The Final Structures of the Lichen Chromones Galapagin, Lobodirin, Mollin, and Roccellin

Abstract

The structures of the lichen chromones galapagin, lobodirin, mollin, and roccellin, specific com­ pounds of Roccellaceae (lichens), have been es­ tablished as 1, 2, 3, and 4, respectively, by NOE difference spectroscopoy.

Full text

Notizen 449
The Final Structures of the Lichen
Chromones Galapagin, Lobodirin, Mollin,
and Roccellin
Siegfried Hune ck*3, Jasmin Jak upov ic b, and
Gerhard F ollm annc
a Institu te o f Plant B iochemistry,
Weinberg 3, D-0 -4 050Halle /S aale
b Institute o f Organic Chemistry,
Techn ica l Un iversity , Straße des 17. Juni 135,
D -W -1000 Berlin 12
c Botan ical Institute, U niversity o f Cologne,
Gyrhofstraße 1 5,D -W -500 0K öln41
Z. N aturforsch . 47b, 4 49 -451 (1992);
received July 15,1991
Lichens, Chrom on e Glucos ides,
NOE Difference Spectra
The stru ctures of the lichen chromo ne s gala pa 
gin, lob od irin, mollin, and roccellin, specific co m 
pounds o f Rocce llaceae (lic hens), have been es
tablished as 1, 2, 3, and 4, respectively, by NOE
difference spec troscopoy.
In 1972 and 1973, Huneck described the isola
tion of roccellin, m ollin, galapagin [1], and lobodi
rin [2], hitherto know n only from certa in taxa of
Roccellaceae (Ascolichenes), an d recognized these
compounds as partially acetylated chromon e glu
cosides. The position o f the acetyl groups could
not be determ in ed at th at time. Now we have eluci
dated the full structures of these lichen chrom ones
by application of N O E difference spectroscopy
and re port here on our results.
Galap agin is 8-methyleugenitol-7-0-/?-D -6'-
O-acetyl-glucopyranoside (1), because the 'H
NM R spectrum shows three do ublets a t S 5.68,
5.21, an d 5.26 ppm, corresponding to the hydroxyl
groups at C-2', C-3', and C-4' (Table I).
Lo bodirin is isoeugenitol-7-0-/?-D-2',3',6'-tri-
O-acetyl-glucopyranoside (2), because there is the
doublet of the free 4'-O H-g roup which is coupled
with the 4'-proton.
Mollin is a derivative of eugenitol and shows no
2'-OH signal in its 'H N M R spectrum (in DMSO-
d6). Because there is only one signal of an acetyl-
Me group, the acetoxy group must be situated at
C-2', which m eans tha t mollin is eugenitol-7-O-
/?-D-2'-0-acetyl-glucop yranoside (3).
The 'H N MR spektru m o f roccellin reveals 2
singulets of 2 acetyl-M e gro ups at 1.90 and 2.08
ppm (in DM SO-d6) and 2.11 and 2.17 ppm (in
* Reprint requests to Dr. S. Huneck.
Verlag der Ze itsc hrift für Naturf ors chung ,
D -W -7400 T üb in gen
0932-0 77 6/92 /0300-4 49 /$ 01.00/0
CDC13), respectively, but no signals o f the 2'- and
6'-OH groups; hence roccellin is eugenitol-7-O-
/?-D-2',6'-di-0-acetyl-glucopyranoside (4). The
methyl signals in the ‘H NM R spectrum of acetyl-
roccellin (5) could be correlated by their chemical
shifts and NOE difference spectra. Th e m ethyl
group corresponding to the singulet at 2.30 pp m
gives a NOE with the proton at C-3 and hence is
the methyl group at C-2. N OE ’s are also observed
between the acetyl-M e group at C-5 (s 2.45 ppm )
and the M e-group at C-6 (s 2.02 ppm).
13C NM R data o f galapagin, mollin, a nd acetyl-
roccellin are given in Table II.

450 N o ti ze n
Table I. 'H N MR chem ical shifts and coupling constants o f galap agin (1), lobo dirin (2), mollin (3), roccellin (4), and
acetylroccellin (5).
11234 4 5
400 MHz 400 MH z 400 M Hz 250 MHz 400 M Hz 400 MHz 400 M Hz
D M SO -d 6ac etone-d6C DC lj D M SO -d 6D M SO -d 6CDC13C DCI3
H-3 s 6.27 q 6.16 s 6.05 s 6.27 s 6.26 s 6.06 s 5.99
H-6 --s 6.48 -- - -
H-8 -- - s 6.76 s 6.74 s 6.56 s 6.89
H -l' d 4.64 d 4.79 d 5.09 d 5.32 d 5.30 d 5.03 d 5.12
H-2' m 3.34 m 3.57 dd 5.31 dd 4.87 dd 4.88 dd 5.18 dd 5.38
H-3' ddd 3.25 m 3.50 dd 5.14 m 3.53 ddd 3.55 ddd 3.76 dd 5.33
H-4' ddd 3.18 m 3.42 ddd 3.67 ddd 3.28 ddd 3.30 ddd 3.58 dd 5.17
H-5' m 3.30 m 3.42 ddd 3.74 m 3.50 ddd 3.84 ddd 3.71 dt 3.98
H-6', jm 4.11 jm 4.24 dd 4.38 m 3.50 dd 4.08 dd 4.40 jd 4.26
H-6'2 dd 4.54 dd 3.75 dd 4.38 dd 4.55
C-2-Me s 2.42 d 2.45 s 2.39 s 2.39 s 2.38 s 2.35 s 2.30
C-6-Me s 2.13 s 2.19 -s 2.03 s 2.11 s 2.05 s 2.02
C-8-M e s 2.16 s 2.31 s 2.16 - - - -
5-OH s 12.92 s 12.97 s 12.67 s 13.05 s 13.01 s 12.85 -
2'-OH d 5.68 d 4.84 -- - - -
3'-OH d 5.21 d 4.43 -d 5.45 d 5.56 d 2.78 -
4'-OH d 5.26 d 4.49 d 3.07 d 5.35 d 5.61 d 3.09 -
6'-OH - - - dd 4.73 - - -
2'-OAc - - s 2.07 s 1.89 s 2.08 s 2.17 s 2.08
3'-OAc - - s 2.09 - - - s 2.07
4'-OAc - - - - - - s 2.06
6'-OAc s 1.89 s 1.89 s 2.14 -s 1.90 s 2.11 s 2.13
/(H z): l',2' = 7.5; 2',3' = 3',4' = 4',5' ~ 9.5; 5' ,6/ = 2.5; 5',62' = 5; 6,',62' = 12; 2',OH = 3',OH = 6',OH ~ 5.
Table II. I3C N M R chem ical shifts o f galapa gin (1), mollin (3), and acety lroccellin (5). Shifts marked a and b may be
interchangeable.
Co mpound
C A tom 1 (67.9 MH z, DM SO- d6) 3 (62.76 MHz , DM SO-d6) 5 (67.9 M Hz, D MS O-d 6)
2 (C ) 168.44 168.39 169.10
3 (C H) 108.04 108.37 111.61
4 (CO) 182.67 182.27 176.25
5 (C ) 152 .56a 158.1 3 156.52
6(C) 109.70 108.51 119.00
7 (C ) 158 .51 a 155.55 147.81
8 (C ,C H) 114.31 97 .72b 100.50
9 (C ) 155.9 3 160.28 158.48
10 (C ) 106.54 105.00 112.15
11(CH3) 8.84 6.92 8.49
12 (C H3) 8.89 - -
13 (C H3) 20.04 19.88 20.00
l' (C H ) 104.26 93 .10b 98.59
2! (CH) 76.04 77.34 72.40
3' (CH) 73.91 74.54 72.38
4' (C H) 69.97 69.74 68.26
5' (CH) 73.36 73.31 70.69
6' (C H 2) 63.05 60.51 61.96
2 '-O C O - C H 3-20.69
6'- O C O -C H 320.37 -10.57 (4x )
3 '-O C O -C H 3--10.98
4 '-O C O - C H 3--
2 '-O C O -C H 3-169.59
6'- O C O -C H 3170.06 -170.40 (2x)
3 '-O C O -C H 3- - ‘170.41
4 '-O C O - C H 3—-169.38 (2x )

Notizen 451
NOE’s in the form ulae 1 -5 are marked by arrows.
Experimental
The N M R spectra were recorded on Bruker AM
400, AM 270, and 250 M Hz instruments.
Galapagin (1)
MS, m /z 466.1475 (M +; calcd for C22H26O n :
466.1475), 424.13693 (M -C H 2=C = 0 ; calcd for
C20H24O ,0: 424.13693), 220.0733 ([8-methyleugeni-
tol]t; calcd for C 12H120 4: 220.0735).
Roccellin (4)
MS, m /z 206.0577 ([eugenitol]T; calcd for
C n H 10O4: 206.0579).
S. H. thanks the Fonds der Chem ischen Industrie
(Frankfurt/Main ) for financial support; G. F. gratefully
acknow ledges a travel grant of the Association o f Pro
mo ters of the University of Cologne for a lichen co llect
ing trip to South America in 1989.
[1] S. H uneck, J. Prakt. Chem. 3 14,48 8 (1 97 2). [2] S. Hu neck, Phytochemistry 12, 2497 (1973).