Sugar-Pirating as an Enabling Platform for the Synthesis of 4,6-Dideoxyhexoses

Article abstract of DOI:10.1021/jacs.9b13766

An efficient divergent synthetic strategy that leverages the natural product spectinomycin to access uniquely functionalized monosaccharides is described. Stereoselective 2′- and 3′-reduction of key spectinomycin-derived intermediates enabled facile acces

Full text of DOI:10.1021/jacs.9b13766

Subscriber access provided by BIU Pharmacie | Faculté de Pharmacie, Université Paris V
Article
Sugar-pirating as an enabling platform
for the synthesis of 4,6-dideoxyhexoses
Yinan Zhang, Jianjun Zhang, Larissa V Ponomareva, Zheng Cui, Steven G. Van Lanen, and Jon S Thorson
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.9b13766 • Publication Date (Web): 24 Apr 2020
Downloaded from pubs.acs.org on April 25, 2020
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a service to the research community to expedite the dissemination
of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in
full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully
peer reviewed, but should not be considered the official version of record. They are citable by the
Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore,
the “Just Accepted” Web site may not include all articles that will be published in the journal. After
a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web
site and published as an ASAP article. Note that technical editing may introduce minor changes
to the manuscript text and/or graphics which could affect content, and all legal disclaimers and
ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or
consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W.,
Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 7
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
Sugar-Pirating as an Enabling Platform for the Synthesis of 4,6-
Dideoxyhexoses
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Yinan Zhang,†,‡,§ Jianjun Zhang,‡,§ Larissa V. Ponomareva,‡ Zheng Cui,⁋ Steven G. Van Lanen,⁋ Jon S.
⁋
Thorson‡, ,*
†Jiangsu Key Laboratory for Functional Substance of Chinese Medicine, School of Pharmacy, Nanjing University of
Chinese Medicine, Nanjing, Jiangsu, 210023, China
‡Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, Ken-
tucky 40536, USA
⁋
Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536,
USA
Supporting Information Placeholder
ABSTRACT: An efficient divergent synthetic strategy that leverages the natural product spectinomycin to access uniquely func-
tionalized monosaccharides is described. Stereoselective 2’- and 3’-reduction of key spectinomycin-derived intermediates enabled
facile access to all eight possible 2,3-stereoisomers of 4,6-dideoxyhexoses as well as representative 3,4,6-trideoxysugars and 3,4,6-
trideoxy-3-aminohexoses. In addition, the method was applied to the synthesis of two functionalized sugars commonly associated
with macrolide antibiotics – the 3-O-alkyl-4,6-dideoxysugar D-chalcose and the 3-N-alkyl-3,4,6-trideoxysugar D-desosamine.
fers the potential to circumvent redundant multi-step protecting-
1. INTRODUCTION
Deoxygenated and/or uniquely functionalized sugars are a signa-
ture of many clinically relevant bioactive microbial natural prod-
group manipulations that often hamper classical preparative
methods.8 Inspired by the recovery of select uniquely-
functionalized sugars from natural product acid hydrolysis (e.g.,
ucts.1 Within this context, 4,6-dideoxyhexoses (Figure 1A) can
D-desosamine from erythromycin,5a L-noviose from novobiocin,9),
play a key role in macrolide antibiotic pharmacokinetics, pharma-
codynamics and molecular target recognition.2 Thus, an array of
elegant synthetic strategies to access deoxygenated and/or unique-
ly functionalized monosaccharides, including 4,6-deoxyhexoses,
have been developed (Figure 1B). Representative examples in-
clude classical linear routes for deoxygenation of monosaccha-
rides,3 de novo synthesis from accessible chiral starting precur-
sors,4 and, to a lesser extent, direct recovery from natural products
via chemical hydrolysis.5 Yet, practical systematic synthetic ap-
proaches to access 4,6-dideoxyhexoses are lacking and there is a
disparity in synthetic efficiencies of existing methodology as ex-
emplified by the syntheses of 4,6-dideoxy-glucose (5 steps, 20%
yield),5d 4,6-dideoxy-mannose (7 steps, 24% yield),3b 4,6-
dideoxy-allose (11 steps, 5% yield),3a 4,6-dideoxy-3-amino-
glucose (4 steps, 29%),6c D-chalcose (7 steps, 5% yield)4a and D-
desosamine (de novo synthesis 5-10 steps, 15-27% yield; hydroly-
sis from erythromycin 1 step, 25% yield).6a-c As a conceptual
extension of exploiting a natural product glycosides for semi-
synthesis (i.e., sugar pirating), herein we describe the use of spec-
tinomycin to enable rapid access to 4,6-dideoxyhexoses with all
possible 2,3-configurations as well as related methoxy-4,6-
dideoxysugars, trideoxyaminosugars, and trideoxysugars. The
proof-of-concept platform described herein enabled the divergent
synthesis of twelve deoxysugars in 4-7 steps with overall isolated
yields ranging from 12-58% starting from spectinomycin (Scheme
1).
Figure 1. (A) Representative 4,6-dideoxysugar-containing
macrolides and (B) schematic comparison of prior approaches
Semi-synthesis is an expedient synthetic and biosynthetic ap-
proach to prepare targets of interest from accessible natural prod-
and current method to synthesize 4,6-dideoxysugars.
ucts.7 In the context of glycosides, a semi-synthesis platform of-
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 2 of 7
Table 1. Diastereoselective reduction of 3’-ketone of
protected spectinomycin (1)a
1
2
3
4
5
6
7
8
9
temp,
time
rt, 30
min
dr ratio
Yields of
3a, 3bc
90% (3a-
Boc)
entry
1
R
conditions
(3a:3b)b
NaBH4,
MeOH
Boc
>10:1
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Rhodium,
H2, AcOH,
MeOH-H2O
NaBH4,
2
H
rt, 3h
<1:10
95% (3b)
3
4
5
Cbz
rt, 2h
4:1
3:1
1:1
ND
ND
ND
MeOH
Cbz LiBH4, THF rt, 2h
BH3·Me2S,
Cbz
rt, 3h
THF
BH3·Me3N,
HCl, EtOH
NaCNBH3,
AcOH,
EtOH
pico-
line·BH3
complex,
MeOH
6
7
Cbz
rt, 3h
1:1
ND
ND
Scheme 1. Schematic overview of divergent 4,6-
deoxysugar synthesis from spectinomycin. Final depro-
tection strategies are highlighted in Table 5.
Cbz
Cbz
Cbz
rt, 2h
rt, 2h
1:1.3
we envisioned a suitable natural product might serve as enabling
synthetic precursor template for the divergent synthesis of sets of
uniquely-functionalized monosaccharides (Figure 1B). To test this
hypothesis, spectinomycin was selected based on the unique
pseudo di-keto glycoside structure, anticipated atom economy
(50%, Wdeoxy-glycoside moiety/Wspectinomycin), commercial availability
(~$14 per gram from Sigma-Aldrich) and potential for divergent
access to various 4,6-deoxyhexoses (Scheme 1).
8
9
1:1
ND
LiAl-
(OtBu)3H,
THF
-78 oC,
3h
95% (3a-
Cbz)
>10:1
aAll reactions were carried out with 0.05 mmol 1 and 0.2
mmol reducing agent under specific conditions. bThe dr ratios
of crude reaction products determined by proton NMR. Iso-
lated yields with scale-up reactions (5-10 mmol 1) where ND
2. RESULTS AND DISCUSSION
c
Stereoselective reduction of the spectinomycin 3’-carbonyl was
conducted in the presence or absence of 1,3-diamino-protecting
groups (Table 1). For the former, 1,3-diamino-Boc protection
followed by standard reduction with sodium borohydride provided
the desired 3’--hydroxy product 3a in 90% yield (dr > 10:1, 2
steps).10 Alternatively, evaluation of reduction conditions with
1,3-diamino-Cbz-protected spectinomycin11 revealed efficient
conversion to the desired 3’--hydroxy species using
LiAlH(OtBu)3 under kinetic control (95%, dr > 10:1).12 For the
latter, catalytic hydrogenation of spectinomycin as previously
reported by Rosenbrook,13 followed by 1,3-diamino-Boc-
protection, gave the desired 3’--hydroxy product 3b in 89%
yield (dr > 10:1, 2 steps).
reflects not determined due to poor stereoselectivity.
Scheme 2. Stereoselective reduction of 3b 2’-
hemiacetal.a
explored within the context of 3’--hydroxy substrate 3b (Scheme
2). This study revealed sodium cyanoborohydride to afford the
desired 2’-equatorial product 5c (allose-type, 80% yield, >10:1
eq/ax ratio) and lithium borohydride to favor the 2’-axial product
5d (altrose-type, 71% yield, 6:1 ax/eq).
As summarized in Table 2, borohydride reagents were found to be
the only reagents from those screened capable of advancing 3a/3b
2’-hemiacetal reduction (entries 1-11). Beginning with 3’--
hydroxy substrate 3a, sodium cyanoborohydride was found to
favor the desired 2’-equatorial product 5a (glucose-type, 49%
yield, 3:1 eq/ax ratio). The presence of Brønsted acids (entries 12-
13) led to further improvements with sterically hindered pivalic
acid in ethanol identified as the best conditions (61% yield, 3:1
eq/ax ratio). Increased temperature had little effect on the yield or
stereoselectivity but improved reaction time (entry 14). Lithium
borohydride favored the desired 2’-axial product 5b-Boc (man-
nose-type), where elevated temperatures and corresponding re-
duced reaction times led to improved yields but poor stereoselec-
tivity (e.g., entry 2 versus entry 15). Importantly, the use of dia-
mino-Cbz-protected precursor (entries 16 and 17) under similar
conditions led to diamino-Cbz-protected 5b-Cbz in good yield
with improved stereoselectivity (75% yield, 5:1 ax/eq ratio). The
optimized conditions for 3a 2’-hemiacetal reduction were next
Guided by the key 2’- and 3’-stereoselective reduction principles
developed for 4,6-dideoxyhexoses, efforts were next directed to
assessing platform utility for the synthesis of deoxyaminosugars
(Scheme 3). The central intermediate 3’--amino spectinomycin
4a was produced from 1,3-diamino-Boc-protected spectinomycin
via reductive hydrogenation of the corresponding 3’-E-oxime 2 (2
steps, 65% yield).14 In contrast, despite testing an extensive array
of reduction conditions and reagents, no suitable route was identi-
fied to advance the 3’-oxime to the corresponding 3’--amino
precursor 4b. However, reinvestigation/optimization of previously
reported reductive amination conditions15 toward improving stere-
oselectivity and prohibiting 3’-hydroxy byproduct production
(Table 3, entry 1 versus entry 4), led to the desired 4b (71% yield,
dr 10:1). Following the conditions developed for the stereoselec-
tive reduction of the 3a/3b 2’-hemiacetal, similar outcomes
(yields of 62-78%, eq/ax ratios ranging from 3:1 to >10:1) were
ACS Paragon Plus Environment

Page 3 of 7
Journal of the American Chemical Society
Table 2. Stereoselective reduction of 3a 2’-hemiacetal.a
Table 3. Diastereoselective reductive amination of in-
termediate 1-Boc.a
1
2
3
4
5
6
7
8
9
eq/ax
ratiob
rt 24h 1:1
entry
conditions
NaBH4, MeOH
LiBH4, MeOH
temp time
yield of 5
dr ratio
(4b:4a)
entry
amination
reduction
picoline·BH3
pyridine·BH3
Me3N·BH3
Et3N·BH3
yieldsb
39%
45%
54%
70%
<5%
51%
<5%
35%
44%
26%
1
2
NDc
24%d (5b-
Boc)
NH4NO3,
AcOH, MeOH
NH4NO3,
AcOH, MeOH
NH4NO3,
AcOH, MeOH
NH4NO3,
AcOH, MeOH
NH4NO3,
AcOH, MeOH
NH4Cl, AcOH,
MeOH
NH4HCO3,
AcOH, MeOH
NH4OAc,
1
2
9:1
4:1
9:1
10:1
-
rt 16h 1:1.5
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
3
4
5
6
7
8
9
K-selectride, THF
BH3·Me2S, THF
BH3·THF, THF
NaCNBH3, AcOH, EtOH
Et3SiH, TFA, DCM
Red-Al, THF
0 oC-rt 16h
60 oC 16h
60 oC 16h
-
-
-
<10%
<10%
<10%
49%d (5a)
<10%
<10%
<10%
<10%
NDc
43%d (5a)
61%d (5a)
58%d (5a)
51%d (5b-
Boc)
36%d (5b-
Cbz)
75%d (5b-
Cbz)
3
rt 60h 3:1
4
rt 16h
rt 16h
rt 16h
-
-
-
-
-
5
tBuNH2·BH3
Et3N·BH3
LiAl(OtBu)3, THF
10 NaBH(OAc)3, AcOH, THF 60 oC 16h
6
9:1
-
11
Me4NBH(OAc)3, THF
rt 16h
12 NaCNBH3, PhCOOH, EtOH rt 60h 2:1
13 NaCNBH3, tBuCOOH, EtOH rt 60h 3:1
14 NaCNBH3, tBuCOOH, EtOH 60 oC 6h 3:1
7
Et3N·BH3
8
Et3N·BH3
6:1
8:1
4:1
AcOH, MeOH
NH4NO3,
AcOH, EtOH
NH4NO3,
AcOH, iPrOH
15
16e
17e
LiBH4, MeOH
LiBH4, MeOH
LiBH4, MeOH
60 oC 0.5h 1:1.5
9
Et3N·BH3
rt 1h 1:5
10
Et3N·BH3
60 oC 0.5h 1:5
aAll reactions were carried out with 0.05 mmol 1-Boc, 0.5
mmol ammonium salts and 0.6 mmol acid at room tempera-
ture for 3h. The resulting mixture was then cooled to -10 oC
and treated with 0.06 mmol reducing agent with stirring and
temperature allowed to equilibrate to room temperature
overnight. The crude product was extracted with EtOAc, the
recovered organics combined and, after removing solvent, the
residue was treated with Boc2O and TEA in methanol at 40 oC.
Upon completion, the dr ratios of crude products were ana-
lyzed by NMR. See SI for details. bIsolated yield of 4b.
aAll reactions were carried out with 0.05 mmol 3a or 3b and
0.2 mmol reducing agent under specific conditions. See SI for
details. Upon completion, the 2’-eq/2’-ax ratios (5a/c:5b/d)
of crude products were analyzed by proton NMR. Not deter-
mined or decomposed product observed. dIsolated yields from
c
e
scale-up reactions (1-4 mmol 3a or 3b). Using Cbz instead of
Boc protection.
Scheme 4. Synthesis of chalcose precursor 5e and
desosamine.
Scheme 3. Synthesis of 3,4,6-trideoxy-3-aminohexoses
precursors.
example D-desosamine, anomeric glycoside hydrolysis of 6a
(Scheme 3) to the free reducing sugar followed by selective re-
ductive amination with excess formaldehyde led to efficient pro-
duction of D-desosamine (2 steps, 75% yield).
observed with the corresponding amino-based comparators 4a and
4b.
To assess platform utility for the synthesis of 3-O-alkyl- or 3-N-
alkyl-deoxysugars, naturally-occurring D-chalcose and D-
desosamine5a were selected as method validation targets (Scheme
4). For the 3-O-methyl-substituted example D-chalcose, 3’--
hydroxyl 3a regioselective methylation was accomplished using
iodomethane and silver oxide to afford the desired precursor 3c
(See 2D NMR on Figure S20-S22). Established 2’-hemiacetal
reduction conditions that favored equatorial product (sodium cya-
noborohydride) led to the desired D-chalcose precursor 5e (58%
yield, 2:1 eq/ax ratio). For the 3-N,N-dimethyl- substituted
To further explore utility, the method was applied toward the
synthesis of the 3,4,6-trideoxysugars (Scheme 5). Specifically,
Barton-McCombie deoxygenation16 of 3a led to efficient conver-
sion to 3e (2 steps, 42% yield). Subsequent 2’-hemiacetal reduc-
tion using conditions demonstrated to favor equatorial product
(sodium cyanoborohydride) gave desired product 7a (87%, dr 9:1)
with similar yields and stereoselectivity as prior examples. In
contrast, using conditions demonstrated to favor axial product
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 4 of 7
Table 5. Final deprotection strategies and summary of
synthetic outcomes.
1
2
3
4
5
6
7
8
9
yields of 9a
()b
yields
of 8a
overall yields
(steps)c
entry
1
substrates
Scheme 5. Synthesis of trideoxy precursors 7a-b.
83% 91% (6/1)
80% 81% (2/1)
91% 81% (1/3)
47% (4)
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Table 4. Summary of 2’-hemiacetal reduction with dif-
ferent substrates.
35% (4)
46% (5)e
2d
3
58% (4)
55% (4)
21% (6)
2’-axial
2’-equatorial
entry
R
PG
Boc 1.5:1
ax:eq yieldsa eq:ax yieldsa
1
2
3
4
5
6
7
8
51%
75%
71%
-
3:1
-
>10:1
2:1
61%
-
-OH
-OH
-OH
-OMe
-NHBoc
-NHBoc
=N-OBn
H
4
5
83% 87% (2/1)
83% 85% (1/1.5)
Cbz
Boc
Boc
Boc
Boc
Boc
Boc
5:1
6:1
-
80%
58%
62%
78%
81%
87%
4:1
3:1
-
72%
65%
-
3:1
>10:1
>10:1
9:1
1:1
44%
32% (6)
28% (7)f
6
7
80% 88% (1.2/1)
93% 94% (1/1)
aIsolated yields.
(lithium borohydride), or a range alternative reduction conditions
(Table 4), lacked stereoselectivity in the conversion to 7b.
40% (6)
47% (5)
Importantly, all late-stage intermediates described in the preced-
ing sections were readily resolved via standard normal phase col-
umn chromatography. Two distinct deprotection strategies were
employed to afford free sugars or their corresponding actinamino-
glycosides (Table 5). For the former, hydrochloric acid under
elevated temperatures gave efficient global deprotection. Alterna-
tively, treatment with TFA afforded the corresponding desired
actinaminoglycosides to facilitate structure elucidation of final
products via 2D-NMR (Figure S2). Within this context, NMR
experiments were conducted at higher temperatures (278K-358K)
to reduce spectral complexity deriving from secondary amide
conformers (Figure S1). As summarized in Table 5, overall yields
of final deoxyhexoses via the divergent synthetic method from
spectinomycin ranged from 12% to 58% over 4-7 (highly con-
served) steps. Compared to previously reported syntheses of 4,6-
dideoxy-glucose (steps/yield: current 4/47%; previously reported
5/20%),5d 4,6-dideoxy-mannose (steps/yield: current 5/46%; pre-
viously reported 7/24%),3b 4,6-dideoxy-allose (steps/yield: current
4/58%; previously reported 11/5%),3a 4,6-dideoxy-3-amino-
glucose (steps/yield: current 6/32%, previously reported 4/29%)6c
and D-chalcose (steps/yield: current 6/21%, previously reported
7/5%),4a the current method provides notable improvement in
efficiency and overall yields. Given the antibacterial activity of
spectinomycin and and semi-synthetic spectinamides,15,17 the anti-
bacterial properties of the corresponding actinaminoglycosides
8a-8j (Table S1) were also assessed. Intriguingly, a number of the
actinaminoglycosides retained moderate to weak anti-Gram-(-)
activity with the most potent analogue (8e which derives from 5e
Table 5) displaying a 5-fold reduction in potency compared to the
parent spectinomycin.
8
9
90% 91% (2/1)
90% 82% (5/1)
35% (5)
10
11
75% 79% (1/2)
77% 80% (1.5/1)
24% (6)
12% (6)
aIsolated yields. bThe ratio of  anomers was indicated in
the parentheses. Calculated from spectinomycin to final de-
oxy-hexoses based on the shortest steps indicated in the pa-
rentheses. dFor the Cbz protected 5b-Cbz, catalytic hydro-
genation was used to remove Cbz and acidic hydrolysis was
then conducted using 2N HCl (See SI for details). When using
Cbz as protective group in the route. fOverall yield for
desosamine.
c
e
3. CONCLUSIONS
In summary, by leveraging the unique cis-cisoid-trans-fused tri-
cyclic framework of spectinomycin, an efficient divergent syn-
thetic strategy to access an array of uniquely functionalized mon-
osaccharides was developed. Sterics and/or potential substrate-
specific catalyst coordination were putative stereoselectivity driv-
ACS Paragon Plus Environment

Page 5 of 7
Journal of the American Chemical Society
plex with the large ribosomal subunit. Proc. Natl. Acad. Sci. 2011, 108,
2717.
ers of the central consecutive 2’- and 3’-reduction reactions for
1
2
3
4
5
6
7
8
this divergent platform. Method validation included the synthesis
of all possible 2,3-stereoisomers of 4,6-dideoxysugars, 3,4,6-
trideoxy-3-aminosugars and both stereoisomers of 3,4,6-
trideoxysugars as well as representative application to a 3-O-
3. a) Keck, G. E.; Boden, E. P.; Wiley, M. R. Total synthesis of (+)-
colletodiol: new methodology for the synthesis of macrolactones. J.
Org. Chem. 1989, 54, 896. b) Nishio, T.; Miyake, Y.; Kubota, K.; Yamai,
M.; Miki, S.; Ito, T.; Oku, T. Synthesis of the 4-, 6-deoxy, and 4,6-
dideoxy derivatives of D-mannose. Carb. Res. 1996, 280, 357. c) Chris-
tina, A.E.; Blas Ferrando, V. M.; de Bordes, F.; Spruit, W. A.; Overkleeft,
H. S.; Codée, J. D. C.; van der Marel, G. A. Multigram-scale synthesis of
an orthogonally protected 2-acetamido-4-amino-2,4,6,-trideoxy-D-
galactose (AAT) building block. Carb. Res. 2012, 356, 282. d) Emmadi,
M. Kulkarni, S. S. Recent advances in synthesis of bacterial rare sugar
building blocks and their applications. Nat. Prod. Rep. 2014, 31, 870. e)
Sanapala, S. R.; Kulkarni, S. S. Expedient route to access rare deoxy
amino L-sugar building blocks for the assembly of bacterial glycocon-
jugates. J. Am. Chem. Soc. 2016, 138, 4938. f) Witczak, Z. J.; Bielski, R.
Recent examples of novel synthetic approaches to diverse amino
sugars. Carbohydr. Chem. 2017, 42, 344. g) Palo-Nieto, C.; Sau, A.;
Galan, M. C. Gold(I)-catalyzed direct stereoselective synthesis of deox-
yglycosides from glycals. J. Am. Chem. Soc. 2017, 139, 14041. h) Qin, C.;
Schumann, B.; Zou, X.; Pereira, C. L.; Tian, G.; Hu, J.; Seeberger, P. H.;
Yin, J. Total synthesis of a densely functionalized Plesiomonas shigel-
loides serotype 51 aminoglycoside trisaccharide antigen. J. Am. Chem.
Soc. 2018, 140, 3120.
alkyl-4,6-dideoxysugar (chalcose) and
a 3-N,N-dialkyl-3,4,6-
trideoxysugar (desosamine). This methodology expands the reper-
toire of uniquely-functionalized sugars available as synthetic
building blocks and/or for sugar conjugation technologies.18,19 In
addition, access to diverse actinamine-based glycosides, such as
those represented in the current study, may present new opportu-
nities as putative reagents for spectinomycin biosynthetic studies20
and/or aminoglycoside-based antibiotic lead/probe discovery.17
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
ASSOCIATED CONTENT
Supporting Information
Supporting Information Available: Experimental procedures,
1
characterization data for all products, and copies of H, 13C, and
2D NMR and HR-ESI-MS spectra. This material is available free
of charge via the Internet at http://pubs.acs.org.
4. a) Schmidt, R. R.; Kufner, U. Divinylglykole zur synthese von desox-
yhexosen ‐ synthese von D‐ und L‐chalcose. Angew. Chem. 1986, 98,
90. b) Danishefsky, S. J.; Bilodeau, M. T. Glycals in organic synthesis:
the evolution of comprehensive strategies for the assembly of oligo-
saccharides and glycoconjugates of biological consequence. Angew.
Chem. Int. Ed. 1996, 35, 1380. c) Kirschning, M.; Jesberger, M.; Schon-
ing, K. U. Concepts for the total synthesis of deoxy sugars. Synthesis
2001, 507. d) Babu, R. S.; Zhou M.; O’Doherty, G. A. De novo synthesis
of oligosaccharides using a palladium-catalyzed glycosylation reac-
tion. J. Am. Chem. Soc. 2004, 126, 3428. e) Northrup, A. B.; MacMillan,
D. W. C. Two-step synthesis of carbohydrates by selective aldol reac-
tions. Science 2004, 305, 1752. f) Enders, D.; Gondal, C. Direct organo-
catalytic de novo synthesis of carbohydrates. Angew. Chem. Int. Ed.
2005, 44, 1210. g) Guo, H.; O’Doherty, G. A. De novo asymmetric syn-
thesis of the anthrax tetrasaccharide by a palladium-catalyzed glyco-
sylation reaction. Angew. Chem. Int. Ed. 2007, 46, 5206. h) Yu, X.;
O’Doherty, G. A. De novo synthesis in carbohydrate chemistry: from
furans to monosaccharides and oligosaccharides. ACS Sym. Series
2008, 990, 3. i) Boltje, T. J.; Buskas, T.; Boons, G.-J. Opportunities and
challenges in synthetic oligosaccharide and glycoconjugate research.
Nat. Chem. 2009, 1, 611. j) Shan, M.; Xing, Y.; O’Doherty, G. A. De novo
asymmetric synthesis of an α-6-deoxyaltropyranoside as well as its 2-
/3-deoxy and 2, 3-dideoxy congeners. J. Org. Chem. 2009, 74, 5961. k)
Pragani, R.; Stallforth, P.; Seeberger, P. H. De novo synthesis of a 2-
acetamido-4-amino-2,4,6-trideoxy-D-galactose (AAT) building block
for the preparation of a Bacteroides fragilis A1 polysaccharide frag-
ment. Org. Lett. 2010, 7, 1624. l) Song, W.; Zhao, Y.; Lynch, J. C.; Kim, H.;
Tang, W. Divergent de novo synthesis of all eight stereoisomers of 2, 3,
6-trideoxyhexopyranosides and their oligomers. Chem. Comm. 2015,
51, 17475.
5. a) Achatz, S.; Domling, A. Desosamine in multicomponent reactions.
Bioorg. Med. Chem. Lett. 2006, 16, 6360. b) Koehn, F. E. Biosynthetic
medicinal chemistry of natural product drugs. MedChemComm. 2012,
3, 854. c) Kirschning, A.; Hahn, F. Merging chemical synthesis and
biosynthesis: A new chapter in the total synthesis of natural products
and natural product libraries. Angew. Chem. Int. Ed. 2012, 51, 4012. d)
Gantt, R. W.; Peltier-Pain, P.; Singh, S.; Zhou, M.; Thorson, J. S. Broaden-
ing the scope of glycosyltransferase-catalyzed sugar nucleotide syn-
thesis. Proc. Natl. Acad. Sci. 2013, 110, 7648.
6. a) Davidson, M. H.; McDonald, F. E. Stereoselective synthesis of D-
desosamine and related glycals via tungsten-catalyzed alkynol cycloi-
somerization Org. Lett. 2004, 6, 1601. b) Velvadapu, V.; Andrade, R. B.
Concise syntheses of D-desosamine, 2-thiopyrimidinyl desosamine
donors, and methyl desosaminide analogues from D-glucose. Carbo-
hydr. Res. 2008, 343, 145. c) Zhang, Z.; Fukuzaki, T.; Myers, A. G. Syn-
thesis of D-desosamine and analogs by rapid assembly of 3-amino
sugars. Angew. Chem. Int. Ed. 2016, 55, 523.
AUTHOR INFORMATION
Corresponding Author
E-mail: jsthorson@uky.edu.
Author Contributions
§These authors contributed equally to this work.
Notes
The authors declare the following competing financial interest:
J.S.T. is a co-founder of Centrose (Madison, WI, USA).
ACKNOWLEDGMENT
This work was supported by National Institutes of Health grants
R37 AI52188 and R01 GM115261 (JST), T32 DA016176 (YZ),
the University of Kentucky College of Pharmacy, the National
Center for Advancing Translational Sciences (UL1TR000117 and
UL1TR001998), and National Natural Science Foundation of
China (No. 21877062, YZ) and the key research projects of Jiang-
su Higher Education (No. 18KJA360010, YZ). We also thank
the College of Pharmacy Analytical Facility for NMR and MS
support.
REFERENCES
1. a) Liu, H. W.; Thorson, J. S. Pathways and mechanisms in the bio-
genesis of novel deoxysugars by bacteria. Ann. Rev. Microbiol. 1994,
48, 223. b) De Lederkremer, R. M. Marino, C. Advances in Carbohydrate
Chemistry and Biochemistry, Vol 61, Academic press: Washington D.C.;
2008; pp 143. c) Elshahawi, S. I.; Shaaban, K. A.; Kharel, M. K.; Thor-
son, J. S. A comprehensive review of glycosylated bacterial natural
products. Chem. Soc. Rev. 2015, 44, 7591.
2. a) Schlunzen, F.; Zarivach, R.; Harms, J.; Bashan, A.; Tocilj, A.; Al-
brecht, R.; Yonath, A.; Franceschi, F. Structural basis for the interac-
tion of antibiotics with the peptidyl transferase centre in eubacteria.
Nature, 2001, 413, 814. b) Borisova, S. A.; Zhang, C.; Takahashi, H.;
Zhang, H.; Wong, A. W.; Thorson, J. S.; Liu, H. W. Substrate specificity of
the macrolide-glycosylating enzyme pair DesVII/DesVIII: Opportuni-
ties, limitations and mechanistic hypotheses. Angew. Chem. Int. Ed.
2006, 45, 2748. c) Zhang, C.; Fu, Q.; Albermann, C.; Li, J.; Thorson, J. S.
The in vitro characterization of the erythronolide mycarosyltransfer-
ase EryBV and its utility in macrolide diversification. ChemBioChem
2007, 8, 385. d) Belousoff, M. J.; Shapira, T.; Bashan, A.; Zimmerman,
E.; Rozenberg, H.; Arakawa, K.; Kinashi, H.; Yonath, A. Crystal structure
of the synergistic antibiotic pair, lankamycin and lankacidin, in com-
7. a) Altmann, K.-H.; Gaugaz, F. Z.; Schiess, R. Diversity through semi-
synthesis: The chemistry and biological activity of semisynthetic
epothilone derivatives. Mol. Divers. 2011, 15, 383. b) Crane, E. A.;
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 6 of 7
Gademann, K. Capturing biological activity in natural product frag-
cules. Nat. Prod. Rep. 2011, 28, 1811. b) Williams, G. J.; Yang, J.; Zhang,
C.; Thorson, J. S. Recombinant E. coli prototype strains for in vi-
vo glycorandomization. ACS Chem. Biol. 2011, 6, 95. c) Peltier-Pain, P.;
Marchillo, K.; Andes, D. R.; Thorson, J. S. Natural product disaccharide
engineering through tandem glycosyltransferase catalysis reversibil-
ity and neoglycosylation. Org. Lett. 2012, 14, 5086. d) Zhang, J.; Singh,
S.; Hughes, R. R.; Zhou, M.; Sunkara, M.; Morris, A. J.; Thorson, J. S. A
simple strategy for glycosyltransferase-catalyzed aminosugar nucleo-
tide synthesis. ChemBioChem 2014, 15, 647. e) Zhang, J.; Hughes, R. R.;
Saunders, M. A.; Elshahawi, S. I.; Ponomareva, L. V.; Zhang, Y.; Win-
chester, S. R.; Scott, S. A.; Sunkara, M.; Morris, A. J.; Prendergast, M. A.;
Shaaban, K. A.; Thorson, J. S. Identification of neuroprotective spox-
azomicin and oxachelin glycosides via chemoenzymatic glycosyl-
scanning. J. Nat. Prod. 2017, 80, 12. f) Hughes, R. R.; Shaaban, K. A.;
Zhang, J.; Cao, H.; Phillips, G. N. Jr.; Thorson, J. S. OleD Loki as a catalyst
for tertiary amine and hydroxamate glycosylation. ChemBioChem
2017, 18, 363. g) Hughes, R. R.; Shaaban, K. A.; Ponomareva, L. V.;
Horn, J.; Zhang, C.; Zhan, C.-G.; Voss, S. R.; Leggas, M.; Thorson, J. S.
Oled Loki as a catalyst for hydroxamate glycosylation. ChemBioChem
2020, 21, 952.
19. a) Goff, R. G.; Thorson, J. S. Neoglycosylation and neoglycorandom-
ization: Enabling tools for the discovery of novel glycosylated bioac-
tive probes and early stage leads. MedChemComm 2014, 5, 1036. b)
Lyer, A. K. V.; Zhou, M.; Azad, N.; Elbaz, H.; Wang, L.; Rogalsky, D. K.;
Rojanasakul, Y.; O’Doherty, G. A.; Langenhan, J. M. A direct comparison
of the anticancer activities of digitoxin MeON-neoglycosides and O-
glycosides. ACS Med. Chem. Lett., 2010, 1, 326. c) Nandurkar, N. S.;
Zhang, J.; Ye, Q.; Ponomareva, L. V.; She, Q. B.; Thorson, J. S. The identi-
fication of perillyl alcohol glycosides with improved antiproliferative
activity. J. Med. Chem., 2014, 57, 7478. d) Zhang, J.; Ponomareva, L. V.;
Nandurkar, N. S.; Yuan, Y.; Fang, L.; Zhan, C. G.; Thorson, J. S. Influence
of sugar amine regiochemistry on digitoxigenin neoglycoside anti-
cancer activity. ACS Med. Chem. Lett. 2015, 6, 1053. e) Cannone, Z.;
Shaqra, A. M.; Lorenc, C.; Henowitz, L.; Keshipeddy, S.; Robinson, V.;
Zweifach, A.; Wright, D.; Peczuh, M. W. Post-glycosylation diversifica-
tion (PGD): an approach for assembling collections of glycosylated
small molecules. ACS Comb. Sci. 2019, 21, 192.
ments by chemical synthesis. Angew. Chem. Int. Ed. 2016, 55, 3882. c)
Wang, S.; Dong, G.; Sheng, C. Structural simplification of natural prod-
ucts. Chem. Rev. 2019, 119, 4180.
8. a) Hanessian, S. Deoxy Sugars, Chap. 9; ACS Advance in Chemistry
Series; 1968, pp 159-201. b) Hanessian, S. Preparative Carbohydrate
Chemistry, Chap. 3; Marcel Dekker: New York; 1997, pp 263-464. c)
Boons, G.-J. Carbohydrate Chemistry, Blackie Academic & Professional:
Glasgow, UK; 1998, pp 1-508. d) Boons, G.-J.; Hale, K. J. Organic Syn-
thesis with Carbohydrates, Chap. 4; Sheffield Academic Press: Sheffield,
UK; 2002, pp 103-154.
9. Farrar, M. A.; Olson, S. H.; Perlmutter, R. M.; Slossber, L. H. WO
2001087309 A1; Nov 22, 2001.
10. Knight, J. C.; Hoeksema, H. Reduction products of spectinomycin. J.
Antibiot. 1975, 28, 136.
11. As Cbz-protection was only used for 1, 3a and 5b, protecting
group(s) were reflected using simple 1-Boc/1-Cbz, 3a-Boc/3a-Cbz
and/or 5b-Boc/5b-Cbz notation where applicable.
12. Kofron, W. G.; Baclawski, L. M. A convenient method for estimation
of alkyllithium concentrations. J. Org. Chem. 1976, 41, 1879.
13. Rosenbrook, W. Jr.; Carney, R. E. Spectinomycin modification I. J.
Antibiot. 1975, 28, 953.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
14. Maier, R.; Woitun, E.; Reuter, A.; Reuter, W.; Wetzel, B. Modifica-
tion of spectinomycin. J. Antibiot. 1981, 34, 16.
15. Liu, J.; Bruhn, D. F.; Lee, R. B.; Zheng, Z.; Janusic, T.; Scherbakov, D.;
Scherman, M. S.; Boshoff, H. I.; Das, S.; Rakesh; Waidyarachchi, S. L.;
Brewer, T. A.; Gracia, B.; Yang, L.; Bollinger, J.; Robertson, G. T.;
Meibohm, B. Lenaerts, A. J.; Ainsa, J.; Böttger, E. C.; Lee, R. E. Structure–
activity relationships of spectinamide antituberculosis agents: A dis-
section of ribosomal inhibition and native efflux avoidance contribu-
tion. ACS Infect. Dis. 2017, 3, 72.
16. Barton, D. H. R.; Crich, D.; Motherwell, W. B. New and improved
methods for the radical decarboxylation of acids. J. Chem. Soc. Chem.
Comm. 1983, 939.
17. a) Lee, R. E.; Hurdle, J. G.; Liu, J.; Bruhn, D. F.; Matt, T.; Scherman, M.
S.; Vaddady, P. K.; Zheng, Z.; Akbergenov, R.; Das, S.; Madhura, D. B.;
Rathi, C.; Trivedi, A.; Villellas, C.; Lee, R. B.; Rakesh; Waidyarachchi, S.
L.; Sun, D.; McNeil, M. R.; Ainsa, J. A.; Boshoff, H. I.; Gonzalez-Juarrero,
M.; Meibohm, B.; Böttger, E. C.; Lenaerts, A. J. Spectinamides: A new
class of semisynthetic antituberculosis agents that overcome native
drug efflux. Nat. Med. 2014, 20, 152. b) Bruhn, D. F.; Scherman, M. S.;
Liu, J.; Scherbakov, D.; Meibohm, B.; Böttger, E. C.; Lenaerts, A. J.; Lee, R.
E. In vitro and in vivo Evaluation of Synergism between anti-
tubercular spectinamides and non-classical tuberculosis antibiotics.
Sci. Rep. 2015, 5, 13985.
20. a) Kim, K. R.; Kim, T. J.; Suh, J. W. The gene cluster for spectinomy-
cin biosynthesis and the aminoglycoside-resistance function
of spcM in Streptomyces spectabilis. Curr. Microbiol. 2008, 57, 371. b)
Zhang, G.; Leclercq, S. O.; Tian, J.; Wang, C.; Yahara, K.; Ai, G.; Liu, S.;
Feng, J. A new subclass of intrinsic aminoglycoside nucleotidyltrans-
ferases,
ANT(3")-II,
is
horizontally
transferred
among Acinetobacter spp. by homologous recombination. PLOS Genet.
2017, 13, e1006602.
18. a) Gantt, R. W.; Peltier-Pain, P.; Thorson, J. S. Enzymatic methods
for glyco(diversification/randomization) of drugs and small mole-
ACS Paragon Plus Environment

Page 7 of 7
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
7
ACS Paragon Plus Environment