Alternative reagents for the tritylation of alcohols

Article abstract of DOI:10.1080/00397910701357833

Two new tritylation reagents [viz. p-methoxybenzyl trityl ether (p-MBTE) and prenyl trityl ether (PTE)] were prepared. These two new reagents were utilized efficiently for the tritylation of alcohols, using DDQ or 20 mol% DDQ-3 eq. Mn(OAc)3. Copyright Tay

Full text of DOI:10.1080/00397910701357833

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Alternative Reagents for the Tritylation of
Alcohols
Y. Jyothi a , A. K. Mahalingam a , A. Ilangovan a & G. V. M. Sharma a
a Discovery Laboratory, Organic Chemistry Division III , Indian Institute of
Chemical Technology , Hyderabad, India
Published online: 22 Jun 2007.
To cite this article: Y. Jyothi , A. K. Mahalingam , A. Ilangovan & G. V. M. Sharma (2007) Alternative Reagents
for the Tritylation of Alcohols, Synthetic Communications: An International Journal for Rapid Communication
of Synthetic Organic Chemistry, 37:12, 2091-2101
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Synthetic Communicationsw, 37: 2091–2101, 2007
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910701357833
Alternative Reagents for the Tritylation
of Alcohols
Y. Jyothi, A. K. Mahalingam, A. Ilangovan, and
G. V. M. Sharma
Discovery Laboratory, Organic Chemistry Division III, Indian Institute of
Chemical Technology, Hyderabad, India
Abstract: Two new tritylation reagents [viz. p-methoxybenzyl trityl ether (p-MBTE)
and prenyl trityl ether (PTE)] were prepared. These two new reagents were utilized
efficiently for the tritylation of alcohols, using DDQ or 20 mol% DDQ–3 eq.
Mn(OAc)3.
Keywords: p-methoxybenzyl trityl ether (p-MBTE), prenyl trityl ether (PTE)
INTRODUCTION
Discriminative reaction of functional groups of comparable reactivity by
selective protection[1] plays a prominent role in a multistep synthesis of
complex natural products, and seletion of the most suitable protecting group
for each hydroxy function sometimes holds the key to success. The trityl
group, among the several protecting groups that are available, is one of the
most advantageous not only because of its selectivity but because of the
ease of its formation and cleavage. The trityl protecting function is
normally introduced with TrCl in presence of amine;[2] however, several
other reagents such as TrOTMS–TMSTf,[3] tritylated pyridones,[4] BnOTr–
[7]
DDQ,[5] TrODT–TrATC15,[6] and AgoTf–TrCl
are also available.
Recently we have reported[8] the tritylation of alcohols with a new tritylating
agent, p-methoxybenzyl trityl ether (p-MBTE)–DDQ, in the high yields and
Received October 26, 2006
Address correspondence to Y. Jyothi, D-211, Discovery Laboratory, Organic
Chemistry Division III, Indian Institute of Chemical Technology, Hyderabad
500 007, India. E-mail: yjyothi17@rediffmail.com
2091

2092
Y. Jyothi et al.
shorter reaction times, which was found to be better than several existing
methods.
Herein, we report a full account of p-MBTE (1)–DDQ–Mn(OAc)3, an
improved tritylating agent, and prenyl trityl ether (PTE 2)–DDQ– or PTE–
DDQ–Mn(OAc)3–mediated tritylation of alcohols [Eq. (1)].
RESULTS AND DISCUSSION
Preparation of p-Methoxybenzyl Trityl Ether (p-MBTE 1) and Use
as New Tritylating Reagent With DDQ–Mn(OAc)3
Keeping in mind the oxidation potential of p-methoxybenzyl alcohol[9–11] and
hence its reactivity toward DDQ,[12] p-MBTE 1 was prepared by the tritylation
of p-methoxybenzyl alcohol (4) in the presence of Et3N in CH2Cl2 in 93%
yield as a solid, mp 132–1348C (Scheme 1).
Method A: p-MBTE–DDQ-Mn(OAc)3–Mediated Tritylation of
Alcohols
Even though tritylation of alcohols with 1 offers many advantages, the main
drawbacks in the protocol were a) the use of DDQ in stoichiometric
quantity and b) generation of 2,3-dichloro-5,6-dicyanohydrobenzoquinol
(HDDQ) as a side product. To circumvent both these problems, regeneration
of DDQ was felt to be the best alternative. In the present study on the trityla-
tion of alcohols with 1, we have utilized a DDQ regeneration technique,
developed by us earlier[13] using Mn(OAc)3, a transition-metal oxide,[14] as
a mild and potential reoxidant.
Accordingly, reaction of 5 with 1 (1.1 eq) in the presence of 20 mol%
˚
DDQ–3 eq. of Mn(OAc)3 in CH2Cl2 containing molecular sieves 4 A
Scheme 1.

Tritylation of Alcohols
2093
indeed afforded the expected ether 5a in 84% yield, albeit in 6 h. The
study was then extended to other substrates, and the results are tabulated in
Table 1.
Having established 1 and 20 mol% DDQ–3 eq. of Mn(OAc)3 in CH2Cl2
as a better tritylating reagent, the study was then extended to variety of
alcohols, the results of which are shown in Table 1. Thus, compounds 7, 8,
and 11, having primary alcohol groups, underwent tritylation and gave 7a,
8a, and 11a respectively. Similarly, compounds 6 and 10 with secondary
alcohol groups on tritylation with 1 gave 6a (78%) and 10a (81%), respect-
ively. Discriminative tritylation of unsymmetrical diol 9 gave the monotrity-
lated ether 9a (92%) in 10 min, while reaction of symmetrical diol 12 with 1
gave 12a (50%) and 12b (30%) in 20 min. Alcohols 13, 14, and 15 with
different protecting groups (THP, TBS, benzylidene) gave 13a (74%) and
14a (75%) in 10 min and 15a (67%) in 15 min, respectively. Similarly,
amino alcohol 16 and amino acid derivative 17 gave 16a (71%) and 17a
(75%) respectively in 20 min.
The plausible mechanism[15] of DDQ regeneration is illustrated in
Scheme 2. Accordingly, 2 mol of Mn(OAc)3 is reacted with HDDQ and
thus formed intermediate A, leading to DDQ and Mn(OAc)2 by one
electron transfer mechanism.
Thus, in the alternate protocol, regeneration of DDQ using Mn(OAc)3 as
reoxidant solved the problems associated with DDQ and HDDQ. Although the
tritylation reactions with 1 went at a very fast rate and in high yields irrespec-
tive of the nature of alcohols, the main disadvantage associated with p-MBTE
is the formation of anisaldehyde as a by-product. It is well documented in the
literature[16] that allylic double bonds behave similar to benzylic systems
toward oxidation with DDQ. Keeping this in mind, it was planned to
prepare a new tritylating reagent such as prenyl trityl ether (PTE 2) for the
first time. The prenyl group on oxidation produces a low-boiling traceless
counterpart, such as prenal, as a by-product.
Accordingly, prenyl trityl ether (PTE, 2) was prepared by reaction of
prenyl alcohol (13) with TrCl (Scheme 3) in the presence of Et3N and
DMAP (cat.) in CH2Cl2 for 12 h in 65% yield as a colorless syrup, which
1
was characterized by H NMR, IR, and mass spectrometry and used as a
new tritylating reagent for alcohols.
Method C: PTE–DDQ–Mediated Tritylation of Alcohols
˚
Initially, 5 was treated with 2 and DDQ in the presence of activated MS 4 A in
CH2Cl2 [Eq. (1)] for 20 min to give trityl ether 5a in 88% yield. Encouraged by
this expected result, this study was extended to various alcohols. Thus, menthol
6 underwent tritylation in 40 min with 80% yield to give 6a, while sugar deriva-
tives 8–11 on tritylation gave the products 8a (79%), 9a (81%), 10a (89%), and
11a (84%) in 20–40 min. Symmetric diol 12 on reaction with 2 gave 12a (80%)
and 12b (8%) in 15 min, whereas unsymmetric diol 9 gave 9a (81%) as an

Table 1. Tritylation of alcohols with different reagents
Method A
Method B
Method C
Entry no.
1
Starting materials
Products
Time (h)
Yield (%)
84
Time (min)
Yield (%)
88
Time (h)
Yield (%)
74
6
20
40
8
8
2
14
78
80
75
3
4.5
82
10
84
—
—
4
5
5
4
86
79
20
20
79
81
6
5
76
74

6
18
81
80
40
89
84
—
—
79
7
8
8
6
20
15
8
5
50
30
74
80
8
75
10
74
9
6
6
20
20
84
7
7
10
75
67
83
76
75
67
11
4
20
3
12
13
8
8
71
75
30
30
81
80
8
8
78
72

2096
Y. Jyothi et al.
Scheme 2. Preparation of prenyl trityl ether (PTE-2) and use as new tritylating reagent.
Scheme 3.
exclusive product in 20 min. Alcohols 13, 14, and 15 with acid-sensitive pro-
tecting groups (THP, TBS, benzylidene) gave 13a (84%), 14a (83%), and 15a
(76%), respectively, in 20 min, whereas aminol 16 and amino acid derivative
17 afforded 16a (81%) and 17a (80%) in 30 min, respectively.
Method D: PTE–DDQ Mn(OAc)3–Mediated Tritylation of Alcohols
Thus, even though the reactivity of the new tritylating reagent 2 was found to
be comparable to 1 and formation of anisaldehyde could successfully be
avoided, still it utilizes a stoichiometric quantity of DDQ and generates 2,3-
dichloro-5,6-dicyanohydrobenzoquinol (HDDQ) as by-product. To improve
the usability of 2 for the tritylation and to circumvent this problem, the trityla-
tion in the present study was also achieved with 20 mol% DDQ–3 eq.
Mn(OAc)3 by a regeneration technique.
Accordingly, 5, on reaction with 2, Mn(OAc)3 (3 eq), and DDQ
(20 mol%) in CH2Cl2, gave 5a (74%), albeit in 8 h. similar result were
obtained with all other substrates as summarized in Table 1. Thus, even
though the reaction by the DDQ regeneration method was slow, the yields
were good and it avoided the formation of HDDQ. Thus, the new reagent 2
is as efficient as p-MBTE in tritylation; although unlike 1, the by-product
prenal is traceless because it is easy to remove during workup.
CONCLUSION
The present study thus demonstrates a) the preparation of new tritylating
reagent p-MBTE 1 and its use for the tritylation of alcohols with DDQ of
DDQ–Mn(OAc)3, where use of stoichiometric quantity of DDQ is avoided

Tritylation of Alcohols
2097
in addition to the by-product quinol, and b) a modified tritylating reagent PTE
2 is synthesized and utilized under DDQ and DDQ regeneration conditions for
the tritylation, wherein the formation of by-product such as anisaldehyde is
also avoided. Thus, because their ease of preparation and simple and
efficient reaction conditions for protection, the alternative tritylating agents
could find immense use in organic systhesis.
EXPERIMENTAL
General
NMR spectra were recorded on Varian Gemini FT-200 MHz (218C) with 7- to
10-mM solutions in appropriate solvents using TMS as internal standard.
Solvents were dried over standard drying agents and were freshly distilled
prior to use. IR spectra were taken with a Perkin-Elmer 1310 spectrometer.
Mass spectra were recorded on CEC-21-11013 or Finnigan Mat 1210
double-focusing mass spectrometers operating at a direct inlet system, and
FABMS was measured using a VG AUTOSPEC mass spectrometers at 5 or
7 K resolution using perflurokerosene as an internal reference. Nomenclature
mentioned in this section was adopted from ACD/Name Version 1.0b,
Advanced Chemistry Development Inc., Toronto, Canada. Organic solutions
were dried over anhydrous Na2SO4 and concentrated below 408C in vacuo.
Elemental analysis was recorded on Elementar (Vario El, Germany).
Procedure for the Preparation of the Reagents
Preparation of p-Methoxybenzyl Trityl Ether (p-PMBTE 1)
To a stirred solution of p-methoxybenzyl alcohol (4, 5.0 g, 36.2 mmol) and
˚
Et3N (3.65 g, 36.2 mmol) in CH2Cl2 (50 mL) containing activated MS 4A
(1.5 g) at room temperature, trityl chloride (10.06 g, 36.2 mmol) and
4-dimethylamonopyridine (0.440 g, 3.62 mmol) were added. After 8 h, the
reaction mixture was evaporated, the residue was dissolved in ethyl acetate
(20 mL), and the insoluble materials were filtered. After evaporation of the
solvent, the residue was purified by column chromatography (silica gel,
toluene) to afford 1 (12.8 g) in 93% yield as a white solid, mp 132–1348C.
Analysis found C, 85.21; H, 6.34. C27H24O2 requires C, 85.23; H, 6.36%.
dH (200 MHz, CDCl3) 3.8 (s, 2H, CH2Ar), 4.18 (s, 3H, OCH3), 7.15–7.55
(m, 19H, ArH); m/z: (FABMS) 243 (Mþ-137).
Preparation of Prenyl Trityl Ether (PTE 2)
To a stirred solution of prenyl alcohol (13, 3.0 g, 34.9 mmol) and Et3N (3.87 g,
˚
38.3 mmol) in CH2Cl2 (40 mL) containing activated MS 4A (1.5 g) at room

2098
Y. Jyothi et al.
temperature, trityl chloride (9.7 g, 34.9 mmol) and 4-dimethylaminopyridine
(0.42 g, 3.49 mmol) were added. After 12 h, it was worked up as described
for 1 and was purified by column chromatography (silica gel, EtOAc–
hexane, 1:9) to afford 2 (7.41 g) in 65% yield as a colorless syrup. Analysis
found C, 87.72; H, 7.34. C24H24O requires C, 87.76; H, 7.37%. dH
(200 MHz, CDCl3) 1.50, 1.75 (2s, 6H, -CH3), 3.55 (d, 2H, J ¼ 6.8 Hz,
H-1), 5.40 (t, 1H, J ¼ 5.9 Hz, H-2), 7.15–7.55 (m, 15H, Ar-H), m/z:
(FABMS) 328 (Mþ).
General Procedure for the Preparation of Trityl Ethers
DDQ Method
A solution of alcohol (1.0 mmol) and reagent 1 or 2 (1.1 mmol) in CH2Cl2
˚
(3 mL) containing activated MS 4A (250 mg) was treated with DDQ
(1.5 mmol) and stirred at room temperature. After the completion of
reaction (TLC analysis), it was quenched with saturated NaHCO3 solution
(10 mL) and extracted with CHCl3 (3 ꢀ 10 mL). The organic layer was
dried (Na2SO4) and evaporated and the residue was purified by column chrom-
atography (silica gel, EtOAc in hexane) to afford trityl ethers.
DDQ–Mn(OAc)3 Method
A solution of alcohol (1.0 mmol) and reagent 1 or 2 (1.1 mmol) in CH2Cl2
˚
(5 mL) containing activated MS 4 A (250 mg) and Mn(OAc)3 (3.0 mmol)
was treated with DDQ (0.2 mmol) and stirred at room temperature. After
the completion of reaction (TLC analysis), the solid was filtered and
washed with CHCl3 (25 mL). The filtrate was quenched with saturated
NaHCO3 solution (10 mL) and extracted into CHCl3 (3 ꢀ 10 mL). The
organic layer was dried (Na2SO4) and evaporated and the residue was
purified by column chromatography (silica gel, EtOAc in hexane) to afford
trityl ethers.
Data
1-Trityloxy-4-phenylbutane (5a)
Syrup; method A: 6 h, 84%. Analysis found C, 88.75; H, 7.18. C29H28O
requires C, 88.73; H, 7.19%. gmax 3400, 3100, 2920, 2850, 1800, 1500,
1050, 760 cm21; dH (200 MHz, CDCl3) 1.65–1.90 (m, 4H), 2.64 (t, 2H,
J ¼ 7.6 Hz), 3.12 (t, 2H, J ¼ 6.12 Hz), 7.1–7.5 (m, 20H); m/z: (FABMS)
391 (mþ-1, 8%), 315 (mþ-77, 20%), 243 (100%); method B: 20 min, 88%;
method C: 8 h, 74%.

Tritylation of Alcohols
2099
(1S,2R,4S)-1-Isopropyl-4-methyl-2-(trityloxy) Cyclohexane (6a)
Semisolid; method A: 14 h, 78%. Analysis found C, 87.13; H, 8.49. C29H34O
requires C, 87.39; H, 8.60%. gmax 3350, 3100, 2900, 2850, 1590, 1450, 1390,
1200, 1100, 760 cm21; dH (200 MHz, CDCl3) 0.22 (d, 2H, J ¼ 7.0 Hz), 1.0–
2.60 (m, 11H), 1.45–1.65 (m, 4H), 2.40–2.50 (m, 1H), 2.70–2.85 (m, 1H),
7.12–7.55 (m, 15H); m/z: (FABMS) 398 (Mþ), 259 (10%); method B:
40 min, 80%; method C: 8 h, 75%.
(2Z,4S)-4,5-Isopropylidenedioxy-1-trityloxy-pent-4-en (7a)
Syrup; method A: 4.5 h, 82%. Analysis found C, 80.81; H, 7.01. C27H28O3
requires C, 80.97, H, 7.05%. gmax 3500, 2900, 2550, 2420, 1590, 1450,
1180, 1150, 1080, 900, 780 cm21; dH (200 MHz, CDCl3) 1.3, 1.38 (2s, 6H),
3.45 (t, 1H, J ¼ 10.2, 9.69 Hz), 3.55–3.98 (m, 3H), 4.59 (q, 1H, J ¼ 9.18,
9.69 Hz), 5.48–5.62 (m, 1H), 5.72–5.92 (m, 1H), 7.25–7.50 (m, 15H);
m/z: (FABMS) 259 (Mþ-141), 243 (100%); method B: 10 min, 84%.
1,2:3,4-Di-O-isopropylidene-6-O-trityl-a-D-galactopyranose (8a)
Syrup; method A: 5 h, 86%. Analysis found C, 74.05; H, 6.80. C31H34O6
requires C, 74.08; H, 6.82%. gmax 3400, 2860, 1800, 1550, 1450, 1200,
1150, 1080, 800, 760, 680 cm21; dH (200 MHz, CDCl3) 1.32, 1.35, 1.39,
1.56 (4s, 12H), 3.20–3.28 (m, 2H), 3.92 (t, 1H, J ¼ 5.72, 6.66 Hz). 4.22–
4.30 (m, 2H), 4.55 (dd, 1H, J ¼ 2.85, 3.80 Hz), 5.45 (d, 1H, J ¼ 4.76 Hz),
7.20–7.50 (m, 15H); m/z: (FABMS) 503 (Mþ þ 1); method B: 20 min,
79%; method C: 6 h, 76%.
1,2-O-Isopropylidene-5-O-trityl-a-D-xylofuranose (9a)
Syrup; method A: 4 h, 79%. Analysis found C, 74.99; H, 6.55. C27H28O5
requires C, 74.98; H, 6.53%. gmax 3480, 3100, 3080, 2950, 1950, 1790,
1550, 1350, 1280, 1150, 1050, 760 cm21; dH (200 MHz, CDCl3) 1.3, 1.45
(2s, 6H), 3.10 (br, s, 1H), 3.40–3.62 (m, 2H), 4.22 (br, s, 1H), 4.98 (d, 1H,
J ¼ 4.76 Hz), 5.99 (d, 1H, J ¼ 4.76 Hz), 5.99 (d, 1H, J ¼ 4.76 Hz), 7.20–
7.48 (m, 15H); m/z: (FABMS) 455 (Mþ þ 23), 243 (100%); method B:
20 min, 81%; method C: 5 h, 74%.
1,2-O-Isopropylidene-3-O-benzyl-6-ene-5-O-trityl-a-D-xylofuranose (10a)
Semisolid; method A: 18 h, 81%. Analysis found C, 78.79; H, 6.63. C36H36O5
requires C, 78.81; H, 6.61%. gmax 3500, 2850, 1690, 1500, 1400, 1180, 1000,
780 cm21; dH (200 MHz, CDCl3) 1.48, 1.30 (2s, 6H), 3.72 (d, 1H,
J ¼ 4.1 Hz), 3.95 (dd, 1H, J ¼ 2.70, 7.60 Hz), 4.74–4.32 (m, 6H),

2100
Y. Jyothi et al.
5.62–5.42 (m, 1H), 5.85 (d, 1H, J ¼ 4.1 Hz), 7.58–7.10 (m, 20H); m/z:
(FABMS) 533 (Mþ-15); method B: 40 min, 89%.
Methyl 2,3-O-Isopropylidene-5-O-trityl-a-D-ribofuranose (11a)
Semisolid; method A: 8 h, 80%. Analysis found C, 75.30; H, 6.75. C28H30O5
requires C, 75.31; H, 6.77%. gmax 3450, 2900, 1800, 1750, 1550, 1400, 1250,
1160, 1090, 1000, 890, 780 cm21; dH (200 MHz, CDCl3) 1.30, 1.48 (2s, 6H),
3.05–3.15 (m, 5H), 4.32 (t, 1H, J ¼ 6.9 Hz), 4.38 (d, 1H, J ¼ 5.7 Hz), 4.55
(d, 1H, J ¼ 5.7 Hz), 4.88 (s, 1H), 7.15–7.55 (m, 15H); m/z: (FABMS) 431
(Mþ-15); method B: 20 min, 84%; method C: 8 h, 79%.
Tritylation of 1,6-Hexandiol
Syrup; method A: 6 h, first eluted was 1-trityloxy hexane-6-ol (12a, 50%).
Analysis found C, 83.26; H, 7.85. C25H28O2 requires C, 83.29; H, 7.83%.
gmax 3400, 2860, 1620, 1580, 1350, 1210, 1100, 950, 790 cm21; dH
(200 MHz, CDCl3) 1.20–1.73 (m, 8H), 3.02 (t, 2H, J ¼ 6.9 Hz), 3.58
(t, 2H, J ¼ 6.5 Hz), 7.12–7.48 (m, 15H), m/z: (FABMS) 383 (Mþ þ 23);
second eluted was 1,6-ditrityloxy hexane (12b, 30%). Analysis found C,
87.65; H, 7.01. C44H42O2 requires C, 87.67; H, 7.02%. gmax 3450, 2950,
2900, 2820, 1580, 1210, 1100, 900, 780 cm21; dH (200 MHz, CDCl3)
1.25–1.45 (m, 4H), 1.54–1.70 (m, 4H), 3.02 (t, 4H, J ¼ 6.9 Hz), 7.15–7.48
(m, 30H); m/z: (FABMS) 359 (Mþ-243); method B: 15 min, (12a, 80%),
(12b, 8%); method C: 5 h, (12a, 75%), (12b, 10%).
1-Tetrahydro-2H-pyranlyoxy-6-trityloxyhexane (13a)
Syrup; method A: 6 h, 74%. Analysis found C, 81.02; H, 8.12. C30H36O3
requires C, 81.04; H, 8.16%. gmax 3450, 2950, 2900, 2820, 1580, 1210,
1100, 900, 780 cm21; dH (200 MHz, CDCl3) 1.2–1.85 (m, 14H), 3.05 (t, 2H,
J ¼ 6.4 Hz, H-1), 3.25–3.50 (m, 2H, H-6), 3.55–3.90 (m, 2H, H-50)þ, 4.55
(brs, 1H, H-10), 7.1–7.50 (m, 15H, Ar-H); m/z: (FABMS) 359 (M -85);
method B: 20 min, 84%; method C: 7 h, 74%.
1-Trityloxy-6-tert-butyldimethylsilyloxyhexane (14a)
Syrup; method A: 6 h, 74%. Analysis found C. 78.40; H, 8.89. C31H42O2Si
requires C, 78.43; H, 8.92%. gmax 3450, 3110, 2880, 1610, 1550, 1210,
1100, 810, 780 cm21; dH (200 MHz, CDCl3) 0.05 (s, 6H), 0.9 (s, 9H), 1.2–
1.7 (m, 8H), 3.05 (t, 2H, J ¼ 6.0 Hz, H-1), 3.60 (t, J ¼ 6.0 Hz, H-6), 7.15–
7.50 (m, 15H, Ar-H), m/z: (FABMS) 417 (Mþ-57); method B: 20 min,
84%; method C: 7 h, 74%.

Tritylation of Alcohols
2101
(2R,3S)-1,3-Benzylidenedioxy-2-hydroxy-5-trityloxy-pentane (15a)
Syrup; method A: 4 h, 67%. gmax 3450, 3100, 2920, 2840, 1550, 1400, 1300,
1210, 1100, 900 cm21; dH (200 MHz, CDCl3) 1.75 (m, 2H), 3.16 (t, 2H,
J ¼ 11.40 Hz), 3.50 (m, 3H), 4.24 (m, 1H) 5.38 (s, 1H), 7.26 (m, 15H, Ar-
H), 7.44 (m, 5H, Ar-H), m/z (FABMS); method B: 20 min, 76%; method
C: 3 h, 67%.
tert-Butoxycarbonyl-1-phenyl-3-trityloxy-2-propanamine (16a)
Syrup; method A: 8 h, 71%. gmax 3520, 3100, 2950, 1750, 1520, 1400, 1180,
1050, 720 cm21; dH (200 MHz, CDCl3) 1.41 (s, 9H, -BoC), 2.90 (d, 1H,
J ¼ 8.69 Hz), 3.07 (m, 1H), 3.70 (m, 1H), 4.74 (d, 1H, J ¼ 17.4 Hz), 7.22
(m, 15H, Ar-H), 7.41 (m, 5H, Ar-H); m/z (FABMS) 380 (Mþ-100); method
B: 30 min, 81%; method C: 8 h, 78%.
tert-Butoxycarbonyl-2-methylamino-3-trityloxy Propanoate (17a)
Syrup; method A: 8 h, 75%. gmax 3500, 3100, 2950, 1800, 1550, 1400, 1200,
1100, 810, 780 cm21; dH (200 MHz, CDCl3) 1.44 (s, 9H, -BoC), 3.38 (dd, 1H,
J ¼ 7.14, 14.28 Hz), 3.50 (dd, 1H, J ¼ 7.14, 14.28 Hz), 3.72 (s, 3H, -CH3),
4.38 (m, 1H, J ¼ 17.80 Hz), 5.38 (d, 1H, J ¼ 17.80 Hz), 7.24 (m, 15H, Ar-
H); m/z (FABMS) 384 (Mþ-77); method B: 30 min, 80%; method C: 8 h,
72%.
REFERENCES
1. Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic Synthesis, 2nd ed.;
John Wiley and Sons Inc.: New York, 1991.
2. Hanessian, S.; Staub, A. P. A. Tertrahedron Lett. 1973, 14, 3555.
3. Murata, S.; Noyori, R. Tetrahedron Lett. 1981, 22, 2107.
4. Effenberger, F.; Brodt, W.; Zinczuk. J. Chem. Ber. 1983, 116, 3011.
5. Oikawa, M.; Yoshizaki, H.; Kusumoto, S. Synlett 1998, 757.
6. Christina, E. I.; Scott, M. R.; James, E. H. Langmiur 2004, 20, 9144.
7. Joseph, T.; Lundquist, A. D., IV; Satterfield, J. C. P. Org. Lett. 2006, 8, 3915.
8. Sharma, G. V. M.; Mahalingam, A. K.; Prasad, T. R. Synlett 2000, 1479.
9. Turner, A. B. Synthetic Reagents, Pizey, J. S. and Harwood, E. (Eds.); Vol. 3, 193.
10. Lund, H. Acta Chem. Scand. 1957, 11, 491.
11. Zweig, A.; Hodgson, W. G.; Jura, W. H. J. Am. Chem. Soc. 1964, 86, 4124.
12. Horita, K.; Yoshika, T.; Oikawa, Y.; Yonemitsu, O. Tetrahedron Lett. 1986, 27,
3021.
13. Sharma, G. V. M.; Lavanya, B.; Mahalingam, A. K.; Radha Krishna, P. Tetrahe-
dron Lett. 2000, 41, 10323.
14. Snider, B. B. Chem. Rev. 1996, 96, 339.
15. Burstein, S. H.; Ringold, H. J. J. Am. Chem. Soc. 1964, 86, 4952.
16. Lewis, R. N.; Wright, J. R. J. Am. Chem. Soc. 1952, 74, 1253.