)); 3.81 (dd, J ˆ 11.0, 2.1, irrad. at 4.77 ! d, J ꢀ 11, H'ÀC(8)); 3.79 (dd, J ˆ 9.4, 4.1, irrad. at 4.77 ! d, J ꢀ
4, HÀC(6)); 3.60 (d, J ˆ 4.9, HÀC(4)); 1.72 (dq, J ˆ 14.3, 7.2, MeCH2); 1.59 ± 1.51 (m, 1 H); 1.41 (dq, J ˆ 14.6,
7.8, MeCH2); 0.92 ± 0.74 (m, 11 H). 11B-NMR (160 MHz, CDCl3): 53.16 (br. s). 13C-NMR (75 MHz, CDCl3):
139.39, 139.23, 138.73, 138.34 (4s); 128.57 ± 127.45 (several d); 81.55 (d); 81.27 (d); 78.47 (d); 74.46 (d); 73.86,
73.81, 72.70, 72.57 (4t, 4 PhCH2); 71.66 (t, C(8)); 26.43, 21.79 (2t, 2 MeCH2); 9.96, 8.42, 8.16 (3q, 3 Me); signals
for C(3) and BÀCH2Me missing.
4,5,6,8-Tetra-O-benzyl-1,2-dideoxy-3-C-ethyl-d-gluco-octitol (42). A soln. of 41 (10 mg, 0.106 mmol) in
CDCl3 (0.7 ml) was diluted with THF (2 ml), cooled to 08, treated with 3m aq. NaOH (0.7 ml) and 30% H2O2
(0.7 ml), and stirred for 3 h at 258. The suspension was diluted with CH2Cl2, washed with sat. aq. NaHCO3 soln.
and H2O, dried (MgSO4), and evaporated. FC (hexane/AcOEt/CH2Cl2 8 :1:1) gave 42 (7 mg, 73%) as a
colourless oil. Rf(hexane/AcOEt/CH2Cl2 4 :1:1) 0.17. [a]2D5 ˆ À8.2 (c ˆ 0.32, CH2Cl2). IR (CH2Cl2): 3599m,
3478m, 3032m, 2966m, 1605m, 1496m, 1454m, 1093s, 1069s. 1H-NMR (300 MHz, CDCl3): 7.37 ± 7.26
(m, 20 arom. H); 4.94 (d, J ˆ 11.2, PhCH); 4.75 (d, J ˆ 10.9, PhCH); 4.69 (d, J ˆ 11.5, PhCH); 4.56 ± 4.47
(m, 5 PhCH); 4.17 (br. t, J ꢀ 6, 1 H); 4.13 (dd, J ˆ 6.2, 3.1, 1 H); 3.66 ± 356 (m, 4 H); 3.17 (br. d, J ꢀ 6,
exchangeable with D2O, HOÀC(7)); 2.33 (s, exchangeable with D2O, HOÀC(3)); 1.71 ± 1.24 (m, 4 H); 0.77
(t, J ˆ 7.5, Me); 0.73 (t, J ˆ 7.5, Me). 13C-NMR (100 MHz, CDCl3): 138.92, 137.96, 137.90, 137.67 (4s); 128.69 ±
127.34 (several d); 79.99 (d); 78.50 (d); 77.55 (d); 76.70 (s, C(3)); 74.54, 74.40, 73.48, 73.04 (4t, 4 PhCH2); 71.49
‡
(t, C(8)); 70.45 (d, C(7)); 29.68, 27.61 (2t, 2 MeCH2); 7.98, 7.30 (2q, 2 Me). DCI-MS (NH4): 599 (<1, [M ‡ H] ),
‡
‡
581 (<1, [M À OH] ), 491 (<1, [M À OBn] ), 337 (19), 253 (75), 91 (100). Anal. calc. for C38H46O6 (598.78):
C 76.22, H 7.74; found: C 76.05, H 7.74.
5,6,8-Tri-O-benzyl-1,2,3,4-tetradeoxy-3-C-ethyl-d-arabino-oct-3-enitol (43).
A
soln. of 41 (9 mg,
0.014 mmol) in degassed CDCl3 (0.7 ml) was kept at 258 for 80 h and evaporated. FC (hexane/AcOEt/CH2Cl2
8 :1:1) gave 43 (6 mg, 88%). Rf(hexane/AcOEt/CH2Cl2 4 :1.1) 0.34. [a]2D5 ˆ À20.0 (c ˆ 0.18, CH2Cl2). IR
(CH2Cl2): 3587w, 3032w, 2966m, 2874m, 1662w, 1605w, 1496w, 1454m, 1086s. 1H-NMR (300 MHz, CDCl3): 7.33 ±
7.18 (m, 15 arom. H); 5.31 (br. d, J ꢀ 9, CˆCH); 4.65 (d, J ˆ 11.5, PhCH); 4.59 (d, J ˆ 12.1, PhCH); 4.56 (d, J ˆ
11.5, PhCH); 4.49 (s, PhCH2); 4.41 (dd, J ˆ 9.3, 3.8, irrad. at 5.31 ! d, J ꢀ 4, HÀC(5)); 4.31 (d, J ˆ 12.1, PhCH);

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Helvetica Chimica Acta ± Vol. 83 (2000)
4.06 ± 4.00 (m, addn. of D2O ! change, HÀC(7)); 3.55 ± 3.59 (m, 3 H); 2.93 (d, J ˆ 5.3, exchangeable with D2O,
OH); 2.08 (qd, J ˆ 7.5, 1.2, irrad. at 5.31 ! q, J ꢀ 7, MeCH2); 1.99 (m, MeCH2); 1.01 (t, J ˆ 7.5, Me); 0.91 (t, J ˆ
7.5, Me). 13C-NMR (100 MHz, CDCl3): 148.66 (s, C(3)); 138.35, 138.27, 138.09 (3s); 128.35 ± 127.58 (several d);
120.14 (d, C(4)); 81.34 (d, C(6)); 74.74 (d, C(5)); 74.18, 73.24, 71.25 (3t, 3 PhCH2); 70.61 (d); 69.85 (t, C(8));
‡
28.87, 23.69 (2t, 2 MeCH2); 13.13, 12.67 (2q, 2 Me). DCI-MS (NH4): 492 (<1, [M ‡ NH4] ), 475 (<1, [M ‡
‡
‡
H] ), 259 (11), 203 (70, [M À CHOBnÀCHOHÀCH2OBn] ), 91 (100). Anal. calc. for C31H38O4 (474.64):
C 78.45, H 8.07, O 13.48; found: C 78.62, H 7.99.
4,5-Di-O-benzyl-6,8-O-benzylidene-1,2-dideoxy-a-d-gluco-oct-3-ulo-3,7-pyranose (38). A soln. of 1m BEt3
(in THF, 0.1 ml, 0.1 mmol) in dry THF (1.5 ml) was treated with a soln. of 14 (30 mg, 0.065 mmol) in dry CH2Cl2
(1.9 ml) and stirred at 308 for 6 h (complete consumption of 14). The soln. was cooled to 08, treated with 3m aq.
NaOH (0.3 ml) and 30% H2O2 (0.3 ml), stirred at 258 for 12 h, diluted with CH2Cl2, washed with aq. sat
NaHCO3 soln. and brine, dried (MgSO4), and evaporated. FC (hexane/AcOEt/CH2Cl2 8 :1:1) gave 38 (19 mg,
60%) as a colourless oil. Rf(hexane/AcOEt/CH2Cl2 4 :1:1) 0.27. [a]2D5 ˆ À3.1 (c ˆ 0.35, CH2Cl2). IR (CH2Cl2):
3596w, 2927m, 2856m, 1605m, 1497w, 1454m, 1373m, 1094s. 1H-NMR (300 MHz, CDCl3): 7.52 ± 7.22
(m, 15 arom. H); 5.58 (s, PhCH); 5.00 (d, J ˆ 11.2, PhCH); 4.98 (d, J ˆ 10.9, PhCH); 4.78 (d, J ˆ 11.2, PhCH);
4.70 (d, J ˆ 10.9, PhCH); 4.31 (dd, J ˆ 10.3, 5.0, HeqÀC(8)); 4.07 (t, J ˆ 9.3, irrad. at 3.48 ! dd, J ꢀ 10, 2,
HÀC(5)); 4.04 (td, J ˆ 10.3, 5.0, irrad. at 4.31 ! t, J ꢀ 10, HÀC(7)); 3.71 (t, J ˆ 10.3, irrad. at 4.31 ! d, J ꢀ 10,
HaxÀC(8)); 3.64 (t, J ˆ 9.7, HÀC(6)); 3.48 (d, J ˆ 8.7, HÀC(4)); 2.79 (s, OH); 1.77 ± 1.67 (m, 2 HÀC(2)); 0.86
(t, J ˆ 7.2, Me). 13C-NMR (75 MHz, CDCl3): 138.81, 138.06, 137.80 (3s); 129.15 ± 126.28 (several d); 101.39
(d, PhCH); 99.56 (s, C(3)); 82.68 (d, C(6)); 80.76, 80.66 (2d, C(4), C(5)); 75.84, 75.36 (2t, 2 PhCH2); 69.35
(t, C(8)); 63.18 (d, C(7)); 31.73 (t, C(2)); 6.83 (q, C(1)). Anal. calc. for C29H32O6 (476.57): C 73.09, H 6.77;
found: C 73.28, H 6.87.
(E,E)-2,3-Di-O-benzyl-4,6-O-benzylidene-d-glucono-1,5-lactone Azine (37).
A soln. of 14 (38 mg,
0.083 mmol) in CH2Cl2 (0.45 ml) was diluted with MeCN (2 ml, dried over molecular sieves), stirred at 258
for 20 h, and evaporated at 208. FC (hexane/AcOEt/CH2Cl2 8 :1:1) gave 37 (15 mg, ca. 35%), together with
traces of other products. Crystallisation (AcOEt/hexane) gave an anal. sample of 37. Rf(hexane/AcOEt/CH2Cl2
4 :1:1) 0.63. IR (CH2Cl2) 3040m, 2986s, 1636m, 1496w, 1453w, 1441s, 1087s, 1028m, 1009m, 885s. 1H-NMR
(300 MHz, C6D6): 7.59 ± 7.05 (m, 15 arom. H); 6.03 (br. s, HÀC(2)); 5.16 (s, PhCH); 4.76 ± 4.67 (m, HÀC(5));
4.74 (d, J ˆ 11.2, PhCH); 4.69 (d, J ˆ 11.5, PhCH); 4.52 (d, J ˆ 12.4, PhCH); 4.43 (d, J ˆ 12.4, PhCH); 4.24
(dd, J ˆ 10.3, 5.3, irrad. at 3.46 ! d, J ꢀ 5, HeqÀC(6)); 4.23 (d, J ˆ 6.8, irrad. at 3.79 ! s, HÀC(3)); 3.79 (dd, J ˆ
10.3, 6.8, irrad. at 4.23 ! d, J ꢀ 10, HÀC(4)); 3.46 (t, J ˆ 10.3, irrad. at 4.23 ! d, J ꢀ 10, HaxÀC(6)). 13C-NMR
(75 MHz, C6D6): 164.56 (s, C(1)); 138.17, 137.99, 137.91 (3s); 129.12 ± 126.62 (several d); 101.64 (d, PhCH); 81.47,
80.63 (2d, C(3), C(4)); 72.02, 71.62 (2t, 2 PhCH2); 70.95 (d, C(2)); 68.99 (t, C(6)); 65.55 (d, C(5)). MALDI-MS:
‡
‡
889 (60, [M ‡ H] ), 888 (100, M ).
4,5-Di-O-benzyl-6,8-O-benzylidene-1,2-dideoxy-a-d-manno-oct-3-ulo-3,7-pyranose (39) and 3,7-Anhydro-
5-O-benzyl-6,8-O-benzylidene-1,2,4-trideoxy-d-arabino-oct-3-enitol (40). The soln. of the thermolysis of the
diazirine 15 (20 mg, 0.043 mmol) in the presence of 1m BEt3 (in THF, 92 ml, 0.092 mmol) in degassed THF (1 ml)
was cooled to 08, treated with 3m aq. NaOH (0.5 ml) and 30% H2O2 (0.5 ml), and stirred at 258 for 12 h. The
mixture was diluted with CH2Cl2, washed with sat. aq. NaHCO3 soln. and H2O, dried (MgSO4), and evaporated.
FC (hexane/AcOEt/CH2Cl2 8 :1 :1) gave an apolar mixture of 39 (9 mg, 43%) and 38 (2 mg, 9%) as colourless
oils. HPLC (hexane/AcOEt 8 :1; 9 ml/min) of the apolar mixture yielded a 1:1 mixture of the glucal 40 (<1 mg,
<5%) and another product.
Data of 39: Rf(hexane/AcOEt/CH2Cl2 4 :1:1) 0.23. 1H-NMR (300 MHz, CDCl3): 7.54 ± 7.26 (m, 15
arom. H); 5.63 (s, PhCH); 5.09 (d, J ˆ 11.2, PhCH); 4.95 (d, J ˆ 12.4, PhCH); 4.76 (d, J ˆ 12.2, PhCH); 4.67
(d, J ˆ 11.5, PhCH); 4.29 ± 4.19 (m, HÀC(5), HÀC(6), HeqÀC(8)); 4.00 (td, J ˆ 11.3, 4.7, HÀC(7)); 3.84 (t, J ˆ
10, HaxÀC(8)); 3.83 (d, J ˆ 2.5, HÀC(4)); 2.19 (s, exchangeable with CD3OD, OH); 1.81 (dq, J ˆ 14.3, 7.5, 1 H,
MeCH2); 1.70 (dq, J ˆ 14.6, 7.3, 1 H, MeCH2); 0.85 (t, J ˆ 7.7, Me ) . 13C-NMR (75 MHz, CDCl3): 138.90, 138.37,
137.77 (3s); 128.81 ± 126.10 (several d); 101.46 (d, PhCH); 100.75 (s, C(3)); 79.57, 77.94, 77.84 (3d, C(4), C(5),
C(6)); 75.25, 73.42 (2t, 2 PhCH2); 69.11 (t, C(8)); 64.88 (d, C(7)); 30.45 (t, C(2)); 6.67 (q, C(1)).
Data of 40: Rf(hexane/AcOEt/CH2Cl2 8 :1:1) 0.50. tR(hexane/AcOEt 8 :1, 9 ml/min) 10.6 min. 1H-NMR
(300 MHz, CDCl3): 7.61 ± 7.02 (m, 15 arom. H); 5.59 (s, PhCH); 4.90 ± 4.62 (m, PhCH2, HaxÀC(8)); 4.57
(dq, J ꢀ 7, 1, H ÀC(4)); 4.41 (dd, J ˆ 10.3, 5.0, HeqÀC(8)); 4.16 (dd, J ˆ 9.9, 7.2, HÀC(5)); 3.99 (td, J ˆ 10.3, 5.0,
HÀC(7)); 3.85 (t, J ˆ 10.3, HÀC(6)); 2.23 ± 2.16 (m, MeCH2); 0.93 (t, J ˆ 7.5, MeCH2); further signals: 7.61 ±
7.02 (m, 15 arom. H); 5.58 (s, PhCH); 4.90 ± 4.62 (m, 3 H); 4.57 (d, J ˆ 7.1); 4.37 (dd, J ˆ 10.3, 5.0); 4.08 (dd, J ˆ
9.9, 7.2); 3.84 (t, J ˆ 10.3); 3.72 (td, J ˆ 10.3, 5.0).

Helvetica Chimica Acta ± Vol. 83 (2000)
1559
4,8-Anhydro-2-C-methyl-5,6,7,9-tetra-O-benzyl-1,2,3-trideoxy-d-glycero-d-gulo-nonitol (46) and 4,8-Anhy-
dro-2-C-methyl-1,2,3,5-tetradeoxy-6,7,9-tri-O-benzyl-d-arabino-non-4-enitol (48). The soln. of the thermolysis of
the diazirine 1 (35 mg, 0.064 mmol) in the presence of 1m Al(iBu)3 (in heptane, 84 ml, 0.084 mmol) in THF
(1.5 ml) was cooled to 08, treated with H2O (0.5 ml), and stirred for 12 h. The mixture was diluted wtih CH2Cl2,
washed with sat. aq. NH4Cl, NaHCO3, and H2O, dried (MgSO4), and evaporated. FC (hexane/AcOEt/CH2Cl2
18 :1:1) yielded 48 (8 mg, 26%) and 46 (8 mg, 21%) as colourless oils.
Data of 46: Rf(hexane/AcOEt/CH2Cl2 4 :1:1) 0.62. IR (CH2Cl2): 3032w, 2956m, 2869m, 1496m, 1453m,
1364m, 1208m, 1083s, 1027m. 1H-NMR (300 MHz, CDCl3): 7.36 ± 7.10 (m, 20 arom. H); 4.95 (d, J ˆ 10.9,
PhCH); 4.82 (d, J ˆ 10.9, PhCH); 4.80 (d, J ˆ 10.9, PhCH); 4.69 (d, J ˆ 11.8, PhCH); 4.64 (d, J ˆ 12.5, PhCH);
4.60 (d, J ˆ 11.8, PhCH); 4.47 (d, J ˆ 12.1, PhCH); 4.45 (d, J ˆ 10.6, PhCH); 4.13 (ddd, J ˆ 11.8, 5.3, 2.8, irrad. at
3.73 ! dd, J ꢀ 11, 3, irrad. at 1.74 ! d, J ꢀ 5, HÀC(4)); 3.80 (dd, J ˆ 9.3, 7.8, HÀC(6) or HÀC(7)); 3.73 (dd, J ˆ
9.3, 5.6, irrad. at 4.13 ! d, J ꢀ 9, HÀC(5)); 3.69 ± 3.55 (m, 4 H); 1.80 ± 1.68 (m, 2 HÀC(3)); 1.40 ± 1.32
(m, HÀC(2)); 0.95 ± 0.89 (m, 2 Me). 13C-NMR (75 MHz, CDCl3): 138.85, 138.37, 138.26, 138.09 (4s); 128.44 ±
127.76 (several d); 82.63 (d, C(6)); 80.38 (d, C(5)); 78.26 (d, C(7)); 75.55, 75.14, 73.53, 73.10 (4t, 4 PhCH2);
72.08, 71.03 (2d, C(4), C(8)); 68.99 (t, C(9)); 33.01 (t, C(3)); 24.00 (d, C(2)); 23.82, 21.36 (2q, 2 Me). FAB-MS
‡
(3-NOBA): 581 (9, [M ‡ H] ), 502 (17), 391 (36), 349 (100).
Data of 48: Rf(hexane/AcOEt/CH2Cl2 4 :1:1) 0.70. IR (CH2Cl2): 3032w, 2957m, 2869m, 1673m, 1496w,
1453m, 1367w, 1097s, 1027m. 1H-NMR (300 MHz, CDCl3): 7.34 ± 7.26 (m, 15 arom. H); 4.80 (d, J ˆ 11.5, PhCH);
4.67 (d, J ˆ 3.4, irrad. at 4.18 ! change, HÀC(5)); 4.65 (d, J ˆ 10.9, PhCH); 4.62 (d, J ˆ 11.5, PhCH); 4.60
(d, J ˆ 11.8, PhCH); 4.55 (d, J ˆ 12.1, PhCH); 4.53 (d, J ˆ 11.8, PhCH); 4.18 (dd, J ˆ 5.6, 3.2, HÀC(6)); 4.09
(ddd, J ˆ 7.8, 5.0, 2.8, HÀC(8)); 3.83 (dd, J ˆ 8.0, 5.6, irrad. at 4.18 or 4.09 ! m, HÀC(7)); 3.82 (dd, J ˆ 10.9, 5.0,
irrad. at 4.09 ! m, HÀC(9)); 3.75 (dd, J ˆ 10.6, 2.8, irrad. at 4.09 ! d, J ꢀ 10, H'ÀC(9)); 1.97 ± 1.87 (m, 3 H);
0.92 ± 0.89 (m, 6 H). 13C-NMR (75 MHz, CDCl3): 155.40 (s, C(4)); 138.63 (s, 1 arom. C); 138.37 (s, 2 arom. C);
128.37 ± 127.53 (several d); 96.02 (d, C(5)); 75.90, 74.27 (2d); 73.39, 73.25, 70.11 (3t, 3 PhCH2); 68.77 (t, C(9));
43.02 (t, C(3)); 26.01 (d, C(2)); 22.41, 22.38 (2q, 2 Me).
Reaction of 1 with AlMe3. A soln. of 2m AlMe3 in heptane (52 ml, 0.103 mmol) and 1 (47 mg, 0.086 mmol) in
THF (1.5 ml) was stirred for 4.5 h at 188, cooled to 08, and treated with H2O (0.5 ml) and CH2Cl2 (20 ml). The
org. layer was separated, washed with 2n NaOH soln. and H2O, dried (MgSO4), and evaporated. FC (hexane/
AcOEt/CH2Cl2 10 :1:1) gave 51 [43] (11 mg, 30%) and 49 [42] (14 mg, 30%).
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Received March 25, 2000