Characterization of Highly Coordinated Allylgermanes: Pivotal Players for Enhanced Nucleophilicity and Stereoselectivity

Article abstract of DOI:10.1002/asia.202000392

Allylgermanes with a 4-, 5-, and 6-coordinated germanium center were characterized by X-ray crystallography. Cationic 6-coordinated group 14 allylmetals, which were hitherto assumed to be a transition-state structure of allylations, were successfully isol

Full text of DOI:10.1002/asia.202000392

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Accepted Article
Title: Characterization of Highly Coordinated Allylgermanes: Pivotal
Players for Enhanced Nucleophilicity and Stereoselectivity
Authors: Yohei Minami, Kento Nishida, Akihito Konishi, and Makoto
Yasuda
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Chemistry - An Asian Journal
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COMMUNICATION
Characterization of Highly Coordinated Allylgermanes: Pivotal
Players for Enhanced Nucleophilicity and Stereoselectivity
[
a]
[a]
[a, b]
and Makoto Yasuda* [a]
Yohei Minami, Kento Nishida, Akihito Konishi,*
Abstract: The allylgermanes with a 4-, 5-, and 6-coordinated
germanium center were characterized by X-ray crystallography.
Cationic 6-coordinated group 14 allylmetals, which were hitherto
assumed to be a transition-state structure of allylations, were
successfully isolated. Forming high coordination states significantly
enhanced the reactivity of the allylgermanes. In contrast to the 4-
coordinated allylgermanes with low reactivity, the highly coordinated
species readily reacted with several aldehydes. Furthermore, the high
coordination states exerted a significant effect on the E/Z selectivity
of allylation depending on external additives. The coordination
structure had a dramatic influence on the electronic and steric
environments around the Ge center, enabling the geometrically
controlled allylation of aldehydes.
enantioselective allylations using chiral Lewis bases.[13] Several
types of chiral ligands have been developed for stereoselective
allylations by Malkov[14], Kotora[15], and Nakajima.[16] Through
these pioneering studies, the highly coordinated allylmetals
bearing neutral and/or charged states[17] have been suggested as
the crucial reactive species that characterize the enantio- and
stereoselectivity toward the allylations. Some structural
investigations of the group 14 allylmetals were performed via
NMR and X-ray crystallographic analyses.[18]
A stable 5-
coordinated allylsilane reported by Kawashima exhibited different
reactivity attributing to the intramolecular coordination style.[19]
Despite the coordination mode being the main factor that
determines the reaction profile of the allylation, the experimental
characterizations of the highly coordinated group 14 allylmetals
remains a challenging subject due to their high reactivity. We are
interested in the difference in the reactivity and stereoselectivity
among a series of allylmetals with a 4-, 5-, and 6-coordinated
metal center.
Our recent studies on the germyl enolates[20] demonstrated
that the highly coordinated species with a Ge center were stable
enough to be isolated.[21] These investigations on the highly
coordinated germyl enolates provide us with the hope that
allylgermanes could serve as the molecules of interest in the
characterization of highly coordinated allylmetals. Herein, we
report the structural determination of allylgermanes bearing 4-, 5-,
and 6-coordinated states (Figure 1). The differences in the
coordination styles were plainly reflected in the nucleophilicity of
the allylgermanes and the stereoselectivity of the allylations.
Allylic organometallic reagents are indispensable
[
1]
nucleophiles for carbon–carbon bond-forming reactions. Many
types of allylmetals, which include different metal centers, such
as Mg , Zn , B , In , Si , or Sn[5b][7], have been utilized for the
allylations of carbonyls or imines. The metal center of the
allylmetal is the paramount factor that determines the transition-
state structure. Control of the transition-state structure, either
acyclic- or cyclic, has attracted considerable attention because
the difference in the structure deeply reflects stereoselective bond
formations. The group 14 allylmetals, allylsilanes or stannanes,
have served as interesting subjects for this study. They possibly
assume both of the acyclic and cyclic transition states depending
[
2]
[3]
[4]
[5]
[6]
on the reaction conditions[ and substituents on the metal or
8]
[9]
additive ligands.[10]
The coordination of the ligands into the metal center dictates
the reactivity of the allylsilanes and governs the nucleophilicity of
the allylic moiety and/or the Lewis acidity of the metal center.[
Kobayashi and coworkers developed the allylation of aldehydes
with allyltrichlorosilanes in the presence of a catalytic amount of
DMF.[12] The coordination of DMF into the Si center, as well as the
This work: Structural determination of a series of allylgermanes
11]
X
L
L
X
X
L
L
X
Ge
Ge
Ge
X
X
X
X
X
enough Lewis acidity on the Si center induced by Cl atoms,
enhanced the nucleophilicity of the allyl moiety and promoted
allylation. Denmark and coworkers reported the catalytic
4-coordinated
neutral
5-coordinated
neutral
6-coordinated
cationic
Figure 1. Current study: structural determination of allylgermanes and
observation of reactive species
[
a]
Dr. Y. Minami, K. Nishida, Dr. A. Konishi, Prof. Dr. M. Yasuda
Department of Applied Chemistry
Graduate School of Engineering
Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)
E-mail: yasuda@chem.eng.osaka-u.ac.jp
a-koni@chem.eng.osaka-u.ac.jp
We initially examined the reductive generation of
allylgermanes from divalent germanium salts and allyl halides,
which was monitored by H NMR measurement. Saigo’s group
1
[
b]
Dr. A. Konishi
Center for Atomic and Molecular Technologies,
Graduate School of Engineering,
Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)
E-mail: a-koni@chem.eng.osaka-u.ac.jp
has reported the Barbier-type allylation of aldehyde using GeI
as
in
2
[22]
a reductant in DMF. The reaction of GeI
2
with iodopropene
1
CH
A).[22] The H NMR spectrum of
allyl structure (Scheme 1B). The solid-state structure was
3
CN quantitatively afforded allyltriiodogermane
2
(Scheme
1
clearly showed a typical 1
1
2
-
Supporting information for this article is given via a link at the end of
the document.
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Chemistry - An Asian Journal
10.1002/asia.202000392
COMMUNICATION
determined in the diaryl derivative
4
(Scheme 1C). The X-ray
revealed the 4-coordinated
germanium center (Figure 2A). The geometry around the
germanium center of assumes a tetrahedral structure; the sum
of the three angles of the I‒Ge‒I (325.8˚) supports a sp3
hybridization for the Ge atom. The dihedral angle of 111.5˚ in the
alter the formally cationic Ge center, which suggests that the
external additives are not suitable ligands for the isolation of
highly coordinated allylgermanes.
crystallographic analysis of
4
4
We therefore designed the allyl halide
intramolecular coordination group. For the coordination group, an
-dimethyl carbamoyl group was selected because the
6 with an
-
N,N
[
23]
Ge–C

–C

–C

moiety implies the potential hyperconjugation of
–C ). The bond length of the C –C 1.333(4) Å)
carbonyl can coordinate to the metal center of allylmetals. The
reduction of allyl bromide with GeBr -dioxane furnished the
neutral 5-coordinated allyltribromogermane (Figure S5). The
subsequent replacement of bromides on the Ge center with
iodides was conducted by the treatment of with NaI, to afford
the neutral 5-coordinated allyltriiodogermane X-ray
crystallographic analysis of illustrated that the Ge center of

(Ge–C

)–
(C




6
2
lies within the range of the typical C‒C double bond.
7
7
8
.
8
8
has a trigonal bipyramidal geometry (Figure 3A). The coordinating
oxygen atom was placed at an axial position and the allyl
substituent was placed at an equatorial position. The change in
the coordination structure expanded the Ge–C
lengths of (2.007(4)/1.348(4) ) relative to those of
1.965(3)/1.333(4) ), suggesting the enhancement of
nucleophilicity of the allylic moiety of . The IR measurement of
in CH Cl showed a lower energy-shifted stretching vibration of
the C=O group than that of the precursor , suggesting the
  
/C –C bond
8
Å
4
(
Å
8
8
2
2
6
preservation of the 5-coordinated structure even in the solution
state (Table S1). The characterizations of the cationic highly
coordinated allygermanes were realized (Scheme 2B). The
treatment of the allyl chloride
-coordinated allyltrichlorogermane 10 (Figure S7)
the exchange of a chloride of 10 with a perchlorate by AgClO
9
with GeCl
2
-dioxane furnished the
4
.
Subsequently,
4
,
followed by the addition of 1,10-phenanthroline afforded the
cationic 6-coordinated allylgermane 11 (Scheme 2B, Figure 3B).
Notably, cationic 6-coordinated allylmetals have been proposed
as possible structures in the transition state of allylsilanes by
Denmark,[13b,d] Malkov,[14f] and Wheeler.[17a,b] Our structural
determination of 11 is the first experimental evidence that
characterizes the cationic and highly coordinated state in the
group 14 allylmetals.
Scheme 1. Synthesis of 4-coordinated allylgermanes 2 and 4. (A) Reductive
generation of allyltriiodogermane 2 from iodopropene 1 and GeI
2
; (B) NMR
obsevation of generation of 2 in CD
crystalline allylgermane 4 and 5.
3
CN solution (400 MHz); (C) Generation of
Figure 2. Molecular structure of 4-coordinated allylgermanes (A) 4 and (B) 5.
Ellipsoids are shown at the 50% probability level. Hydrogen atoms, except allyl
moieties, and solvent molecules are omitted for clarity.
Scheme 2. (A) Synthesis of 5-coordinated allylgermanes 7 and 8 from allyl
bromide derivative 6; (B) Synthesis of cationic 6-coordinated allylgermane 11.
Next, the structural determinations of the highly coordinated
allyl germanium species were attempted by adding ligands into
the 4-coordinated allylgermane
such as pyridine, HMPA, PPh
unfortunately, no coordination into the Ge center of
4
. Several ligands were used,
, DMAP, and TMEDA, but
was
3
4
observed presumably due to the low Lewis acidity of the Ge
center. 1,3-Bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) did
coordinate into the Ge center to give a cationic 4-coordinated
allylgermane
5 (Figure 2B). The high basicity of the N-heterocyclic
carbene (NHC) ligand and the high leaving ability of iodide should
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Chemistry - An Asian Journal
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COMMUNICATION
Figure 3. Molecular structures of highly coordinated allylgermanes (A) 8 and
(A) Synthesis of 5-coordinated allylgermane 14
(
B) 11. Ellipsoids are shown at the 50% probability level. Hydrogen atoms,
Br Br
-dioxane Br Ge
I I
O
1
eq. GeBr
2
O
3.5 eq. NaI
I
Ge
O
except allyl moieties, and solvent molecules are omitted for clarity.
Br
N
MeCN
MeCN
RT, 3 h
quant.


N
N
-
10 °C, 78 h

12
13
X-ray
14
4
8%
The effect of the highly coordinated structures on the
allylation of aldehydes was investigated. Unfortunately, the
Allylation of 15 with allylgermanes
(
B) 4-coordinated allylgermane 2
I
4, 8, and 11 did not react with any
O
OH
isolated diaryl derivatives

Ge


+
I
Ar
H
carbonyls due to steric hindrance on the-position. We prepared
the pristine allylgermanes without the terminal aryl groups
MeCN
RT, 24 h
Ar
I
Ar = 4-ClC
6
H
4
2
15
16 (0%)

C

C

= 11.6 ppm
(
Scheme 3A). The allyl bromide 12 was applied for the synthesis
of the neutral 5-coordinated allylgermane. For the treatment of 12
with GeBr -dioxane, the Ge(IV) center was regioselectively
(
C) 5-coordinated allylgermane 14
I
I
OH
O
E
2
I
Ge
O
N
+
Ar
introduced in the inside carbon of 12, in which the carbonyl
intramolecularly coordinates to the Ge center, resulting in the
neutral 5-coordinated allyltribromogermane 13 (Figure S9). The
subsequent replacement of bromides on the Ge center with
iodides afforded the 5-coordinated allyltriiodogermane derivative

Ar
H
MeCN
RT, 24 h

N
O

Ar = 4-ClC
6
H
4
1
4
15
17 (72%)

C
C
  = 17.3 ppm
E/Z = 98:2
(
D) Addition of 1,10-phenanthroline
I
I
OH
Ar
O
Ge
O
1
,10-phenanthroline
Z
I
+
1
4, which was characterized by NMR and IR measurements. The
Ar
H
MeCN
N
N
1
H NMR measurement showed that 14 assumes the 1-allyl
Ar = 4-ClC
6
H
4
RT, 24 h
14
15
17 (72%)
O
structure.
E/Z = 25:75
The highly coordinated allylgermane 14 exerted significant
impacts on the reactivity and stereoselectivity which occurred in
the allylations. We performed
chlorobenzaldehyde 15 in CH CN. The allylation of 15 with the 4-
coordinated allyltriiodogermane in CH CN resulted in no
reaction (Scheme 3B). Considering Saigo’s result conducted in
DMF, the coordination of DMF molecules to the Ge center should
activate the allyl moiety to promote the allylation in DMF. A similar
solvent effect is observed for the allyltrichlorosilane reported by
Kobayashi.[12] On the other hand, the allylation of 15 with the 5-
a
model allylation of 4-
Scheme 3. (A) Synthesis of pristine 5-coordinated allylgermane 14; (B)
Allylation of 15 with 4-coordinated allylgemane 2; (C) E-selective allylation of 15
with 5-coordinated allylgermane 14; (D) Z-selective allylation of 15 with 5-
coordinated allylgermane 14 in the presence of 1,10-phenanthroline.
3
2
3
[
22]
To further understand the differences in electronic
properties between 4- and 5-coordinated allygermanes, we
performed molecular orbital (MO) and NBO analyses by using
DFT calculations (Figure 4). Forming highly coordinated states
3
coordinated allyltriiodogermane 14 proceeded even in CH CN to
give the corresponding alcohol 17 in 72% yield (Scheme 3C). This
result implies that the highly coordinated state improves the
reactivity of allylgermane even in the non-coordinating solvent.
significantly impacts the MO energy level of the allylic
 bonding
orbital and the atomic charge on the Ge center. Upon the increase
in the coordination number from four to five, the energy level of
13
The enhanced reactivity of 14 was clearly confirmed by C NMR
the allylic
eV; Figure 4A), which agrees with the higher nucleophilicity of 14
The second order perturbation analysis on the NBO calculation
indicated that the hyperconjugation from the (Ge– C ) bond to
the *(C =C ) bond was much more effective in 14 E = 6.89
kcal/mol) than E = 6.06 kcal/mol) (Table S5, Figure S10),
 bonding orbital is destabilized (2: –7.38 eV; 14: –7.05
measurements (Figure S1). The difference in the chemical shifts
.
between the allylic carbons (C
estimate the polarization of the allyl double bond. The larger
difference in  corresponds to the more polar allyl double
bond. The value of 14 (17.3 ppm) was larger than that of
11.6 ppm), which strongly illustrated that the highly coordinated
allylgermane 14 has a stronger nucleophilicity than the 4-
coordinated allylgermane . The halogens on the Ge center
somewhat influenced the reactivity; the allyltribromogermane
 
and C ) is a suitable index to


C –C
 




(
2
2
(
(
illustrating that the electronic communication between the allylic
moiety and the Ge center is pronounced in highly coordinated
allylgermanes. In addition, the more positive Ge center was
generated in the 5-coordinated 14 (+0.808) rather than in the 4-
2
3
derivative 13 also reacted with 15 in CH CN in lower yield (33%,
Table S2 and S3).
coordinated
2 (+0.769) (Figure 4B). The more cationic Ge center
in 14 should work as the Lewis acidic center in the allylations of
aldehydes, which facilitates the reaction proceeding. The
halogens on the Ge center are also important. Replacement of
iodides on the Ge center of 14 with bromides or chlorides
stabilizes the allylic
interactions between the

bonding orbital (Table S5) and weakens the
(Ge–C and *(C =C bonds,


)



)
supporting the experimental results that the allyltriiodidegermane
derivatives exhibited the higher reactivity.
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Chemistry - An Asian Journal
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COMMUNICATION
allylgermanes. The moderate Lewis acidity of the Ge center in the
highly coordinated states, which is in sharp contrast to the Si or
Sn[20c] center, realizes the switchable stereoselectivity.
[
28]
Figure 4. (A) Selected molecular orbitals associated with allylic  bonding
orbitasl for 2 and 14, and (B) NBO atomic charges for the Ge center and the
allylic moiety. The calculations were performed at the B3PW91/DGDZVP (for
Ge and I), 6-31+G**(for C, H, O, and N) level.
Scheme 4. Switchable stereoselectivity on allylations of aldehyde 15 with 5-
and 6-coordinated allylgermanes and plausible transition structures TS-1 and
TS-2.
Notably, a high stereoselectivity emerged in the allylation of
15 with 14; an E-isomer 17 was primarily generated (E/Z = 98:2,
Optimizations of the reaction conditions for both of the
E-
Scheme 3C). The stereoselectivity in the allylation significantly
and
Z-selective allylation were explored, and are summarized in
depended on solvents (Table S3). The allylation of 15 with 13 in
Tables S3 and S4. The allylations of several aldehydes were
investigated (Scheme 5).[29] In the absence of 1,10-
phenanthroline (condition A), the E-selective allylations of various
aldehydes with the in situ generated 14 were demonstrated. The
aromatic aldehydes bearing diverse electronic properties were
tolerated toward the allylation, leading to the corresponding
toluene and CH
= 99:1; CH
Interestingly, the stereoselectivity of the allylation gradually
3
CN afforded 17 with high
E-selectivity (toluene:
E
/Z
3
CN: = 89:11; Table S3, entries 1 and 3).
E/Z
shifted from
In DMF, the
E
E
- to
Z
-selectivity with the increase in solvent polarity.
=53:43, entry
/Z-selectivity were roughly equal (E/Z
4
Z
). Eventually, the allylation of 15 with 13 in HMPA gave 17 with
-selectivity ( = 26:74, entry 7). These results illustrate that the
homoallyl alcohols 17–20 in moderate to good yield with high E-
selectivity. Although electron withdrawing groups on the aromatic
rings slightly decreased the yield, the stereoselectivities were not
E/Z
coordination of ligands to a Ge center can overturn the
stereoselectivity of the allylation. Thus, we investigated the
allylation in the presence of several bidentate ligands (Table S4).
When adding 1,10-phenanthroline as a bidentate ligand, the
allylation of 14 with 15 afforded 17 with
(E/Z
coordination of additives dramatically changed the structure of the
transition state in the allylation of highly coordinated
allylgermanes (Scheme 4). A six-membered ring transition state
is proposed in the allylations of benzaldehyde with
allylgermanes.[22] For the 5-coordinated 14 in the absence of
affected (17
give the product in high yield (19). The reaction conditions were
also applied to the -unsaturated aldehyde but the allylation
was followed by dehydration to give a corresponding conjugated
)-triene derivative (20'). The -selective allylations of these
aldehydes with 13 and 1,10-phenanthroline were performed
condition B). For the higher -selectivity, the relatively less
,18). An electron rich aldehyde efficiently reacted to
,
Z-selectivity in 72% yield
= 25:75, Scheme 3D). The results demonstrate that the extra
(E
,E
,E
Z
(
Z
reactive allyltribromogermanes 13 were more appropriate than
allyltriiodogermanes 14. All allylations in the presence of 1,10-
phenanthroline afforded the corresponding homoallyl alcohols
additives, the
the six-membered ring in the transition state, TS-1, to dominantly
give an -isomer (Path A in Scheme 4). In TS-1, the preservation
-substituent is placed at the equatorial position of
1
7
–
20 with high
Z-selectivity. Tuning the highly coordinated
structure by adding the external ligands enabled the sharply
switched E/Z selectivity of the allylation of aldehydes.
E
of the intramolecular coordination should stabilize a cationic Ge
Br Br
O
OH
center, accompanying the elimination of an iodide ion.[
15c]
In
Br Ge
O
condition A or B
N
+
R
H
R
contrast, the bidendate coordination of 1,10-phenanthroline to the
Ge center of 14 would release the intramolecular coordination of
the carbonyl group. The increased steric demand around the Ge
center permits a different conformation of the six-membered ring
N
O
1720
13
condition A
17 X = Cl 59% (E/Z= 96:4) 63% (E/Z= 5:95)
8 X = NO2 24% (E/Z= 91:9) 38% (E/Z= 6:94)
condition B
OH
N
1
transition state TS-2, in which the
axial direction, to preferentially give a
). Notably, the allylations of aldehydes by the
allylsilanes and stannanes generally proceeds with
-selective allylations are only found in the

-substituent is oriented to the
-isomer (Path B in Scheme
-substituted
O
19 X = Me 95% (E/Z= 99:1) 77% (E/Z= 7:93)
X
Z
OH
4

N
E
-
Ph
Ph
selectivity.[24] The
O
N
Z
[
25]
allylations with the allylborons bearing bulky substituents and
the intramolecularly coordinated cyclic allylstannanes.[26]
20'
condition A: 32% (n.d.)[
20
O
a]
condition B: 59% (E/Z= 5:95)
Although Aggawal overturned the
of aldehydes by adding BuLi to allylboronic esters, the control
of selectivity with external ligands via highly coordinated
states is quite rare. The coordination ability of germanium
sufficiently facilitates the formation of highly coordinated
E/Z selectivity of the allylation
condition A: (i) allylgermane 13 (0.45 mmol), NaI (1.5 mmol), MeCN (1.2 mL),
RT, 2 h (ii) aldehydes (0.3 mmol), RT, 48 h. condition B: allylgermane 13 (0.45
mmol), aldehydes (0.3 mmol), 1,10-phenanthroline (0.9 mmol), MeCN (1.2 mL),
RT, 72 h. Isolated yields of the major stereoisomer are shown. The ratios of E/Z
mixtures were determined by 1H NMR measurement of the crude reaction
[
27]
n
E/Z
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Chemistry - An Asian Journal
10.1002/asia.202000392
COMMUNICATION
mixture. The ratios of E/Z mixtures are in parentheses. [a] The product was
obtained as a triene derivative. The ratio of E/Z mixture was not detected.
[2]
N. D. Bartolo, J. A. Read, E. M. Valentín, K. A. Woerpel, Synthesis 2017,
49, 3237–3246.
[
3]
a) I. Marek, G. Sklute, Chem. Commun. 2007, 1683–1691; b) T. Mejuch,
N. Gilboa, E. Gayon, H. Wang, K. N. Houk, I. Marek, Acc. Chem. Res.
Scheme 5. Reaction of the 5-coordinated allylgermane 13 with various
aldehydes
2013, 46, 1659–1669.
[
4]
5]
P. V. Ramachandran, P. D. Gagare, D. R. Nicponski, in Compr. Org.
Synth. II, Elsevier, 2014, pp. 1–71.
[
a) Z.-L. Shen, S.-Y. Wang, Y.-K. Chok, Y.-H. Xu, T.-P. Loh, Chem. Rev.
We investigated the transformation of the
products into other functionalized compounds. Oxidation of the
homoallyl alcohols ( )-19 gave corresponding ketones ( )-21
These ketones ( )-21 were smoothly epoxidized into
epoxiamides trans
E/Z isomeric
2
013, 113, 271–401; b) U. K. Roy, S. Roy, Chem. Rev. 2010, 110, 2472–
2
535; c) M. Yasuda, M. Haga, A. Baba, Organometallics, 2009, 28,
E
/
Z
E
/Z
.
1998–2000; d) M. Yasuda, M. Haga, A. Baba, Eur. J. Org. Chem. 2009,
5513–5517; e) M. Yasuda, M. Haga, Y. Nagaoka, A. Baba, Eur. J. Org.
Chem. 2010, 5359–5363.
E
-
/Z
,-
22 and cis
O
-
22 by m-CPBA, respectively.
5
eq. PDC
MS 4 Å
O
[6]
a) P. V. Ramachandran, D. R. Nicponski, P. D. Gagare, in Compr. Org.
Synth. II, Elsevier, 2014, pp. 72–147; b) L. Chabaud, P. James, Y.
Landais, Eur. J. Org. Chem. 2004, 3173–3199.
O
N
2 eq. m-CPBA
CH Cl , RT
(E)-19
p-tol
p-tol
CH
2
Cl
2
, RT
2
2
O
N
[
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Acknowledgements
This work was supported by the JSPS KAKENHI (Grant Numbers
JP15H05848 in Middle Molecular Strategy, JP18H01977,
JP18K19079, and JP18K14201). M.Y. acknowledges support
from the JSPS Fellowship for Young Scientists (19J10386). A.K.
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Chemistry - An Asian Journal
10.1002/asia.202000392
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Entry for the Table of Contents (Please choose one layout)
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Structural determination of a series
of allylgermanes bearing a 4-, 5-,
and 6-coordinated metal center and
evaluation of their nucleophilicity has
been accomplished. The highly
coordinated state enhanced the
reactivity of the allyl moiety. The
Yohei Minami, Kento Nishida, Akihito
Konishi*, and Makoto Yasuda*
Page No. – Page No.
Characterization of Highly
Coordinated Allylgermanes: Pivotal
Players for Enhanced
Nucleophilicity and
Stereoselectivity
E,Z-selectivity toward allylation of
aldehydes dramatically changed
depending on their coordination
structure.
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Author(s), Corresponding Author(s)*
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Title
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