Hydroxynitrile lyase catalyzed enantioselective HCN addition to O-protected α-hydroxyaldehydes

Article abstract of DOI:10.1016/S0957-4166(99)00275-X

Various O-protected glycol- and racemic lactaldehydes 3 and 6 as well as O-allyl protected racemic α-hydroxyaldehydes 7 (R¹=Et, Pr, Bu) have been prepared to investigate and perform a stereoselective Kiliani-Fischer synthesis by hydroxynitrile lyase (HNL) catalyzed addition of HCN. From all protecting groups investigated the allyl moiety was most suitable. (R)-PaHNL from bitter almonds (Prunus amygdalus), yielding the (2S)-cyanohydrins 8-10, was found to be a more stereoselective catalyst than (S)-MeHNL from maniok (Manihot esculenta). While (R)-PaHNL led to enantiomeric excesses ≥93%, with (S)-MeHNL the (2R)-cyanohydrins 8-10 were obtained with enantiomeric excesses ≤78%.

Full text of DOI:10.1016/S0957-4166(99)00275-X

Pergamon
Tetrahedron: Asymmetry 10 (1999) 2817–2828
Hydroxynitrile lyase catalyzed enantioselective HCN addition to
O-protected α-hydroxyaldehydes1
Jürgen Roos † and Franz Effenberger ∗
Institut für Organische Chemie der Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
Received 28 June 1999; accepted 2 July 1999
Abstract
Various O-protected glycol- and racemic lactaldehydes 3 and 6 as well as O-allyl protected racemic
α-hydroxyaldehydes 7 (R1=Et, Pr, Bu) have been prepared to investigate and perform a stereoselective
Kiliani–Fischer synthesis by hydroxynitrile lyase (HNL) catalyzed addition of HCN. From all protecting groups
investigated the allyl moiety was most suitable. (R)-PaHNL from bitter almonds (Prunus amygdalus), yielding the
(2S)-cyanohydrins 8–10, was found to be a more stereoselective catalyst than (S)-MeHNL from maniok (Manihot
esculenta). While (R)-PaHNL led to enantiomeric excesses ≥93%, with (S)-MeHNL the (2R)-cyanohydrins 8–10
were obtained with enantiomeric excesses ≤78%. © 1999 Elsevier Science Ltd. All rights reserved.
2,3-Dihydroxynitriles, readily accessible by addition of HCN to α-hydroxyaldehydes, are useful
synthetic intermediates for the preparation of numerous biologically active compounds. The nitrile group
can be converted by hydrogenating agents to the corresponding aldehyde which once again can be
reacted with HCN to afford 2,3,4-trihydroxynitrile. This systematic chain elongation of carbohydrates
has been known for more than 100 years as the Kiliani–Fischer synthesis,2 and is often used for the
preparation of polyhydroxy compounds. 1,2,3-Amino diols, also available from 2,3-dihydroxynitriles by
direct hydrogenation or by Grignard addition and subsequent hydrogenation,3 are found as components
in a number of important pharmaceuticals such as β-blockers,4 renin inhibitors5 as well as 3-amino-
2,3,6-trideoxyhexoses in anthracycline antibiotics.6
Nearly all biologically active and pharmacologically relevant polyhydroxy and aminohydroxy com-
pounds have one or more stereogenic centres, and thus stereoselective syntheses of these compounds are
of particular interest. By addition of HCN to aldehydes to give cyanohydrins a new stereogenic centre is
generated. Thereby, as expected for reaction of a planar carbonyl function, the resultant cyanohydrins are
obtained as racemates. Starting from optically active α-hydroxyaldehydes the direct HCN addition7 as
well as the reaction of bisulfite adducts of α-hydroxyaldehydes with alkali cyanides gives only very
∗
†
Corresponding author. E-mail: franz.effenberger@po.uni-stuttgart.de
Part of dissertation, Universität Stuttgart, 1999.
0957-4166/99/$ - see front matter © 1999 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(99)00275-X

2818
J. Roos, F. Effenberger / Tetrahedron: Asymmetry 10 (1999) 2817–2828
poor asymmetric induction in cyanohydrin formation.8a,9 The cyanosilylation of optically active α-
hydroxyaldehydes affords 2,3-dihydroxynitriles with higher diastereoselectivities. The use of Lewis acid
catalysts8a,10 improves the threo/erythro ratio of the trialkylsilyl cyanide addition.
In recent years many investigations have demonstrated that hydroxynitrile lyase (HNL) catalyzed
additions of HCN to aldehydes proceed with high enantioselectivity.3a Depending on the applied HNL,
(R)- or (S)-cyanohydrins are thereby easily accessible. Because of the importance of stereoselective
syntheses of polyhydroxy and aminohydroxy compounds, we were interested to extend the HNL
catalyzed HCN addition also to α-hydroxyaldehydes as substrates in order to perform, for example,
a stereoselective Kiliani–Fischer synthesis. All investigations of this reaction have not so far been
successful. Neither free nor O-protected α-hydroxyaldehydes were found to be substrates for the enzyme
from bitter almonds ((R)-PaHNL).7,8a The (R)-PaHNL catalyzed HCN addition to phenoxyacetaldehyde
gave only the racemic product.11 Also under catalysis of (S)-HbHNL from the rubber tree (Hevea
brasiliensis) O-protected hydroxyaldehydes reacted with HCN to give only racemic cyanohydrins.12
Following our previous experience with the HNL catalyzed HCN addition to hydroxybenzaldehydes
where a strong dependence of enzymatic activity on the kind of protecting group has been found,13 we
have now investigated systematically the influence of protective groups on the HNL catalyzed addition
of HCN to O-protected α-hydroxyaldehydes.
1. Preparation of the O-protected 2-hydroxyaldehydes 3, 6 and 7
The addition of HCN to α-hydroxyaldehydes bearing bulky O-protecting groups is not catalyzed by
HNLs.7,8a,11,12 We have therefore investigated O-protecting groups which are as small as possible and
which can be removed easily under mild conditions (Scheme 1).
Scheme 1.
2-Benzyloxyacetaldehyde 3a was prepared analogous to a literature method.14 The protected gly-
colaldehydes 2-allyloxy- and 2-(β-methallyloxy)acetaldehyde 3b and 3c could be synthesized starting
from 2,3-O-isopropylideneglycerol 1 on the basis of a known procedure15 or alternatively from 2-

J. Roos, F. Effenberger / Tetrahedron: Asymmetry 10 (1999) 2817–2828
2819
methoxymethylenoxy- and tert-butyldimethylsilyloxyacetaldehyde 3d and 3e by O-alkylation of ethyl
hydroxyacetate 4 with alkyl halides 2 and subsequent reduction with DIBALH16 as outlined in Scheme 1.
According to this methodology the corresponding protected lactaldehydes 6a–d were prepared from L-
ethyl lactate L-5a17 which, as desired for some of our investigations, is racemized by NaH during the
reaction (Scheme 1). With an amine instead of NaH as base, however, as described for 6e, racemic
lactate 5a has to be used as starting compound.16c,d
Analogously the 2-allyloxyaldehydes 7a–c (with R1=Et, Pr, and Bu) were obtained from the correspon-
ding methyl 2-hydroxycarboxylates 5b–d (Scheme 1) which were prepared from the respective racemic
cyanohydrins via a Pinner reaction.
2. HNL catalyzed reaction of O-protected racemic hydroxyaldehydes 3, 6 and 7 with HCN
The O-protected glycol- and lactaldehydes 3 and 6 were reacted with HCN under catalysis of (R)-
PaHNL from Prunus amygdalus [EC 4.1.2.10] and (S)-MeHNL from Manihot esculenta [EC 4.1.2.37] to
give the cyanohydrins (2S)-, (2R)-8 and (2S,3RS)-, (2R,3RS)-9, respectively (Scheme 2, Tables 1 and 2).
In order to investigate the diastereoselectivity of the HNL catalyzed HCN addition, O-protected racemic
lactaldehydes 6 as well as 7, bearing the ethyl, propyl or butyl groups, were applied.
Scheme 2.
Table 1 shows for (R)-PaHNL a clear dependence of the enantiomeric excesses on the protecting
group. Aldehydes 3b and 3d, with the small allyl- and methoxymethylene protecting groups, react with
Table 1
Preparation of (2S)- and (2R)-cyanohydrins 8 by addition of HCN to the O-protected glycolaldehydes
3 catalyzed by (R)-PaHNL and (S)-MeHNL, respectively

2820
J. Roos, F. Effenberger / Tetrahedron: Asymmetry 10 (1999) 2817–2828
Table 2
Preparation of (2S,3RS)- and (2R,3RS)-cyanohydrins 9 by addition of HCN to the protected lactalde-
hydes 6 catalyzed by (R)-PaHNL and (S)-MeHNL, respectively
high stereoselectivity to yield (2S)-8b and (2S)-8d with 96% ee. Changing to the methallyl and the
benzyl protecting group the enantiomeric excess decreases significantly from 78% (8c) to 19% (8a). On
the contrary, using (S)-MeHNL as a catalyst, the methallyl-protected (2R)-8c was obtained with the best
enantiomeric excess (72%) but in only 40% yield, whereas the allyl derivative 8b results with only 38%
ee (65% yield).
As can be seen from Table 1, cyanohydrin formation using (R)-PaHNL as catalyst is more enantio-
selective than (S)-MeHNL catalysis. The dependence on the O-protecting group is less pronounced with
(S)-MeHNL as a catalyst. Table 1 reveals that neither the (R)- nor the (S)-HNL catalyzes the reaction
with the silylated aldehyde 3e. An inhibition of both enzymes by 3e itself can thereby be excluded, since
benzaldehyde, which is an excellent substrate for both enzymes, was converted to the respective (R)- and
(S)-cyanohydrin after addition to the reaction mixture of 3e.
The HNL catalyzed HCN addition to racemic lactaldehydes (RS)-6 is of interest not only with respect
to the enantioselectivity of cyanohydrin formation but also with respect to a kinetic resolution of the
racemate. Since, as shown later in Section 3, kinetic resolution does not occur. This problem, however,
will not be discussed further here.
Table 2 shows that the allyl protected lactaldehyde 6b was converted by both enzymes with the highest
enantiomeric excess to the corresponding cyanohydrins (2S,3RS)- and (2R,3RS)-8b, respectively. Also in
the case of lactaldehydes, (R)-PaHNL exhibits a higher stereoselectivity than (S)-MeHNL. Again, both
enzymes do not accept the silyl protected aldehyde 6e as a substrate.
Based on these results, the (R)-PaHNL and (S)-MeHNL catalyzed HCN addition to the O-allyl
protected 2-hydroxyaldehydes 7a–c, with R1=Et, Pr, and Bu, has been investigated. The results are
summarized in Table 3.
Table 3 shows stereoselective cyanohydrin formation with (R)-PaHNL as a catalyst. Obviously owing
to steric demand of the substrate with increasing chain length of R, the reaction is markedly decelerated
going from 7b to 7c. This tendency was also observed for reactions with (S)-MeHNL which again is less
stereoselective than (R)-PaHNL.
3. PaHNL catalyzed addition of HCN to the pure enantiomers (R)-6b and (S)-6b, respectively
The diastereoselectivity of cyanohydrin formation was investigated for the (R)-PaHNL catalyzed
addition of HCN to enantiomerically pure (R)- and (S)-2-allyloxypropionaldehyde (R)- and (S)-6b,

J. Roos, F. Effenberger / Tetrahedron: Asymmetry 10 (1999) 2817–2828
2821
Table 3
Preparation of (2S,3RS)- and (2R,3RS)-cyanohydrins 10 by addition of HCN to allyloxy protected
aldehydes 7 catalyzed by (R)-PaHNL and (S)-MeHNL, respectively
respectively (Scheme 3), prepared from commercial D-isobutyl and L-ethyl lactate according to the
literature.16a
Scheme 3.
The course of the HCN addition to both enantiomers was followed by gas chromatography (Fig. 1).
The conversion of the optically active aldehydes (R)- and (S)-6b proceeds with nearly identical reaction
rates as can be seen from Fig. 1. After ca. 23 h, the amount of resultant (2S,3S)-9b was ca. 90%
compared with ca. 80% of (2S,3R)-9b. Gas chromatographic analysis gave the same product ratio for
the reaction of the racemic aldehyde 6b. Thus, as shown for 6b, both HNLs investigated are not able to
Figure 1. (R)-PaHNL catalyzed addition of HCN to (R)-6b (ꢀ) and (S)-6b (ꢁ), respectively

2822
J. Roos, F. Effenberger / Tetrahedron: Asymmetry 10 (1999) 2817–2828
convert selectively only one enantiomer in a racemic mixture of O-protected α-hydroxyaldehydes to the
corresponding cyanohydrin.
Summarizing the HNL catalyzed additions of HCN to O-protected α-hydroxyaldehydes, the allyl
moiety was found to be the most suitable O-protective group. Using (R)-PaHNL as a catalyst high
enantiomeric excesses (≥93%) could be achieved whereas a maximum enantiomeric excess of 78% was
reached with (S)-MeHNL as catalyst. These results show that it is possible to prepare stereoselectively
dihydroxynitriles in a Kiliani–Fischer type reaction. In the conversion of the pure enantiomers of
allyloxypropionaldehyde (R)-6b and (S)-6b it could be demonstrated, for example, that both enantiomers
react with HCN under (R)-PaHNL catalysis with comparable reaction rates. Thus, a kinetic resolution of
racemic hydroxyaldehydes does not occur.
The configuration at C-2 in cyanohydrins 8–10 was confirmed by follow-up reactions of 6a to a known
amino deoxy sugar.18
4. HNL catalyzed HCN addition to O-protected (R)- and (S)-2,3-dihydroxyaldehyde 11
In order to perform a stereoselective Kiliani–Fischer synthesis we have investigated the enzyme
catalyzed addition of HCN to isopropylidene-protected (R)- and (S)-glyceraldehyde 11 (Scheme 4,
Table 4). Aldehyde (R)-11 is easily available from D-mannitol,19 and (S)-11 can be prepared starting
from L-ascorbic acid by a three-step procedure.20
Scheme 4.
The non-enzymatic addition of HCN to both (R)- and (S)-11 shows a stereopreference for the threo
diastereomer (2R,3R)- and (2S,3S)-12, respectively, with 19% de and 16% de (Table 4). The (R)-PaHNL
catalyzed reaction of (R)-11 with HCN yields the trihydroxynitrile (2S,3R)-12 with 60% de, whereas
the enantiomer (S)-11 reacts to give (2S,3S)-12 with 82% de. The higher diastereoselectivity of the (R)-
PaHNL catalyzed reaction of (S)-11 can be explained by also taking into account the chemical addition.
Table 4
Formation of (2S,3R)/(2S,3S)- and (2R,3R)/(2R,3S)-cyanohydrins 12 by HCN addition to protected
glyceraldehyde (R)- and (S)-11 catalyzed by (R)-PaHNL and (S)-MeHNL, respectively

J. Roos, F. Effenberger / Tetrahedron: Asymmetry 10 (1999) 2817–2828
2823
In the case of (S)-11 the stereo-induction is in the same direction as the (R)-PaHNL catalyzed reaction,
whereas in the case of (R)-11 it is inverse.
With (S)-MeHNL as catalyst the reaction of (R)-11 with HCN gives (2R,3R)-12 with 22% de, which
is in the range of the non-enzymatic chemical reaction (19% ee), whereas with (S)-11 only a very low
diastereoselectivity (7% de) for (2R,3S)-12 is observed. From these results a low activity of the enzyme
for the substrates (R)- and (S)-11 can be deduced. Therefore the diastereoselectivity of the non-enzymatic
reaction compensates the enzyme catalyzed reaction.
The configuration of the stereogenic centre generated at C-2 could be established by comparison of
13C NMR spectra of commercially available pure D-erythronic acid γ-lactone and that derived from
(2S,3R)-12 by treatment with conc. HCl.
5. Experimental
5.1. Materials and methods
Benzyloxyacetaldehyde 3a was prepared according to a literature method.14 D-Isobutyl lactate was
purchased from Degussa AG, L-ethyl lactate from Fluka, and D-erythronic acid γ-lactone from Aldrich.
Melting points were determined on a Büchi SMP-20 and are uncorrected. 1H NMR spectra were recorded
on a Bruker AC 250 F (250 MHz) and ARX 500 (500 MHz) with TMS as internal standard. Optical
rotations were determined in a Perkin–Elmer polarimeter 241 LC. GC for determination of enantiomeric
and diastereomeric excess: (a) Hewlett–Packard 5890 Series II with FID, 0.45 bar hydrogen, column 30
m×0.32 mm, phase OV 1701; (b) Hewlett–Packard 6890 Series with FID, 0.9 bar hydrogen, column 30
m×0.32 mm, phase Chiraldex B-TA (ICT); (c) Carlo Erba MRGC 5300 Mega Series with FID, 0.4 bar
hydrogen, column 20 m, phase Bondex-unβ-5.5-Et-105.
5.2. Preparation of allyl- and methallyloxyacetaldehydes 3b,c from glycerol 1: general procedure
(a) According to known methods15 a solution of 1 (0.11–0.2 mol) in THF (100–200 mL) was added
dropwise to a suspension of NaH (0.13–0.24 mol) in THF (250–500 mL), and the reaction mixture was
heated to reflux for 30 min. After cooling to room temperature, ca. 1.2 equivalents of 2b or 2c were
added, and the reaction mixture was refluxed for a further 12 h. The solvent was removed, the residue
taken up in diethyl ether, and precipitated sodium halide filtered off. The filtrate was dried (MgSO4)
and concentrated. The residue was fractionally distilled to give 1-allyloxy- and 1-(β-methallyloxy)-2,3-
isopropylideneglycerol in 77% and 78% yield, respectively.
1
1-(β-Methallyloxy)-2,3-isopropylideneglycerol: bp 83°C/10 torr; H NMR (CDCl3): δ=1.37, 1.43
(each s, 3H, C(CH3)2), 1.73 (s, 3H, CH3), 3.39–4.33 (m, 7H, 3 CH2, CH), 4.90–4.96 (m, 2H, _CH2).
(b) For removal of the isopropylidene protecting group a solution of the respective acetal (see above)
(54–81 mmol) in 2N HCl/THF (10–30 mL/100–120 mL) was stirred at room temperature for 20–28 h
(TLC control). The reaction mixture was then neutralized with solid NaHCO3, and THF was removed.
Dichloromethane was added followed by an equimolar solution (based on acetal) of NaIO4 in water
(100–130 mL) under ice cooling. After being stirred for 12 h at room temperature, the organic phase was
separated and the aqueous layer extracted three times with dichloromethane (70 mL each). The combined
organic phases were dried (MgSO4) and concentrated. The residue was distilled in vacuo to give 3b14b
and 3c in 60 and 58% yield, respectively.

2824
J. Roos, F. Effenberger / Tetrahedron: Asymmetry 10 (1999) 2817–2828
5.3. Preparation of protected hydroxyacet- and propionaldehydes 3c,d and 6a–d from 4 and L-5a,
respectively: general procedure
(a) According to Drewes et al.17 a solution of 4 or L-5a in THF was slowly added dropwise to a
suspension of NaH in THF, and the reaction mixture was heated to 60°C for 30 min. Then a solution of
2 in THF was added dropwise. After being heated to reflux for 12 h, THF was removed and the residue
taken up in diethyl ether. Sodium halide was filtered off, and the filtrate was dried (MgSO4), concentrated
and distilled in vacuo.
1
Ethyl methallyloxyacetate: bp 75°C/10 torr; H NMR (CDCl3): δ=1.29 (t, J=7.1 Hz, 3H, CH2CH3),
1.76 (s, 3H, CH3), 4.00, 4.05 (each s, 2H, CH2), 4.23 (q, 2H, CH2CH3), 4.94–4.99 (m, 2H, _CH2).
1
Ethyl methoxymethylenoxyacetate: bp 66°C/13 torr; H NMR (CDCl3): δ=1.30 (t, J=7.2 Hz, 3H,
CH2CH3), 3.41 (s, 3H, CH3O), 4.16 (s, 2H, CH2), 4.24 (q, 2H, CH2CH3), 4.72 (s, 2H, OCH2O).
1
Ethyl 2-methallyloxypropionate: H NMR (CDCl3): δ=1.29 (t, J=7.1 Hz, 3H, CH2CH3), 1.42 (d,
J=6.8 Hz, 3H, CHCH3), 1.76 (s, 3H, CH3), 3.81–4.08 (m, 3H, CH, CH2), 4.21 (q, 2H, CH2CH3),
4.91–4.98 (m, 2H, _CH2).
(b) Analogous to known procedures,16a,c to a solution of the respective protected ester in diethyl ether
or n-hexane:THF (95:5) at −78°C a 1 M solution of DIBALH in n-hexane (ca. 1.1–1.4 equivalents) was
slowly added dropwise, and the reaction mixture was stirred for 4–6.5 h at −78°C. After hydrolysis with
water, the reaction mixture was allowed to warm to room temperature. Aluminium hydroxide was filtered
off through a glass frit and washed with diethyl ether. The combined filtrates were dried (MgSO4), and
concentrated. The residue was distilled in vacuo to yield aldehydes 3c,d and 6a–d.16a,d,17
5.4. Preparation of silylated hydroxyaldehydes 3e and 6e from 4 and 5a: general procedure
To a solution of 4 or 5a and diisopropylethylamine in dichloromethane at 0°C 2e was added dropwise.
The reaction mixture was allowed to warm to room temperature (12 h) and washed with 1N HCl, water,
sat. NaHCO3 solution and water (50 mL each). The organic phase was dried (MgSO4), and concentrated.
The residue was distilled in vacuo. The reduction to aldehyde 3e21 and 6e,16c respectively, was performed
as described above under Section 5.3.b.
5.5. Preparation of allyl protected hydroxyaldehydes 7a–c
(a) A solution of the respective racemic cyanohydrin in methanolic HCl was heated in a sealed tube to
90°C for 8 h. After being cooled to room temperature, the reaction mixture was hydrolyzed with water
(20 vol%) and extracted with diethyl ether (50 mL each). The combined extracts were washed with sat.
NaHCO3 solution until neutral, dried (MgSO4), and concentrated. The residue was distilled in vacuo to
give esters 5b–d.
(b) The allyl protecting group was introduced in 5b–d as described above in Section 5.3.a.
1
Methyl 2-allyloxybutyrate: bp 63°C/10 torr; H NMR (CDCl3): δ=0.97 (t, J=7.4 Hz, 3H, CH3),
1.72–1.85 (m, 2H, C3H2), 3.75 (s, 3H, OCH3), 3.80–4.20 (m, 3H, CH2, CH), 5.17–5.33 (m, 2H, _CH2),
5.84–5.99 (m, 1H, _CH).
1
Methyl 2-allyloxypentanoate: bp 75°C/10 torr; H NMR (CDCl3): δ=0.93 (t, J=7.3 Hz, 3H, CH3),
1.36–1.79 (m, 4H, (CH2)2), 3.75 (s, 3H, OCH3), 3.83–3.94 (m, 2H, CH2), 4.11–4.19 (m, 1H, CH),
5.17–5.33 (m, 2H, _CH2), 5.83–5.99 (m, 1H, _CH).

J. Roos, F. Effenberger / Tetrahedron: Asymmetry 10 (1999) 2817–2828
2825
Table 5
Physical and 1H NMR data of protected hydroxyaldehydes 3, 6 and 7a
1
Methyl 2-allyloxyhexanoate: bp 92°C/10 torr; H NMR (CDCl3): δ=0.90 (t, J=5.8 Hz, 3H, CH3),
1.28–1.46 (m, 4H, (CH2)2), 1.64–1.79 (m, 2H, C3H2), 3.75 (s, 3H, OCH3), 3.83–4.19 (m, 3H, CH2, CH),
5.17–5.33 (m, 2H, _CH2), 5.83–5.99 (m, 1H, _CH).
(c) Aldehydes 7 were prepared from allyl protected esters (Section 5.5.b) as described above in
Section 5.3.b.
The NMR data and elemental analyses for compounds 3, 6–10 are given in Tables 5 and 6.
5.6. Enzyme catalyzed preparation of optically active cyanohydrins 8–10
Compounds (2S)-8 and (2S,3RS)-9, 10 as well as (2R)-8 and (2R,3RS)-9, 10 were prepared by (R)-
PaHNL [EC 4.1.2.10] and (S)-MeHNL [EC 4.1.2.37] catalyzed addition of HCN to aldehydes 3, 6 and 7
analogous to literature procedures.23
5.7. Determination of enantiomeric excesses
A solution of cyanohydrin (10 µL), pyridine (10 µL) and acetic anhydride (50 µL) in 0.5 mL
dichloromethane was heated to 60°C for 5 h. The reaction mixture was filtered through a silica gel
column (3×0.5 cm) with ca. 4 mL dichloromethane. Enantiomeric and diastereomeric excesses were
determined by gas chromatography directly from the filtrate. The acetylated derivatives were also used
for elemental analyses.

2826
J. Roos, F. Effenberger / Tetrahedron: Asymmetry 10 (1999) 2817–2828
Table 6
NMR data of protected cyanohydrins 8–10 and elemental analysis of acetylated cyanohydrins ac 8–10

J. Roos, F. Effenberger / Tetrahedron: Asymmetry 10 (1999) 2817–2828
2827
5.8. Enzyme catalyzed preparation of trihydroxynitrile 12 from protected (R)- and (S)-glyceraldehyde
11
(a) (R)- and (S)-11 was reacted with HCN in diisopropyl ether under (R)-PaHNL and (S)-MeHNL
catalysis as described in the literature23 to yield the respective diastereomers 12.
20
1
(2S,3R)-12: [α] =−15.5 (c 1.15, CHCl3), 60% de; H NMR (CDCl3): δ=1.39, 1.51 (each s, 3H,
D
CH3), 3.37 (bs, 1H, OH), 3.99–4.21 (m, 2H, C4H2 interfered), 4.32–4.38 (m, 1H, C3H interfered), 4.42
(d, J=5.6 Hz, 1H, C2H).
(2S,3S)-12: [α]20=+9.43 (c 1.4, CHCl3), 82% de; 1H NMR (CDCl3): δ=1.40, 1.51 (each s, 3H, CH3),
D
3.23 (bs, 1H, OH), 4.02 (dd, J=5.1, 9.3 Hz, 1H, C4H2), 4.18 (dd, J=6.6 Hz, 1H, C4H2), 4.35 (dt, 1H,
C3H), 4.49 (d, J=4.5 Hz, 1H, C2H). MS (Auto CI, 70 eV) for C7H11NO3: calcd (MH+) 158.0817; found
158.0814. MS: m/z (%): 158.1 (1) [MH+], 142.1 (52) [M−CH3], 101.0 (29) [dioxolane], 43.0 (100), 28.0
(25).
5.9. Preparation of D-erythronic acid γ-lactone from (2S,3R)-12
A solution of (2S,3R)-12 (146 mg, 0.93 mmol) in conc. HCl (6 mL) was heated to 60°C for 3 h. The
reaction mixture was evaporated, and the residue was extracted three times with ethyl acetate (5 mL
each). The combined extracts were concentrated to give 77 mg (61%) D-erythronic acid γ-lactone.
Acknowledgements
This work was supported by the Bundesministerium für Bildung und Forschung (Zentrales Schwer-
punktprogramm Bioverfahrenstechnik, Stuttgart).
References
1. Enzyme-Catalyzed Reactions. Part 37. Part 36: Gaupp, S.; Effenberger, F. Tetrahedron: Asymmetry 1999, 10, 1777–1786.
2. (a) Kiliani, H. Ber. Dtsch. Chem. Ges. 1885, 18, 3066–3072. (b) Kiliani, H. Ber. Dtsch. Chem. Ges. 1887, 20, 339–346. (c)
Fischer, E. Ber. Dtsch. Chem. Ges. 1889, 22, 2204–2205.
3. (a) Effenberger, F. Angew. Chem., Int. Ed. Engl. 1994, 33, 1555–1564. (b) Brussee, J.; Dofferhoff, F.; Kruse, C. G.; van
der Gen, A. Tetrahedron 1990, 46, 1653–1658.
4. Forth, W.; Henschler, D.; Rummel, W. Pharmakologie und Toxikologie; 5th ed.; Wissenschaftsverlag: Mannheim, 1988.
5. Sham, H. L.; Rempel, C. A.; Stein, H.; Cohen, J. J. Chem. Soc., Chem. Commun. 1990, 666–667.
6. (a) Arcamone, F.; Franceschi, G.; Orezzi, P.; Cassinelli, G.; Barbieri, W.; Mondelli, R. J. Am. Chem. Soc. 1964, 86,
5334–5335. (b) Arcamone, F.; Cassinelli, G.; Orezzi, P.; Franceschi, G.; Mondelli, R. J. Am. Chem. Soc. 1964, 86,
5335–5336.
7. Effenberger, F.; Hopf, M.; Ziegler, T.; Hudelmayer, J. Chem. Ber. 1991, 124, 1651–1659.
8. (a) Hopf, M. Dissertation; Universität Stuttgart, 1990. (b) Althoff, W.; Karsdorf, R.; Tinapp, P. Arch. Pharm. 1981, 314,
518–524.
9. Matthews, B. R.; Gountzos, H.; Jackson, W. R.; Watson, K. G. Tetrahedron Lett. 1989, 30, 5157–5158.
10. (a) Reetz, M. T.; Kessler, K.; Jung, A. Angew. Chem., Int. Ed. Engl. 1985, 24, 989–990. (b) Reetz, M. T.; Fox, D. N. A.
Tetrahedron Lett. 1993, 34, 1119–1122. (c) Ipaktschi, J.; Heydari, A. Chem. Ber. 1993, 126, 1905–1912. (d) Gu, J.-H.;
Okamoto, M.; Terada, M.; Mikami, K.; Nakai, T. Chem. Lett. 1992, 1169–1172.
11. Brussee, J.; Loos, W. T.; Kruse, C. G.; van der Gen, A. Tetrahedron 1990, 46, 979–986.
12. Schmidt, M.; Hervé, S.; Klempier, N.; Griengl, H. Tetrahedron 1996, 52, 7833–7840.
13. (a) Jäger, J. Dissertation; Universität Stuttgart, 1996. (b) Effenberger, F.; Jäger, J. J. Org. Chem. 1997, 62, 3867–3873.

2828
J. Roos, F. Effenberger / Tetrahedron: Asymmetry 10 (1999) 2817–2828
14. (a) Grob, C. A.; Reber, F. Helv. Chim. Acta 1950, 33, 1776–1787. (b) Sumitomo, H.; Hashimoto, K.; Kitao, O. J. Polym.
Sci. 1975, 13, 327–336.
15. Shiao, M.-J.; Yang, C.-Y.; Lee, S.-H.; Wu, T.-C. Synth. Commun. 1988, 18, 359–366.
16. (a) Aurich, H. G.; Biesemeier, F.; Boutahar, M. Chem. Ber. 1991, 124, 2329–2334. (b) Hoppe, D.; Tarara, G.; Wilckens,
M. Synthesis 1989, 83–88. (c) Massad, S. K.; Hawkins, L. D.; Baker, D. C. J. Org. Chem. 1983, 48, 5180–5182. (d) Banfi,
L.; Bernardi, A.; Colombo, L.; Gennari, C.; Scolastico, C. J. Org. Chem. 1984, 49, 3784–3790.
17. Drewes, S. E.; Manickum, T.; Roos, G. H. P. Synth. Commun. 1988, 18, 1065–1070.
18. Effenberger, F.; Roos, J. in preparation.
19. Schmid, C. R.; Bryant, J. D.; Dowlatzedah, M.; Phillips, J. L.; Prather, D. E.; Schantz, R. D.; Sear, N. L.; Vianco, C. S. J.
Org. Chem. 1991, 56, 4056–4058.
20. Hubschwerlen, C. Synthesis 1986, 962–964.
21. Sodeoka, M.; Yamada, H.; Shibasaki, M. J. Am. Chem. Soc. 1990, 112, 4906–4911.
22. Solladié-Cavallo, A.; Bonne, F. Tetrahedron: Asymmetry 1996, 7, 171–180.
23. (a) Förster, S.; Roos, J.; Effenberger, F.; Wajant, H.; Sprauer, A. Angew. Chem., Int. Ed. Engl. 1996, 35, 437–439. (b)
Effenberger, F.; Eichhorn, J.; Roos, J. Tetrahedron: Asymmetry 1995, 6, 271–282.