Preparation of (aminomethyl)stannanes by reduction of α-amidoorgano stannanes

Full text of DOI:10.1021/jo9609135

J . Org. Chem. 1996, 61, 7627-7630
7627
Sch em e 1
P r ep a r a tion of (Am in om eth yl)sta n n a n es by
Red u ction of r-Am id oor ga n o Sta n n a n es
Andrew F. Burchat, J . Michael Chong,* and
Nathan Nielsen
Guelph-Waterloo Centre for Graduate Work in Chemistry,
Department of Chemistry, University of Waterloo,
Waterloo, Ontario, Canada N2L 3G1
Ta ble 1. Rea ction of Am id e 4a u n d er Differ en t
Con d ition s
Received May 17, 1996
R-Aminoorgano stannanes are becoming increasing
popular as reagents in organic synthesis.1,2 They were
first described by Peterson who showed that [(dialkyl-
amino)methyl]stannanes such as 1 may be transformed
into organolithium reagents which in turn may used as
nucleophiles to prepare â-amino alcohols (eq 1).3 Sub-
sequently, other workers have provided additional ex-
amples of this approach to â-amino alcohols.4,5 R-Ami-
nomethyl stannanes have also served as intermediates
in syntheses of R-amino ketones,6 R-amino acids,7 and
cyclic amines.2,8
entry
reducing agent
conditions
ratio 5a :6a
1
2
3
4
5
6
7
8
9
LiAlH4
LiAlH4
LiAlH4
LiAlH4
Et2O, reflux, 10 min
Et2O, reflux, 10 min
Et2O, 0 °C, 15 min
Et2O, 0 °C, 45 min
THF, reflux, 3 h
Et2O, reflux, 1 h
toluene, rt, 3.5 h
Et2O, reflux, 1 h
THF, rt, 30 min
14:1b
9.4:1c
18:1b
1:1c
LiAlH4
1:3.4d
8.8:1b
6.6:1d
5.2:1d
>50:1b
LiAl(OEt)2H2
DIBAL-H
DIBAL-H
AlH3
Determined by 1H NMR analysis of crude reaction products.
a
Amide 4a was added to a solution of the reducing agent. c Solid
LiAlH4 was added to a solution of amide 4a in Et2O. A solution
of the reducing agent was added to a solution of amide 4a .
b
d
report that R-aminoorgano stannanes may be prepared
in excellent yields by reduction of R-amidoorgano stan-
nanes.
[(Dialkylamino)methyl]stannanes have been classically
prepared by the reaction of amines with halomethylor-
gano stannanes2 or by reaction of Bu3SnM (M ) Li, MgCl)
with R2NCH2SR′3 or R2NCH2OR′.4 The former method
has the disadvantage of low yields, particularly when the
amine is hindered,9 while the latter method employs
Galvinoxyl (in the preparation of Bu3SnMgCl) which can
give rise to products which are detrimental to transmeta-
lation of the organostannane.10 More recently, Quintard
has introduced a method to (aminoorgano)stannanes via
addition of Bu3SnMgCl to iminium salts,5 Pearson has
reported a route which involves displacement of sulfones
with Bu3SnLi,11 and both Katrizky12 and Pearson13 have
shown that benzotriazoles may be useful precursors to
aminostannanes. R-Amino stannanes may also be pre-
pared by reduction of R-stannyl imines but this route is
limited since these imines are prepared from acylstan-
nanes which are notoriously air-sensitive.14 We now
The reduction of amides with hydride reagents is a
proven route to amines.15 Since the alkylation of amide
anions is a much cleaner reaction than the alkylation of
amines, the short sequence shown in Scheme 1 was an
attractive route to R-amino stannanes. Many secondary
amides are commercially available or easily prepared
while iodide 3 may be obtained in 100 g batches using
the method of Seitz.16 The one missing link was the
reduction itself since it was not known how the reduction
of the amide would be affected by the presence of the
tributylstannyl group.17
Resu lts a n d Discu ssion
In our initital investigations, N-benzylbenzamide was
alkylated with iodide 3 to give the expected amide 4a in
good yield. This amide was then treated with hydride
reagents; results are summarized in Table 1. Reductions
employing LiAlH4 gave the desired amine 5a in moderate
to good yields, but a minor side product was also formed.
This material was identified as N-methyldibenzylamine
(6).18 The presence of this side product along with Bu3-
SnH in the crude reduction mixture suggested that attack
of a hydride reagent on the tributyltin group was
competing with reduction of the carbonyl group.19 Treat-
(1) For a review of earlier work, see: Pereyre, M.; Quintard, J .-P.;
Rahm, A. Tin in Organic Synthesis; Butterworths: London, 1987; pp
172-173.
(2) For a compilation of recent work, see reference 2 in: Coldham,
I.; Hufton, R. Tetrahedron Lett. 1995, 36, 2157-2160.
(3) (a) Peterson, D. J . J . Organomet. Chem. 1970, 21, P63-P64. (b)
Peterson, D. J . J . Am. Chem. Soc. 1971, 93, 4027-4031. (c) Peterson,
D. J .; Ward, J . F. J . Organomet. Chem. 1974, 66, 209-217.
(4) Quintard, J .-P.; Elissondo, B.; J ousseaume, B. Synthesis 1984,
495-498.
(5) Elissondo, B.; Verlhac, J .-P.; Quintard, J .-P.; Pereyre, M. J .
Organomet. Chem. 1988, 339, 267-275.
(6) Verlhac, J .-B.; Quintard, J .-P. Tetrahedron Lett. 1986, 27, 2361-
2364.
(15) (a) Larock, R. C. Comprehensive Organic Transformations;
VCH: New York, 1991; pp 432-433. (b) March, J . Advanced Organic
Synthesis, 4th ed.; Wiley: New York, 1992; pp 1212-1213.
(16) Seitz, D. E.; Carroll, J . J .; Cartaya, M. C. P.; Lee, S.-H.; Zapata,
A. Synth. Commun. 1983, 13, 129-134.
(17) BOC-protected aminostannanes have been reduced with
DIBAL-H to the corresponding N-methyl compounds: (a) Gawley, R.
E.; Zhang, Q. Tetrahedron 1994, 50, 6077-6088. (b) Gawley, R. E.;
Zhang, Q. J . Org. Chem. 1995, 60, 5763-5769.
(18) Gribble, G. W.; Nutaitis, C. F. Synthesis 1987, 709-711.
(19) Formation of Bu3SnH in reductions of R-epoxy stannanes has
previously been observed: Chong. J . M.; Mar, E. K. J . Org. Chem. 1992,
57, 46-49.
(7) Ekhato, I. V.; Huang, C. C. J . Labelled Compd. and Radiopharm.
1994, 34, 107-115.
(8) Coldham, I. J . Chem. Soc., Perkin Trans. 1 1993, 1275-1276.
(9) Abel, E. W.; Rowley, R. J . J . Organomet. Chem. 1975, 97, 159-
165.
(10) Burchat, A. F. M. Sc. Dissertation, University of Waterloo, 1991.
(11) Pearson, W. H.; Lindbeck, A. C.; Kampf, J . W. J . Am. Chem.
Soc. 1993, 115, 2622-2636.
(12) Katritzky, A. R.; Chang, H.-X.; Wu, J . Synthesis 1994, 907-
908.
(13) Pearson, W. H.; Stevens, E. P. Synthesis 1994, 904-906.
(14) Ahlbrecht, H.; Baumann, V. Synthesis 1994, 770-772.
S0022-3263(96)00913-9 CCC: $12.00 © 1996 American Chemical Society

7628 J . Org. Chem., Vol. 61, No. 21, 1996
Ta ble 2. P r ep a r a tion of Am in es 5 fr om Secon d a r y Am id es
Notes
yield of 5 (%)a
entry
R1
R2
yield of 4 (%)a
using LiAlH4
using AlH3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Ph
Ph
Ph
Ph
Ph
Ph
Ph
PhCH2
CH3
Bu
81 (4a )
69 (4b)
88 (4c)
67 (4d )
66 (4e)
65 (4f)
85 (4g)
68 (4h )
92 (4i)
73 (4j)
64 (4k )
67 (4l)
68 (4m )
40 (4n )
51 (4o)
79
84
70
73
41
88
b
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
5k
5l
5m
1
5b
96
91
96
83
86
97
93
84
87
c
91
84
81
90
97
i-Pr
c-C6H11
p-CH3OC6H4CH2
t-Bu
PhCH2
PhCH2
o-CH3C6H4
o-CH3OC6H4
o-CH3OC6H4
b
b
t-Bu
81
b
71
63
36d
61d
CH2CH2CH2
CH3
CH3
H
PhCH2
p-CH3OC6H4CH2
CH3
H
PhCH2
a
b
Yield of isolated, purified (SiO2) product. Reaction not attempted. c Low conversion was observed; amide 4j was recovered in high
d
yield. Yield based on amide 2; see text.
ment of amine 5a with LiAlH4 did not produce any 6 but
returned only starting material, indicating that the Bu3-
Sn group was being cleaved in amide 4a but is stable
once the amide is reduced.
In contrast, reductions with AlH3 gave very clean prod-
ucts in consistently excellent (83-97%) yields. The only
amide which was problematic was N-tert-butyl-o-anis-
amide (4j) (entry 10) which did not react under our
standard conditions (THF, rt, 30 min) or even under more
vigorous ones (THF, reflux, 12 h). Since the related
N-tert-butylbenzamide (4g) (entry 7) and N-benzyl-o-
anisamide (4i) (entry 9) were reduced smoothly with
AlH3, it suggests that the o-methoxy group or the N-tert-
butyl group alone is not detrimental to the reduction but
with both moieties on the same molecule (as in 4j)
reactivity toward AlH3 is considerably diminished. For-
tunately, LiAlH4 reduction of 4j gave the desired amine
5j in good yield.
With formamides (2, R1 ) H), competing O-alkylation
was a problem; the amides 4n and 4o were difficult to
separate from Bu3SnCH2OH21 resulting from O-alkyla-
tion/hydrolysis. In these cases, LiAlH4 reductions were
carried out on unpurified alkylation mixtures; the lower
yields of amines reflect the poor alkylation step and
additional chromatography required to provide pure
amines. When pure samples of amides 4n and 4o were
obtained (by repeated chromatography), alane reduction
provided the expected amines in high yields.
The amount of amine 6 formed with LiAlH4 was
sensitive to the reaction conditions and the order of
addition. When a solution of amide 4a was added to a
solution of LiAlH4 in Et2O (prepared by heating LiAlH4
in Et2O at gentle reflux for 1 hour) at reflux, the ratio of
5a :6 was 14:1 (entry 1); when solid LiAlH4 was added to
a solution of the amide in Et2O and the reaction mixture
was subsequently heated at reflux, the ratio changed to
9.4:1 (entry 2). Much more dramatic was the difference
observed in reactions at 0 °C: addition of amide 4a to
an ethereal solution of LiAlH4 at 0 °C gave a ratio (18:1)
slightly better than the comparable reaction at reflux
temperature (entry 3); however, addition of solid LiAlH4
to a solution of the amide in ether at 0 °C gave a 1:1
mixture of products. Interestingly, amine 6 was the
major product when the reaction was carried out in THF
(entry 5).
We reasoned that an electrophilic reagent such as
DIBAL-H would be less likely to promote this cleavage.
To our dismay, DIBAL-H gave more of the undesired side
product (entries 7, 8). Fortunately, AlH3 (generated in
situ by treatment of LiAlH4 with H2SO4,20 either with or
without removal of the Li salts by centrifugation) effected
a very clean reduction to give amine 5a in 96% yield with
no detectable amount (by 1H NMR spectroscopy) of
N-methylamine 6 (entry 9).
In summary, we have found that competing destan-
nylation occurs when R-amidoorganostannanes are treated
with LiAlH4. Reductions with alane give consistently
high yields of R-aminoorganostannanes. Such reduc-
tions, in combination with alkylations of secondary
amides with Bu3SnCH2I, offer a convenient route to N,N-
disubstituted (aminomethyl)tributylstannanes.
We prepared a series of amides and examined their
reactions with LiAlH4 and AlH3 (Table 2). In general,
alkylations of amides 2 (R1 * H) with Bu3SnCH2I
proceeded smoothly to give amides 4 in reasonable yields
(64-88%). For a series of N-substituted benzamides
(entries 1-6), reductions using LiAlH4 yielded amine 5
in acceptable yields with no clear correlations between
structure and yields. In each case, a byproduct (pre-
sumed to be the corresponding destannylated amine) was
formed which was removed by column chromatography.
Exp er im en ta l Section
All reactions were carried out with dry glassware under an
atmosphere of argon unless otherwise noted. Tributyltin hydride
was prepared according to Szammer and Otvos and was freshly
distilled before use.22 Other reagents were purchased (Aldrich)
or prepared by modification of literature methods; most amides
were prepared by the addition of an acid chloride to an amine
(21) This compound was readily identified by its TLC behavior (Rf
) 0.75 using hex: EtOAc, 2:1; stains blue at rt using phosphomolybdic
acid visualization) and 1H NMR signature (δ 3.99, s, J Sn-H ) 15 Hz).
(22) Szammer, J .; Otvos, L. Chem. Ind. 1988, 726.
(20) (a) Yoon, N. M.; Brown, H. C. J . Am. Chem. Soc. 1968, 90,
2927-2938. (b) Brown, H. C.; Yoon, N. M. J . Am. Chem. Soc. 1966,
88, 1464-1472.

Notes
J . Org. Chem., Vol. 61, No. 21, 1996 7629
under Schotten-Baumann type conditions (aqueous NaOH).
Infrared spectra were recorded as neat liquids between NaCl
plates. 1H and 13C NMR spectra were recorded at 250/63 MHz
using CDCl3 as solvent; tetramethylsilane (1H, δ 0.0) or CDCl3
Anal. Calcd for C24H43NO2Sn: C, 61.78; H, 7.96; N, 2.57.
Found: C, 61.70; H, 7.82; N, 2.58.
N-ter t-Bu tyl-N-[(tr ibu tylstan n yl)m eth yl]ben zam ide (4g):
oil; IR (neat film) 1630, 1582 cm-1
;
1H NMR δ 7.35-7.2 (m, 5
(
13C, δ 77.0) were used as internal references. 1H NMR data
2
H), 3.09 (s, 2 H, J H-Sn ) 25.1 Hz), 1.6-1.2 (m, 12 H), 1.36 (s, 9
H), 1.05-0.75 (m, 15 H); 13C NMR δ 171.2, 140.7, 128.2, 128.0,
126.2, 57.3, 33.5 (317.2, 332.3 Hz), 29.5, 28.8 (19.1 Hz), 27.2 (55.4
Hz), 13.4, 10.27 (306.5, 320.3 Hz); MS (ES) m/z 482 (M + 1, 100).
are presented as follows: chemical shift (multiplicity, integra-
tion, J in Hz). For 13C NMR signals, coupling constants for
satellites due to 117/119Sn (where discernible) are reported in
parentheses in hertz; an asterisk (*) indicates signals that could
be unequivocally attributed to the major rotamer. Mass spectra
were recorded in CH3CN/CH2Cl2 using electrospray ionization
unless otherwise noted; for compounds containing Sn, data are
reported for the most abundant isotope, 120Sn. Elemental
analyses were performed by M-H-W Laboratories, Phoenix, AZ.
Anal. Calcd for
C24H43NOSn: C, 60.02; H, 9.02; N, 2.92.
Found: C, 60.22; H, 8.89; N, 2.94.
N-Be n zyl-N-[(t r ib u t ylst a n n yl)m e t h yl]-2-m e t h ylb e n z-
a m id e (4h ): oil; IR (neat film) 1618, 1250, 1075 cm-1; 1H NMR
δ 7.4-7.1 (m, 9 H), 4.38 (s, 2 H), 2.88 (s, 2 H), 2.34 (s, 3 H),
1.65-1.15 (m, 12 H), 1.05-0.75 (m, 15 H); 13C NMR δ 170.1,
136.6, 136.4, 134.5, 130.4, 128.6, 128.6, 127.5, 127.3, 126.2, 125.7,
55.7, 31.7, 29.1 (27 Hz), 27.4 (57 Hz), 19.3, 13.7, 10.9 (320 Hz);
MS (ES) m/z 530 (M + 1, 100), 472 (18); HRMS (EI) Calcd for
Gen er a l P r oced u r e for th e Alk yla tion of Am id es w ith
(Iod om eth yl)tr ibu tylsta n n a n e. To a cold (0 °C), stirred
solution of the amide (20 mmol) in THF (40 mL) was added
dropwise n-BuLi (13.1 mL of a 1.6 M solution in hexanes, 21
mmol). The solution was stirred at 0 °C for 10 min, and then
DMF (40 mL) and (iodomethyl)tributylstannane (3, 9.48 g, 22
mmol) were added and the mixture was allowed to warm to room
temperature. The reaction was stirred overnight and then
diluted with hexane and water . The mixture was extracted with
hexane, and the organic washings were combined, washed with
brine, dried (MgSO4), and evaporated to yield the crude product
as an oil. Chromatography of the oil on silica gel with hexanes-
EtOAc, 10:1, gave the pure compound.
C
24H34NOSn (M+ - C4H9): 472.1664, found: 472.1645. Anal.
Calcd for C24H43NOSn: C, 63.65; H, 8.20; N, 2.65. Found: C,
63.49; H, 7.96; N, 2.61.
N-Ben zyl-N-[(t r ib u t ylst a n n yl)m et h yl]-2-m et h oxyb en z-
1
a m id e (4i): oil; IR (neat film) 1615, 1247 cm-1; H NMR (500
MHz) δ 7.32-7.21 (m, 5 H), 7.17 (d, 2 H, J ) 7.0 Hz), 6.93 (t, 1
H, J ) 7.5 Hz), 6.86 (d, 1 H, J ) 8.7 Hz), 4.36 (ABq, 2 H, ∆ν )
15.6 Hz, J AB ) 14.1 Hz), 3.78 (s, 3 H), 2.89 (ABq, 2 H, ∆ν ) 29.9
Hz, J AB ) 13.2 Hz), 1.55-1.42 (m, 6 H), 1.31 (sextet, 6 H, J )
7.3 Hz), 0.92 (m, 6 H), 0.88 (t, 9 H, J ) 7.3 Hz); 13C NMR δ
168.4, 155.3, 137.1, 130.0, 128.4, 128.2, 127.4, 127.3, 126.3, 120.7,
110.9, 55.6, 55.1, 32.1, 29.0 (19.7 Hz), 27.4 (56.3 Hz), 13.6, 10.6
(315.7, 330.0 Hz); MS (ES) m/z 546 (M + 1, 100). Anal. Calcd
for C28H43NO2Sn: C, 61.78; H, 7.96; N, 2.57. Found: C, 61.93;
H, 7.80; N, 2.53.
N-Ben zyl-N-[(t r ib u t ylst a n n yl)m et h yl]b en za m id e (4a ):
1
oil; IR (neat film) 1617, 729, 700 cm-1; H NMR δ 7.5-7.1 (m,
2
10 H), 4.51 (s, 2 H), 2.93 (s, 2 H, J H-Sn ) 28 Hz), 1.7-1.2 (m,
12 H), 1.0-0.7 (m, 15 H); 13C NMR δ 170.9, 136.9, 136.3, 129.3,
128.7, 128.4, 127.5, 126.9, 126.8, 56.1, 33.3, 29.0 (19 Hz), 27.4
(56 Hz), 13.7, 10.6 (316, 330 Hz); MS (EI) m/z 514 (M+ - H, 1),
N -t er t -Bu t yl-N -[(t r ib u t ylst a n n yl)m e t h yl]-2-m e t h oxy-
ben za m id e (4j): oil; IR (neat film) 1629, 1585, 871, 753 cm-1
;
458 (100), 105 (69); HRMS (EI) Calcd for C27H41NOSn (M+
C4H9): 458.1508, found: 458.1512. Anal. Calcd for C27H41
-
-
2
1H NMR δ 7.35-6.8 (m, 4 H), 3.83 (s, 3 H), 3.06 (s, 2 H, J H-Sn
) 25 Hz), 1.8-1.1 (m, 12 H), 1.1-0.6 (m, 15 H); 13C NMR δ 167.3,
154.9, 130.5, 129.2, 127.0, 120.3, 110.9, 58.0, 55.2, 32.8, 29.5,
29.0 (18 Hz), 27.4 (56 Hz), 13.6, 10.1 (308, 321 Hz); MS (EI) m/z
NOSn: C, 63.05; H, 8.04; N, 2.72. Found: C, 62.97; H, 7.88; N,
2.71.
N-Meth yl-N-[(tr ibu tylsta n n yl)m eth yl]ben za m id e (4b):
510 (M+ - H, 1), 135 (100), 91 (94); HRMS (EI) Calcd for C21H36
-
oil; IR (neat film) 1611 cm-1; 1H NMR δ 7.40 (s, 5 H), 3.08 (s, 2
NO2Sn (M+ - C4H9): 454.1770, found: 454.1768. Anal. Calcd
21H36NO2Sn: C, 58.84; H, 8.89; N, 2.74. Found: C, 58.87; H,
2
H, J H-Sn ) 20 Hz), 3.00 (s, 3 H), 1.7-1.1 (m, 12 H), 1.09-0.6
C
(m, 15 H); 13C NMR δ 170.0, 136.5, 129.1, 128.2, 127.0, 40.7,
8.67; N, 2.75.
35.5, 29.1 (19 Hz), 27.4 (56 Hz), 13.7, 13.5, 10.4 (314, 327 Hz),
N-[(Tr ibu tylsta n n yl)m eth yl]-2-p yr r olid in on e (4k ): oil; IR
(neat film) 1671 cm-1; 1H NMR δ 3.36 (t, 2 H, J ) 7 Hz), 2.78 (s,
2 H, 2J H-Sn ) 29.3 Hz), 2.35 (t, 2 H, J ) 8 Hz), 1.97 (quint, 2 H),
1.7-1.2 (m, 12 H), 1.1-0.7 (m, 15 H); 13C NMR δ 173.3, 50.9,
30.0, 28.6 (20 Hz), 27.3 (294, 281 Hz), 26.9 (56 Hz), 16.9, 13.2,
10.4 (318, 334 Hz); MS (ES) m/z 390 (M + 1, 100). Anal. Calcd
for C17H35NOSn: C, 52.60; H, 9.09; N, 3.61. Found: C, 52.70;
H, 9.19; N, 3.78.
9.6; MS (ES) m/z 440 (M + 1, 100). Anal. Calcd for C21H37
-
NOSn: C, 57.56; H, 8.51; N, 3.20. Found: C, 57.44; H, 8.38; N,
3.13.
N-Bu tyl-N-[(tr ibu tylsta n n yl)m eth yl]ben za m id e (4c): oil;
IR (neat film) 1613, 1577, 785, 699 cm-1
;
1H NMR δ 7.5-7.3
2
(m, 5 H), 3.35-3.15 (t, 2 H, J ) 7 Hz), 2.95 (s, 2 H, J H-Sn ) 30
Hz), 1.7-1.1 (m, 16 H), 1.1-0.75 (m, 18 H); 13C NMR δ 170.4,
136.8, 128.8, 128.2, 126.5, 52.1, 32.5, 30.5, 29.0 (18 Hz), 27.4
(56 Hz), 19.6, 13.6, 10.6 (331 Hz); MS (ES) m/z 482 (M + 1, 100).
N-Ben zyl-N-[(tr ibu tylsta n n yl)m eth yl]a ceta m id e (4l): oil;
1
IR (neat film) 1636, 1437, 1353, 1241 cm-1; H NMR δ 7.4-7.1
Anal. Calcd for
C24H43NOSn: C, 60.02; H, 9.02; N, 2.92.
(m, 5 H), 4.52 (s, 2 H), 3.05 (s, 0.14 H), 2.78 (s, 1.86 H, 2J H-Sn
30 Hz), 2.14 (s, 3 H), 1.7-1.1 (m, 12 H), 1.05-0.6 (m, 15 H); 13
)
Found: C, 60.20; H, 8.88; N, 3.18.
C
N-Isopr opyl-N-[(tr ibu tylstan n yl)m eth yl]ben zam ide (4d):
oil; IR (neat film) 1608 cm-1; 1H NMR δ 7.5-7.2 (m, 5 H), 4.12-
3.92 (m, 1 H), 2.74 (s, 2 H, 2J H-Sn ) 32 Hz), 1.7-1.25 (m, 12 H),
1.2-1.1 (d, 6 H, J ) 7 Hz), 1.05-0.8 (m, 15 H); 13C NMR: δ
170.0, 137.2, 128.8, 128.4, 126.2, 50.6, 29 (19 Hz), 27.4 (56 Hz),
25.6, 20.4, 13.6, 10.8 (319, 334 Hz); MS (ES) m/z 468 (M + 1,
100). Anal. Calcd for C23H41NOSn: C, 59.25; H, 8.86; N, 3.00.
Found: C, 59.03; H, 8.64; N, 2.98.
NMR δ 169.5, 136.8, 128.8*, 128.5, 128.0, 127.6*, 127.3, 126.5*,
55.5*, 51.0, 34.0, 33.7*, 29.0 (19 Hz), 27.4 (56 Hz), 21.9, 21.0*,
13.7, 10.7; MS (ES) m/z 454 (M + 1, 100). Anal. Calcd for C22
39NOSn: C, 58.43; H, 8.69; N, 3.10. Found: C, 58.09; H, 8.86;
N, 3.04.
N-(4-Meth oxyben zyl)-N-[(tr ibu tylsta n n yl)m eth yl]a cet-
a m id e (4m ): oil; IR (neat film) 1630, 1513 cm-1 1H NMR δ
-
H
;
7.2-7.0 (AA′ of AA′XX′, 2 H), 6.98-6.8 (XX′ of AA′XX′, 2 H),
4.57 (s, 0.08 H), 4.45 (s, 1.92 H), 3.84 (s, 3 H), 3.05 (s, 0.08 H),
2.57 (s, 1.92 H), 2.24 (s, 0.12 H), 2.16 (s, 2.88 H), 1.7-1.1 (m, 12
H), 1.0-0.5 (m, 15 H); 13C NMR δ 169.4, 159.1, 129.4, 128.7,
127.9, 114.2, 113.9, 55.3*, 54.9, 33.5, 29.1 (19 Hz), 27.4, 21.1,
N-Cycloh exyl-N-[(tr ibu tylstan n yl)m eth yl]ben zam ide (4e):
oil; IR (neat film) 2911, 1608, 1449, 1371, 1126, 1072, 943, 893,
814, 697 cm-1 1H NMR δ 7.5-7.2 (m, 5 H), 3.6-3.4 (m, 1 H),
;
2.8 (s, 2 H), 1.9-0.7 (m, 37 H); 13C NMR δ 170.1, 137.1, 128.8,
128.3, 126.1, 59.2, 30.8, 29.1 (19 Hz), 27.4 (56 Hz), 25.4, 25.1,
13.7, 10.7; MS (ES) m/z 484 (M + 1, 100). Anal. Calcd for C23
41NO2Sn: C, 57.28; H, 8.57; N, 2.90. Found: C, 57.27; H, 8.48;
N, 2.91.
-
13.6, 10.7); MS (ES) m/z 508 (M + 1, 100). Anal. Calcd for C26
45NOSn: C, 61.80; H, 8.78; N, 2.77. Found: C, 62.00; H, 8.70;
N, 2.82.
-
H
H
N-Met h yl-N-[(t r ib u t ylst a n n yl)m et h yl]for m a m id e (4n ):
oil; IR (neat film) 1666 cm-1; 1H NMR δ 8.03 (s, 0.1 H), 7.95 (s,
0.9 H), 3.14 (s, 0.3 H), 3.06 (s, 0.2 H), 2.95 (s, 2.7 H), 2.86 (s, 1.8
N-(4-Meth oxyben zyl)-N-[(tr ibu tylsta n n yl)m eth yl]ben z-
a m id e (4f): oil; IR (neat film) 1616, 1248 cm-1; 1H NMR δ 7.5-
7.25 (m, 5 H), 7.11 (d, 2 H, J ) 8.6 Hz), 6.89 (d, 2 H, J ) 8.7
Hz), 4.43 (s, 2 H), 3.80 (s, 3 H), 2.93 (s, 2 H, J H-Sn ) 28 Hz),
1.72-1.12 (m, 12 H), 1.08-0.73 (m, 15 H); 13C NMR δ 170.7,
159.0, 136.4, 129.3, 128.8, 128.4, 128.2, 126.8, 114.1, 55.5, 55.2,
33.0, 29.0 (19 Hz), 27.4 (57 Hz), 13.7, 10.6 (315, 330 Hz); MS
(EI) m/z 544 (M+ - H, 1) , 488 (51), 121 (100); HRMS (EI) Calcd
for C24H34NO2Sn (M+ - C4H9): 488.1613, found: 488.1630.
2
H, J H-Sn ) 30 Hz), 1.7-1.15 (m, 12 H), 1.1-0.7 (m, 15 H); 13C
NMR δ 160.9, 37.7, 30.4, 28.8, 27.1 (56 Hz), 13.4, 10.3*, 9.4; MS
(ES) m/z 364 (M + 1, 19). Anal. Calcd for C15H33NOSn: C,
49.75; H, 9.19; N, 3.87. Found: C, 49.71; H, 9.30; N, 3.94.
N-Ben zyl-N-[(tr ibu tylsta n n yl)m eth yl]for m a m id e (4o):
oil; IR (neat film) 1662 cm-1; 1H NMR δ 8.25 (s, 1 H), 7.45-7.15
(m, 5 H), 4.50 (s, 0.2 H), 4.35 (s, 1.8 H), 2.93 (s, 0.2 H), 2.66 (s,

7630 J . Org. Chem., Vol. 61, No. 21, 1996
Notes
1.8 H, 2J H-Sn ) 27.5 Hz), 1.7-1.1 (m, 12 H), 1.05-0.6 (m, 15 H);
13C NMR δ 162.2, 161.5*, 135.9, 128.6*, 128.4, 127.8, 127.3,
54.7*, 49.0, 28.8 (19.8 Hz), 28.2, 27.1 (57 Hz), 13.5, 10.5* (319,
334 Hz), 9.5; MS (ES) m/z 440 (M + 1, 13), 382 (100). Anal.
Calcd for C21H37NOSn: C, 57.56; H, 8.51; N, 3.20. Found: C,
57.66; H, 8.33; N, 3.21.
[(N -Be n zyl-N -t er t -b u t yla m in o)m e t h yl]t r ib u t ylst a n -
n a n e (5g): oil; IR (neat film) 1458, 1195 cm-1; 1H NMR δ 7.35-
7.15 (m, 5 H), 3.56 (s, 2 H), 2.56 (s, 2 H, 2J H-Sn ) 20.3 Hz), 1.5-
1.15 (m, 12 H), 1.12 (s, 9 H), 0.84 (t, 9 H, J ) 7.0 Hz), 0.69 (m,
6 H); 13C NMR δ 142.5, 128.0, 126.3, 56.8, 55.2, 36.6 (355.8, 372.8
Hz), 29.2 (18.7 Hz), 27.4 (52.1 Hz), 26.7, 13.6, 10.0 (277.6, 290.7
Gen er a l P r oced u r e for th e Red u ction of r-Am id oor ga n o
Sta n n a n es w ith Lith iu m Alu m in u m Hyd r id e. To a cold (0
°C), stirred solution of R-amidoorgano stannane (1 mmol) in Et2O
(15 mL) was added in one portion, solid LiAlH4 (56.9 mg, 1.5
mmol). The reaction mixture was heated to reflux for 30 min,
cooled to room temperature, and quenched with Na2SO4‚
10H2O.23 Solids were removed by filtration through Celite, and
the solvent was evaporated. The residue was subjected to
column chromatography (hexanes-ethyl acetate ) 10:1) to afford
the pure product.
Hz); MS (ES) m/z 468 (M + 1, 100). Anal. Calcd for C24H45
NSn: C, 61.82; H, 9.73; N, 3.00. Found: C, 61.45 ; H, 9.87 ; N,
2.84.
-
[[N-Ben zyl-N-(2-m et h ylb en zyl)a m in o]m et h yl]t r ib u t yl-
sta n n a n e (5h ): oil; IR (neat film) 3026, 2910, 1457 cm-1
;
1H
2
NMR δ 7.4-7.1 (m, 9 H), 3.46 (s, 2 H), 2.56 (s, 2 H, J H-Sn ) 20
Hz), 2.30 (s, 3 H), 1.6-1.2 (m, 12 H), 1.1-0.8 (m, 15 H); 13C NMR
δ 140.1, 137.7, 137.2, 130.2, 129.6, 128.9, 128.2, 126.9, 126.9,
125.7, 62.9 (20 Hz), 20.9 (54 Hz), 19.5, 13.8, 10.3 (283, 297 Hz);
MS (EI) m/z 515 (M+, 4), 224 (90), 105 (100), 91 (25). Anal. Calcd
for C28H45NSn: C, 65.38; H, 8.82; N, 2.72. Found: C, 65.44; H,
8.69; N, 2.83.
Gen er a l P r oced u r e for th e Red u ction of r-Am id oor ga n o
Sta n n a n es w ith Ala n e. To a cold (0 °C), stirred solution of
LiAlH4 (1.0 mL of a 1.0 M solution in THF, 1.0 mmol) in 5 mL
of THF was added H2SO4 (0.5 mL of a 1 M solution in Et2O, 0.5
mmol). The solution was allowed to warm to room temperature
and was stirred for 30 min. The solution was then cooled (0
°C), and the R-amidoorgano stannane (0.5 mmol) was added via
syringe (neat). The reaction mixture was allowed to warm to
room temperature for 30 min and then quenched with Na2SO4‚
10H2O. Subsequent workup and chromatography as described
for reductions with LiAlH4 afforded the indicated products.
[(N,N-Diben zyla m in o)m eth yl]tr ibu tylsta n n a n e (5a ): oil;
IR (neat film) 2955, 1602, 1455 cm-1; 1H NMR δ 7.4-7.2 (m, 10
[[N-Ben zyl-N-(2-m et h oxyb en zyl)a m in o]m et h yl]t r ib u -
tylsta n n a n e (5i): oil; IR (neat film) 1595, 1242 cm-1; 1H NMR
δ 7.52 (d, 1 H, J ) 7.5 Hz), 7.4-7.1 (m, 6 H), 6.93 (t, 1 H, J )
7.4 Hz), 6.80 (d, 1 H, J ) 8.1 Hz), 3.76 (s, 3 H), 3.51 (s, 2 H),
2
3.50 (s, 2 H), 2.61 (s, 2 H, J H-Sn ) 19.9 Hz), 1.6-1.2 (m, 12 H),
1.05-0.75 (m, 15 H); 13C NMR δ 157.7, 140.3, 129.8, 128.6, 128.1,
128.0, 127.4, 126.6, 120.4, 110.2, 62.9 (27.7 Hz), 55.8 (27.1 Hz),
55.1, 43.3 (322.4, 337.3 Hz), 29.2 (19.5 Hz), 27.4 (52.6 Hz), 13.6,
10.1 (283.5, 296.5 Hz); MS (ES) m/z 532 (M + 1, 100). Anal.
Calcd for C28H45NOSn: C, 63.29; H, 8.54; N, 2.64. Found: C,
63.47; H, 8.38; N, 2.64.
2
H), 3.46 (s, 4 H), 2.55 (s, 2 H, J H-Sn ) 23 Hz), 1.6-1.2 (m, 12
H), 1.0-0.7 (m, 15 H); 13C NMR δ 140.0, 128.7, 128.1, 126.8,
62.7 (28 Hz), 42.9, 29.3 (20 Hz), 27.5 (53 Hz), 13.7, 10.1 (287,
300 Hz); MS (EI) m/z 500 (M+ - H, 1.7), 210 (100), 91 (96). Anal.
Calcd for C27H43NSn: C, 64.82; H, 8.66; N, 2.80. Found: C,
65.00; H, 8.46; N, 2.95.
[[N-ter t-Bu tyl-N-(2-m eth oxyben zyl)a m in o]m eth yl]tr ibu -
tylsta n n a n e (5j): oil; IR (neat film) 2957, 2852, 1591 cm-1; 1H
NMR δ 7.60 (d, 1 H, J ) 6.9 Hz), 7.16 (t, 1 H, J ) 7.5 Hz), 6.92,
(t, 1 H, J ) 7.4 Hz), 6.79 (d, 1 H, J ) 8.1 Hz), 3.81 (s, 3 H), 3.59
(s, 2 H), 2.62 (s, 2 H, 2J H-Sn ) 23 Hz), 1.5-1.1 (m, 12 H), 1.12 (s,
9 H), 1.0-0.5 (m, 15 H); 13C NMR δ 157.0, 130.6, 129.0, 126.8,
120.3, 109.5, 55.6, 55.0, 50.6, 37.0, 29.2 (19 Hz), 27.5 (53 Hz),
26.7, 13.7, 9.9 (279, 293 Hz); MS (ES) m/z 498 (M + 1, 100), 454
(78), 332 (82). Anal. Calcd for C25H47NSn: C, 60.50; H, 9.54;
N, 2.82. Found: C, 60.30; H, 9.39; N, 2.70.
[(N-Ben zyl-N-m eth ylam in o)m eth yl]tr ibu tylstan n an e (5b):
oil; IR (neat film) 2955, 1455 cm-1; 1H NMR δ 7.4-7.2 (m, 5 H),
2
3.39 (s, 2 H), 2.5 (s, 2 H, J H-Sn ) 22 Hz), 2.17 (s, 3 H), 1.7-1.2
(m, 12 H), 1.05-0.7 (m, 15 H); 13C NMR δ 139.6, 128.8, 128.1,
126.8, 66.1 (35.5 Hz), 46.4, 46.3, 29.2 (20 Hz), 27.4 (53 Hz), 13.7,
10.0 (288, 302 Hz).
(1-P yr r olid in ylm eth yl)tr ibu tylsta n n a n e (5k ): oil; IR (neat
[(N-Ben zyl-N-bu tyla m in o)m eth yl]tr ibu tylsta n n a n e (5c):
2
film) 2921, 1459, 1377 cm-1
;
1H NMR δ 2.59 (s, 2 H, J H-Sn
)
oil; IR (neat film) 2956, 1457 cm-1
;
1H NMR δ 7.3-7.15 (m, 5
25.2 Hz), 2.48 (unres t, 4 H), 1.81 (m, 4 H), 1.7-1.2 (m, 12 H),
1.1-0.7 (m, 15 H); 13C NMR δ 58.2 (30 Hz), 42.0, 29.1 (19 Hz),
27.3 (54 Hz), 24.2, 13.6, 9.9 (306 Hz); MS (ES) m/z 376 (M + 1,
100). Anal. Calcd for C17H37NSn: C, 54.57; H, 9.97; N, 3.74.
Found: C, 54.33; H, 9.79; N, 3.56.
2
H), 3.42 (s, 2 H), 2.61 (s, 2 H, J H-Sn ) 18 Hz), 2.28 (t, 2 H, J )
7 Hz), 1.7-1.1 (m, 16 H), 1.05-0.7 (m, 18 H); 13C NMR δ 128.7,
128.1, 126.7, 63.7, 58.0, 43.9, 30.5, 29.9, 29.3 (14 Hz), 27.5 (52
Hz), 20.5, 14.1, 13.7, 10.3; MS (ES) m/z 468 (M + 1, 100). Anal.
Calcd for C24H45NSn: C, 61.82; H, 9.73; N, 3.00. Found: C,
61.63; H, 9.63; N, 3.13.
[(N-Ben zyl-N-eth yla m in o)m eth yl]tr ibu tylsta n n a n e (5l):
oil; IR (neat film) 2933, 1646, 1457 cm-1
;
1H NMR δ 7.35-7.2
[(N -Be n zyl-N -isop r op yla m in o)m e t h yl]t r ib u t ylst a n -
n a n e (5d ): oil; IR (neat film) 2929, 1455 cm-1; 1H NMR δ 7.4-
7.2 (m, 5 H), 3.46 (s, 2 H), 2.76 (septet, 1 H, J ) 7 Hz), 2.47 (s,
2 H, 2J H-Sn ) 25 Hz), 1.6-1.2 (m, 12 H), 1.03 (d, 6 H, J ) 7 Hz),
1.2-0.7 (m, 15 H); 13C NMR δ 141.3, 128.5, 128.0, 126.4, 57.3,
52.6, 37.6, 29.3, 27.5 (50 Hz), 17.8, 13.7, 9.6 (291, 305 Hz); MS
(EI) m/z 452 (M+ - H, 2), 162 (100), 91 (98); HRMS (EI) Calcd
for C23H43NSn (M+): 453.2420, found: 453.2417. Anal. Calcd
for C23H43NSn: C, 61.08; H, 9.58; N, 3.10. Found: C, 61.20; H,
9.58; N, 3.13.
2
(m, 5 H), 3.43 (s, 2 H), 2.62 (s, 2 H, J H-Sn ) 19.6 Hz), 2.34 (q,
2 H, J ) 7.1 Hz), 1.7-1.2 (m, 12 H), 1.05 (t, 3 H, J ) 7.1 Hz),
0.95-0.7 (m, 15 H); 13C NMR δ 140.1, 128.7, 128.1, 126.7, 62.6
(28 Hz), 51.1 (28 Hz), 42.5 (337, 358 Hz), 29.3 (20 Hz), 27.5 (53
Hz), 13.7, 12.7, 10.2 (280, 293 Hz); MS (ES) m/z 440 (M + 1,
100). Anal. Calcd for C22H41NSn: C, 60.29; H, 9.43; N, 3.20.
Found: C, 60.44; H, 9.55; N, 3.35.
[[N-Eth yl-N-(4-m eth oxyben zyl)a m in o]m eth yl]tr ibu tyl-
sta n n a n e (5m ): oil; IR (neat film) 2956, 1607 cm-1; 1H NMR δ
7.3-7.15 (AA′ of AA′XX′, 2 H), 6.95-6.75 (XX′ of AA′XX′, 2 H),
[(N -Be n zyl-N -cycloh e xyla m in o)m e t h yl]t r ib u t ylst a n -
1
n a n e (5e): oil; IR (neat film) 2926, 1653, 1453 cm-1; H NMR
2
3.78 (s, 3 H), 3.36 (s, 2 H), 2.62 (s, 2 H, J H-Sn ) 19.4 Hz), 2.32
2
δ 7.4-7.1 (m, 5 H), 3.52 (s, 2 H), 2.54 (s, 2 H, J H-Sn ) 23 Hz),
(q, 2 H, J ) 7.1 Hz), 1.75-1.2 (m, 12 H), 1.15-1.0 (t, 3 H, J )
7.1 Hz), 1.0-0.7 (m, 15 H); 13C NMR δ 158.5, 132.0, 129.8, 113.5,
61.9 (33 Hz), 55.2, 51.6 (35 Hz), 42.4, 29.3 (20 Hz), 27.5 (50 Hz),
13.7, 12.7, 10.3; MS (ES) m/z 470 (M + 1, 100). Anal. Calcd for
2.40-2.25 (m, 1 H), 1.95-0.6 (m, 37 H); 13C NMR δ 141.5, 128.4,
128.1, 128.0, 126.3, 62.6, 57.6, 38.7, 29.2 (19 Hz), 28.8, 27.5 (52
Hz), 26.5, 26.2, 13.7, 9.7; MS (ES) m/z 494 (M + 1, 100), 452
(10). Anal. Calcd for C26H47NSn: C, 63.43, H, 9.62; N, 2.84.
Found: C, 63.39; H, 9.20; N, 2.88.
C
23H43NOSn: C, 58.99; H, 9.26; N, 2.99. Found: C, 58.63; H,
9.36; N, 2.94.
[(N-Ben zyl-N-(4-m et h oxyb en zyl)a m in o)m et h yl]t r ib u -
tylsta n n a n e (5f): oil; IR (neat film) 2955, 1611, 1455 cm-1; 1H
NMR δ 7.4-7.15 (m, 7 H), 6.84 (d, 2 H, J ) 8.7 Hz), 3.77 (s, 3
H), 3.44 (s, 2 H), 3.40 (s, 2 H), 2.54 (s, 2 H, J H-Sn ) 25.5 Hz),
1.7-1.17 (m, 12 H), 1.05-0.7 (m, 15 H); 13C NMR δ 158.6, 140.1,
132.0, 129.8, 128.7, 128.1, 126.7, 113.6, 62.4, 61.9, 55.2, 42.79,
29.2 (19 Hz), 27.5 (53 Hz), 13.7, 10.0 (302 Hz); MS (ES) m/z 532
(M + 1, 100). Anal. Calcd for C28H43NOSn: C, 63.41; H, 8.55;
N, 2.64. Found: C, 63.32; H, 8.73; N, 2.67.
[(N,N-Dim eth yla m in o)m eth yl]tr ibu tylsta n n a n e (1):2 oil;
2
1H NMR δ 2.48 (s, 2 H, J H-Sn ) 22 Hz), 2.21 (s, 6 H), 1.75-1.1
(m, 12 H), 1.08-0.6 (m, 15 H); 13C NMR δ 49.4 (32 Hz), 48.2,
29.7 (20 Hz), 27.3 (54 Hz), 13.5, 9.8 (290, 303 Hz).
Ack n ow led gm en t. We thank the Natural Sciences
and Engineering Research Council (NSERC) of Canada
for financial support of this work.
(23) Treasurywala, A. M. Aldrichim. Acta 1976, 9, 22.
J O9609135