The photodecarboxylative addition of carboxylates to phthalimides: Scope and limitations

Article abstract of DOI:10.3987/COM-02-S77

Intermolecular photoinduced decarboxylative additions of a series of alkylcarboxylates to N-substituted phthalimides gave the corresponding hydroxyphthalimidines in moderate to high yields of 39-89%. The potassium salt of 1-adamantanecarboxylic acid predominately underwent simple decarboxylation when irradiated in the presence of N-methylphthalimide. In case of phthalimides carrying suitable leaving groups within the N-side chain, decarboxylation, retro-Aldol cleavage or decarbonylation preceded the intermolecular addition step.

Full text of DOI:10.3987/COM-02-S77

HETEROCYCLES, Vol. 59, No. 2, 2003, pp. 669 - 684, Received, 25th October, 2002
THE PHOTODECARBOXYLATIVE ADDITION OF CARBOXYLATES
TO PHTHALIMIDES: SCOPE AND LIMITATIONS#
Michael Oelgemöller, Peter Cygon, Johann Lex, and Axel G. Griesbeck*
Institute of Organic Chemistry, University of Cologne, Greinstrasse 4, D-50939
Köln, Germany. E-mail: griesbeck@uni-koeln.de
Abstract – Intermolecular photoinduced decarboxylative additions of a series of
alkylcarboxylates to N-substituted phthalimides gave the corresponding hydroxy-
phthalimidines in moderate to high yields of 39-89%. The potassium salt of 1-
adamantanecarboxylic acid predominately underwent simple decarboxylation
when irradiated in the presence of N-methylphthalimide. In case of phthalimides
carrying suitable leaving groups within the N-side chain, decarboxylation, retro-
Aldol cleavage or decarbonylation preceded the intermolecular addition step.
INTRODUCTION
Since the pioneering work of Kanaoka and coworkers in the early 1970'ies,1 the photochemistry of
phthalimides has attracted growing attention in terms of synthetic organic photochemistry.2 Among the
numerous intermolecular applications, addition reactions of alkenes,3 alcohols,4 ethers,3d,5 thioethers,6
alkylbenzenes,7 and amines7b to the phthalimide system have been reported. In many cases, however,
these reactions gave poor yields, and mixtures of the desired photoaddition and photoreduction products
were obtained. During our ongoing studies on intramolecular photodecarboxylative cyclization reactions
of ω-phthalimidoalkylcarboxylates, we found that the alkylcarboxylate anion can be used as a powerful
activating and directing group, and developed a suitable method for the synthesis of various macrocyclic
systems in good to high yields.8 As an extension of this concept, we have briefly described a corre-
sponding intermolecular addition version leading to Grignard reaction-alike products.9 To further explore
the scope and limitation of this addition reaction, we have investigated several carboxylate/phthalimide
systems in detail. An important aspect was a mild and convenient photochemical pathway to hydroxy-
#
Dedicated to Prof. Yuichi Kanaoka on the occasion of his 75th birthday.

phthalimidines, which were previously commonly synthesized via thermal methods, e.g. SmI2-mediated
coupling of organic halides (SmI2/R-X),10a addition of organometallic compounds (R-Mg-X or R-Li),10b-d
or alkylation with organic halides using lithium in liquid ammonia (Li/NH3/R-X),10e respectively.
RESULTS AND DISCUSSION
In a first series of experiments N-methylphthalimide (1a) was used as a model substrate and the carboxy-
late compound (2a-i) was varied. Upon irradiation in aqueous acetone and in the presence of 3-6 equiva-
lents of the potassium carboxylate, the corresponding hydroxyphthalimidines (3a-h) were obtained in
moderate to good yields of 39-89%. Solely potassium benzoate (2i) remained unreactive and N-methyl-
phthalimide (1a) was reisolated in 86% yield even after prolonged irradiation. From the carboxylate (2d)
a mixture of diastereoisomers with low d.e. of 10% was obtained. Other N-substituted phthalimides (1b-
e) were investigated using potassium propionate (2b) as the alkylating reagent and similar hydroxy
phthalimidines (3j-m) were obtained in yields of 52-88%. Unlike alternative thermal additions (e.g.
Grignard reactions10b,c), other carbonyl groups as in substrates (1d) and (1e) were tolerated and photo-
induced alkylation occurred regioselectively at the imide chromophore and not at the ester or amide
carbonyl group. The general reaction is outlined in Scheme 1 and selected experimental details are sum-
marized in Table 1.
O
R2
HO
hν
R1
CO2K
N
R1
R2
N
+
acetone / water
O
O
3 (39-89%)
1
2
Scheme 1
The reaction process was easily monitored by TLC analysis or by passing a stream of nitrogen gas
through the reaction mixture and subsequently into a saturated barium hydroxide solution until precipita-
tion of barium carbonate has ceased. Best results were obtained with 20% aqueous acetone as solvent and
5 equivalents of carboxylate. An excess amount of carboxylate was required in order to drive the reaction
to high conversion. For most experiments, a Rayonet reactor equipped with mercury low pressure lamps
(phosphor coated with an emission maximum at 300 nm; 800 W) was used but alternatively a high pres-
sure mercury lamp (400 W) served as an efficient light source.
Recrystallization from acetone gave suitable crystals of 3h and 3l for X-Ray crystallographic analysis
and the structures are shown in Figure 1.

Table 1 Photodecarboxylative additions of potassium carboxylates (2) to phthalimides (1).
Substrates
R1 (amount [g])
Conditions
Photoproduct
1
2
R2
acetone/
H2O [mL]
light-
time conv. 1
3
yield 3
sourcea
[%]b
(amount [g])
[h]
[%]
39 (93b)
88
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1b
1c
Me (0.32)
Me (0.36)
2a
2b
2c
2c
2d
2e
2f
Me (1.0)
Et (1.0)
4:1 (200)
9:1 (200)
9:1 (150)
1:3 (2000)
4:1 (300)
4:1 (300)
4:1 (300)
4:1 (300)
A
A
A
B
C
C
A
C
A
A
A
A
A
41
23
23
4 ¼
1 ½
1 ½
23
1
42
3a
3b
3c
3c
3d
3e
3f
100
100
73
Me (0.28)
i-Pr (0.7)
i-Pr (30.3)
s-Bu (1.4)
i-Bu (1.4)
t-Bu (1.4)
t-Bu (1.4)
86
63 (86c)
89 (10d)
51 (60c)
57
Me (6.45)
Me (0.32)
100
85
Me (0.32)
Me (0.32)
100
89
76 (85c)
Me (0.32)
2f
3f
Me (0.22)
2g
2h
2i
CH2-t-Bu (1.2) 9:1 (150)
23
20
48
24
23
100
100
0 (86e)
60
3g
3h
3i
80
Me (0.35)
Bn (1.3)
Ph (1.6)
Et (1.0)
Et (0.6)
9:1 (200)
9:1 (200)
4:1 (200)
4:1 (300)
88
Me (0.35)
0
55 (92c)
Ph (0.45)
2b
2b
3j
CH2C≡CH (0.19)
CH2CO2Me (0.41)
100
3k
88
1d
1e
2b
2b
Et (1.1)
Et (1.0)
4:1 (300)
9:1 (200)
A
A
17
17
100
100
3l
88
52
CH2CONHCH2CO2Me
(0.52)
3m
a A: Rayonet (300 ± 10 nm); B: XeCl excimer (308 nm); C: High-pressure mercury lamp (400 W). b Determined by 1H NMR
spectroscopy or GC analysis of the crude product. c Yield based on conversion. d d.e. (unlike-/like-3d). e Reisolated 1.
3h
3l
Figure 1 Structures of 3h and 3l in the crystal.
As a side-reaction of the intramolecular cyclization version, the formation of simple decarboxylation
products (CO2 /H-exchange) was commonly observed.8 Similarly, simple decarboxylation was expected to
-
compete with the addition reaction. From these side-reactions, volatile alkanes were expected to be
formed which escaped from the reaction mixture and could not be detected after work-up. However,
when the potassium salt of 1-adamantanecarboxylic acid (2j) was used the corresponding alkane
adamantane (4) was isolated as main product in yields of 60-69%. Most of the N-methylphthalimide (1a)

remained unchanged and could be reisolated. In one exemplary case 1a and unreactive carboxylic acid
were recovered in yields of 78% and 37%, respectively, whereas the photoaddition product (3n) was ob-
tained in 2% yield next to 60% of 4. Hence, in case of 1-adamantanecarboxylic acid the phthalimide acts
as a catalyst for an electron shuttle process.
O
HO
hν
N
Me
N Me
+
+
CO2K
H
acetone / water
O
O
3n (2%)
1a
2j
4 (60-69%)
Scheme 2
As a model reaction for a large scale preparation, the photodecarboxylative addition of potassium iso-
butyrate (2c) to 1a was performed using a falling-film apparatus equipped with a 308 nm XeCl excimer
light source (Scheme 3).11 This reaction proceeded smoothly on a multigram scale in a 3:1 (vol %) water-
acetone mixture using 6 equivalents of the alkyl carboxylate and a 0.02 M solution of phthalimide (1a).
The reaction progress was monitored by continuous pH control and gas chromatographic determination
of the substrate/product ratio (1a/3c).
O
HO
hν308nm
N
Me
N Me
+
CO K
2
acetone / water
73% conversion
O
O
1a
2c
3c (63%)
100
80
60
40
20
0
8.0
7.5
7.0
6.5
1a
3c
0
50
100
150
200
250
0
50
100
150
200
250
Time [min]
Time [min]
Scheme 3
The photoaddition protocol was furthermore expanded to phthalimides (5) carrying photochemically
labile side-chains (indicated as X). In all cases examined, irradiation in the presence of potassium pro-

pionate (2b) led to cleavage of the photo-labile group prior to alkylation (Scheme 4; Table 2). These
extrusion processes also occurred in the absence of carboxylate as proven by independent runs under
similar conditions. However, the conversions were significantly lower for 5c and 5e in the latter cases.
The phthaloylated α-amino acids (5a) and (5b) underwent rapid α-decarboxylation, a process originally
discovered by Kanaoka and coworkers.12 The phthalimidopropanol derivative (5c) showed retro-Aldol
cleavage,13 whereas decarbonylation or elimination of malonic acid diester preceded the photoinduced
alkylation for phthalimides (5d) and (5e), respectively.
O
O
HO
X
R
hν
N
CO K
N
N
+
+
2
acetone / water
R
R
O
O
O
3b,o (33-93%)
5a-e
2b
1a,f
Scheme 4
Table 2 Photoreactions involving phthalimides (5a-e).
Substrates
Conditions
Photoproducts
yields [%]
5
X
R
5
2b
acetone/ time conv. 5
[%]a
100
100
100
100
100
5
amount [g] amount [g] H2O [mL] [h]
5a
5a
5b
5b
5c
5c
5d
5d
5e
5e
CO2H
CO2H
H
H
0.41
0.41
0.5
0.57
1:1 (200)
1:1 (200)
9:1 (100)
1:1 (200)
1:1 (300)
4:1 (50)
31
23
26
24
35
24
16
24
21
24
33 (3b)
33 (1a)
b
—
67 (3o)
—
89 (1a)
25 (1f)
90 (1f)
27 (1a)
n.d.c (1a)
—
—
CO2H
Bn
Bn
H
1.0
b
CO2H
0.5
—
CH(OH)Me
CH(OH)Me
CHO
0.5
1.2
43 (3b)
—
b
H
0.21
0.38
0.19
0.32
0.29
—
H
1.1
4:1 (300)
4:1 (50)
100
100
100
71
80 (3b)
—
b
CHO
H
96 (1a)
—
—
CH(CO2Me)2
CH(CO2Me)2
H
1.1
4:1 (300)
4:1 (50)
93 (3b)
—
b
H
45 (1a)
—
a Determined by 1H NMR spectroscopy of the crude product. b In the absence of potassium propionate (2b). c Not determined.
Likewise N-phthaloyl-β-alanine (6) and potassium propionate (2b) gave a mixture of the intramolecular
cyclization/ring-expansion product (7) and the β-decarboxylation/alkylation product (3p) in isolated
yields of 28% and 43%, respectively (Scheme 5). Since solely the potassium salt of 6 is known to under-
go decarboxylation upon irradiation in aqueous acetone,8,14 rapid K/H-exchange obviously precedes

product formation. Compound (3p) is formed via photoinduced alkylation of the simple β-decarboxy-
lation intermediate of 6.
O
O
HO
CO H
2
hν
N
CO K
N
+
+
2
acetone / water
NH
O
O
O
3p (43%)
6
2b
7 (28%)
Scheme 5
A special case was the irradiation of 1a in the presence of sodium formate (8). Although we have pre-
viously reported the formation of the corresponding hydroxyphthalimidine (9) in 62% yield,9 2-methyl-
2,3-dihydroisoindol-1-one (10) was formed instead when the original experiment was repeated. During
consequent reexamination of this reaction, we noticed that the outcome of the photolysis was, however,
sensitive to the reaction conditions applied (Scheme 6; Table 3). Irradiations in aqueous acetone mainly
gave the reduction product (10) in amounts of 75-85%. Besides, smaller amounts of the hydroxy-
phthalimidine (9; up to 8%) and the diol (11; 5-25%) were identified, the latter generated via trapping of
the solvent acetone. In contrast, when the experiments were undertaken in aqueous acetonitrile, 3-
hydroxy-2-methyl-2,3-dihydroisoindol-1-one (9) became the dominant product (62-67%), and next to 10
(5-18%) the C=C reduction product (12) was obtained in amounts of 20-27%. The assumed structure of
12 was supported by NMR and MS spectroscopic analysis, although the mechanism of its formation re-
mains unclear at present.
HO
H
H
H
N
Me
N Me
+
+
O
O
O
9
10
hν
N
Me
HCO Na
+
2
OH
OH
solvent / water
O
HO
O
N
Me
N Me
+
1a
8
O
O
11
12
Scheme 6
The solvent dependence of the chemoselectivity was striking, but when the primary photoreduction prod-
uct (9) was finally irradiated in aqueous acetone and in the presence of 8 it was readily converted into 2-
methyl-2,3-dihydroisoindol-1-one (10). Hence, irradiation of 1a in the presence of formate is dominated

by stepwise photoreduction and photo-dearomatization, and both pathways have been described in the
photochemistry of phthalimides.7b,15 In addition, similar phenomena have been reported by Kubo and
coworkers for irradiations of other imide chromophores in the presence of secondary amines.16
Table 3 Experimental details and product composition of photoreactions involving 8.
Product quantity and compositiona
Substrates
Conditions
solvent/ time amount
1a
8
solvent
9 [%]
10 [%] 11 [%] 12 [%]
amount [g]
amount [g]
H2O [mL] [h]
[mg]
219b
253b
95c
0.33
0.79
1.35
0.68
1.35
acetone 4:1 (300)
acetone 1:1 (300)
MeCN 1:1 (200)
MeCN 1:1 (300)
23
20
22
20
trace
8
75
87
6
25
5
—
—
27
20
0.32
0.32
67
—
—
0.32
125
62
18
a Determined by 1H NMR analysis of the crude product (± 5%). b Significant amounts of 4-hydroxy-4-methyl-2-pentanone
(13) and of polymeric byproducts. c Conversion ca. 85%.
As a conclusion the photoinduced decarboxylative addition of potassium carboxylates to phthalimides
represents a useful methodology for the synthesis of alkylated hydroxyphthalimidines. The mild condi-
tions and the easy availability (commercially or synthetically) of all starting materials make this pro-
cedure a versatile alternative to existing thermal reactions and furthermore suitable for green photo-
chemistry.17
EXPERIMENTAL
Melting points were measured on a Büchi B-535 apparatus and are uncorrected. 1H and 13C NMR spectra
were recorded on a Bruker DPX 300 or Bruker AC 300 F spectrometer (300 MHz and 75.5 MHz, re-
spectively) using the solvent residual peak as internal standard. Chemical shifts (δ) are given in ppm,
coupling constants (J) in Hz. MS spectra were recorded on a Finnigan Incos 500 (CI or EI), HRMS on a
Finnigan MAT H-SQ 30 (FAB) spectrometer. IR spectra were recorded on a Perkin-Elmer FT-IR-S 1600
FT/IR spectrophotometer, UV/VIS spectra on a Perkin-Elmer Lambda 7 spectrophotometer using aceto-
nitrile (Merck, puriss. p.a.) as solvent. For combustion analysis an Elementar Vario EL was used. A
Rayonet© RPR-208 chamber photoreactor (8 × 3000 Å lamps, ca. 800 W, λ = 300 ± 10 nm), high-pres-
sure mercury lamp (400 W) or Heraeus Nobelight XeCl excimer lamp (3 kW, λ = 308 nm) and immer-
sion wall reactors (λ > 280 nm) were used for irradiation experiments. X-Ray structure analysis was per-
formed on an Enraf-Nonius CAD4 diffractometer. TLC was carried out on Merck Kieselgel 60 F254,
column chromatography on silica gel (Macherey & Nagel) 230-240 mesh using mixtures of ethyl acetate

(EA) and n-hexane (Hex). Solvents and reagents were commercially available and were used without
further purification. The phthalimide derivatives were prepared via literature procedures: 1a,18a 1b,18b
1c,18c 1d,18d,e 1e,18d,e 5a,18d 5b,18f 5c,18g 5d18h and 5e,18h,i respectively.
General procedure for the photoreactions: The phthalimide (2 mmol) was dissolved in acetone (240
mL). A solution of potassium carboxylate (5 mmol) in water (60 mL) was added, and the mixture was
irradiated at 15-20°C in a Pyrex tube while purging with a slow stream of N2. The progress of the reac-
tion was followed by TLC analysis. The solution was extracted with CH2Cl2 (3 × 100 mL), washed with
5% NaHCO3 and brine, dried (MgSO4), and concentrated to dryness. The products were obtained after
column chromatography or recrystallization. Experimental details are given in Table 1.
2,3-Dimethyl-3-hydroxy-2,3-dihydroisoindol-1-one (3a). After column chromatography (SiO2,
EA/Hex: 2:1). 138 mg (39%) of 3a as a slightly beige solid. The conversion was determined by 1H NMR
1
spectroscopic analysis of the crude product as 42%; mp: 125-127°C (lit.,19 128-130°C). H NMR
(CDCl3): δ 1.59 (s, 3H, CH3), 2.72 (s, 3H, NCH3), 4.07 (br s, 1H, OH), 7.32 (ddd, J = 1.6, 6.8, 7.6, 1H,
Harom), 7.41 (d, J = 7.6, 1H, Harom), 7.51 (ddd, J = 1.2, 6.8, 7.6, 1H, Harom), 7.55 (dd, J = 1.6, 6.8, 1H,
13
Harom). C NMR (CDCl3): δ 23.1 (CH3), 23.3 (NCH3), 88.2 (COH), 121.6 (CH), 123.0 (CH), 129.2
(CH), 130.2 (Cq), 132.2 (CH), 148.2 (Cq), 166.8 (CON). MS (EI, 70 eV): m/z (%) 160 (11), 159 (M+-
H2O, 100), 131 (17), 130 (91), 116 (13), 103 (17), 90 (15), 76 (17), 54 (18). IR (KBr disc): ν (cm-1) 3410,
2934, 1774, 1680, 1431, 1139, 1082, 764, 696. Anal. Calcd for C10H11NO2: C 67.78, H 6.26, N 7.90.
Found: C 67.98, H 6.18, N 7.93.
3-Ethyl-3-hydroxy-2-methyl-2,3-dihydroisoindol-1-one (3b). After recrystallization from toluene/n-
1
hexane. 374 mg (88%) of 3b as colorless crystals; mp: 140-143°C (lit.,10b 141-142°C). H NMR (ace-
tone-d6): δ 0.43 (t, J = 7.4, 3H, CH3), 2.07 (qd, J = 7.4, 14.3, 1H, CH2), 2.18 (qd, J = 7.4, 14.3, 1H, CH2),
2.87 (s, 3H, NCH3), 5.48 (s, 1H, OH), 7.48 (m, 1H, Harom), 7.60 (m, 3H, Harom). 13C NMR (acetone-d6): δ
7.9 (CH3), 23.1 (NCH3), 29.2 (CH2), 91.5 (COH), 122.6 (CH), 123.0 (CH), 129.7 (CH), 132.6 (CH),
132.8 (Cq), 147.8 (Cq), 167.2 (CON). MS (EI, 70 eV): m/z (%) 173 (M+-H2O, 97), 162 (100), 158 (37),
144 (30), 130 (29), 117 (30), 76 (27), 50 (15). IR (CsI disc): ν (cm-1) 3285, 1700, 1684, 1431, 1399,
1095. UV/VIS (CH3CN): λmax (ε) 249.2 (2989), 217.0 (9612) nm. Anal. Calcd for C11H13NO2: C 69.09,
H 6.85, N 7.32. Found: C 68.33, H 7.11, N 7.24.
3-Hydroxy-3-isopropyl-2-methyl-2,3-dihydroisoindol-1-one (3c). Run A (Rayonet): after work-up.
308 mg (86%) of 3c. Run B (Excimer): after recrystallization from acetone. 5.13 g (63%) of 3c as a
colorless solid. The conversion was determined by GC analysis of the crude product as 73%; mp: 145-
1
147°C (lit.,10b 148-149°C). H NMR (acetone-d6): δ 0.41 (d, J = 6.8, 3H, CH3), 1.12 (d, J = 6.8, 3H,
CH3), 2.35 (sept, J = 6.8, 1H, CH), 2.81 (s, 3H, NCH3), 5.32 (s, 1H, OH), 7.41 (ddd, J = 1.5, 6.8, 7.3, 1H,

13
Harom), 7.47-7.56 (m, 3H, Harom). C NMR (acetone-d6): δ 16.7 (CH3), 17.4 (CH3), 23.6 (NCH3), 34.6
(CH), 93.2 (COH), 123.0 (CH), 124.1 (CH), 129.8 (CH), 132.0 (CH), 133.5 (Cq), 146.6 (Cq), 166.9
(CON). MS (EI, 70 eV): m/z (%) 187 (M+-H2O, 14), 172 (22), 162 (100), 133 (17), 105 (8), 77 (19), 50
(17). IR (CsI disc): ν (cm-1) 3271, 2977, 1681, 1677, 1481, 1430, 1368, 1097, 772. Anal. Calcd for
C12H15NO2: C 70.22, H 7.37, N 6.82. Found: C 69.83, H 7.62, N 6.94.
3-sec-Butyl-3-hydroxy-2-methyl-2,3-dihydroisoindol-1-one (3d). After column chromatography (SiO2,
EA/Hex: 1:1). 386 mg (89%) of 3d as a colorless solid. The diastereoisomes were assigned as reported
earlier,20 and the diastereoisomeric ratio was determined by 1H NMR spectroscopic analysis of the crude
product as 55:45 (u-3d : l-3d); Rf (mixture) = 0.29 (EA/Hex: 1:1); mp (mixture): 102-105°C. Main u-dia-
1
stereoisomer (u-3d). H NMR (CDCl3): δ 0.35 (d, J = 6.9, 3H, CH3), 0.79-1.22 (m, 2H, CH, CH2), 0.93
(t, J = 7.4, 3H, CH3), 1.94 (m, 1H, CH2), 2.55 (s, 3H, NCH3), 4.84 (br s, 1H, OH), 7.28 (m, 1H, Harom),
7.36-7.51 (br m, 3H, Harom). 13C NMR (CDCl3): δ 12.6 (CH3), 12.8 (CH3), 23.2 (CH2), 23.8 (NCH3), 40.9
(CH), 93.0 (COH), 122.6 (CH), 123.1 (CH), 128.9 (CH), 131.3 (Cq), 131.4 (CH), 145.5 (Cq), 167.3
(CO2). Minor l-diastereoisomer (l-3d). 1H NMR (CDCl3): δ 0.26 (m, 1H, CH), 0.71 (t, J = 7.4, 3H, CH3),
0.79-1.22 (m, 1H, CH2), 1.12 (d, J = 6.9, 3H, CH3), 2.10 (m, 1H, CH2), 2.55 (s, 3H, NCH3), 4.84 (br s,
1H, OH), 7.28 (m, 1H, Harom), 7.36-7.51 (br m, 3H, Harom). 13C NMR (CDCl3): δ 11.7 (CH3), 13.3 (CH3),
23.0 (CH2), 23.4 (NCH3), 40.4 (CH), 92.8 (COH), 122.7 (CH), 122.9 (CH), 128.9 (CH), 131.4 (CH),
131.7 (Cq), 145.9 (Cq), 167.4 (CO2). MS (FAB, 70 eV, mixture): m/z (%) 202 (M+-H2O, 100), 174 (11),
162 (10), 147 (16), 105 (8). IR (CsI disc, mixture): ν (cm-1) 3279, 2964, 1700, 1684, 1675, 1480, 1073,
775, 703. UV/VIS (CH3CN, mixture): λmax (ε) 247.4 (3141) nm. HRMS (PI-FAB, mixture): Anal. Calcd
for C13H17NO2: 220.134. Found: 220.132 ± 0.002.
3-Hydroxy-3-isobutyl-2-methyl-2,3-dihydroisoindol-1-one (3e). After column chromatography (SiO2,
1
EA/Hex: 1:1). 220 mg (51%) of 3e as a colorless, waxy solid. The conversion was determined by H
1
NMR spectroscopic analysis of the crude product as 85%; Rf = 0.43 (EA/Hex: 1:1); mp: 79-83°C. H
NMR (CDCl3): δ 0.42 (d, J = 7.0, 3H, CH3), 0.74 (d, J = 7.0, 3H, CH3), 1.02 (m, 1H, CH), 2.01 (m, 2H,
CH2), 2.75 (s, 3H, NCH3), 3.88 (s, 1H, OH), 7.27-7.56 (m, 4H, Harom). 13C NMR (CDCl3): δ 22.9 (CH3),
23.3 (NCH3), 24.7 (Cq), 43.5 (CH2), 90.6 (COH), 122.7 (CH), 123.4 (CH), 130.0 (CH), 131.4 (Cq),
132.3 (CH), 147.7 (Cq), 168.5 (CON). IR (CsI disc): ν (cm-1) 3298, 2924, 1673, 1430, 769, 704. HRMS
(PI-FAB): Anal. Calcd for C13H17NO2: 220.134. Found: 220.133 ± 0.002.
3-tert-Butyl-3-hydroxy-2-methyl-2,3-dihydroisoindol-1-one (3f). Run A (Rayonet): after column
chromatography (SiO2, EA/Hex: 3:1). 247 mg (57%) of 3f as a colorless solid. Run B (HP mercury
lamp): after recrystallization from acetone. 330 mg (76%) of 3f as a colorless solid. The conversion was
1
1
determined by H NMR spectroscopic analysis of the crude product as 89%; mp: 167-169°C. H NMR

(CDCl3): δ 0.97 (s, 9H, CH3), 2.80 (s, 3H, NCH3), 3.74 (s, 1H, OH), 7.35 (ddd, J = 1.2, 7.5, 7.5, 1H,
13
Harom), 7.43 (ddd, J = 1.2, 7.5, 7.5, 1H, Harom), 7.56 (d, J = 7.5, 2H, Harom). C NMR (CDCl3): δ 26.1
(CH3), 27.4 (NCH3), 39.5 (Cq), 94.9 (COH), 122.8 (CH), 123.9 (CH), 129.1 (CH), 130.9 (CH), 132.1
(Cq), 147.3 (Cq), 168.0 (CON). MS (EI, 70 eV): m/z (%) 204 (M+-CH3, 8), 202 (7), 189 (10), 164 (100),
133 (10), 117 (4), 105 (7), 91 (4), 77 (7), 56 (14). IR (CsI disc): ν (cm-1) 3278, 2967, 1665, 1613, 1427,
1392, 1071, 766, 708. HRMS (PI-FAB): Anal. Calcd for C13H17NO2: 220.134. Found: 220.130 ± 0.004.
3-(2,2-Dimethylpropyl)-3-hydroxy-2-methyl-2,3-dihydroisoindol-1-one (3g). After column chroma-
tography (SiO2, EA/Hex: 1:1). 252 mg (80%) of 3g as a yellowish oil; Rf = 0.36 (EA/Hex: 1:1). 1H NMR
(acetone-d6): δ 0.51 (s, 9H, CH3), 2.13 (s, 2H, CH2), 2.81 (s, 3H, NCH3), 5.11 (s, 1H, OH), 7.39 (ddd, J =
13
0.9, 7.3, 7.5, 1H, Harom), 7.49 (ddd, J = 0.9, 7.3, 7.5, 1H, Harom), 7.52-7.57 (m, 2H, Harom). C NMR
(acetone-d6): δ 24.2 (NCH3), 30.3 (Cq), 30.7 (CH3), 47.6 (CH2), 90.1 (COH), 123.2 (CH), 124.1 (CH),
129.8 (CH), 132.1 (CH), 132.4 (Cq), 149.2 (Cq), 167.3 (CON). MS (EI, 70 eV): m/z (%) 218 (M+-CH3,
4), 200 (44), 192 (3), 162 (36), 146 (100), 132 (8), 117 (17), 91 (11), 77 (17), 56 (21), 55 (20), 50 (16).
IR (film): ν (cm-1) 3361, 2954, 1682, 1434, 1397, 1055, 772, 704. HRMS (PI-FAB): Anal. Calcd for
C14H19NO2: 234.149. Found: 234.147 ± 0.002.
3-Benzyl-3-hydroxy-2-methyl-2,3-dihydroisoindol-1-one (3h). After recrystallization from acetone.
1
485 mg (88%) of 3h as colorless crystals; mp: 164-168°C (lit.,10c 165-168°C). H NMR (acetone-d6): δ
2.97 (s, 3H, NCH3), 3.23 (d, J = 13.8, 1H, CH2Ph), 3.42 (d, J = 13.8, 1H, CH2Ph), 5.27 (s, 1H, OH), 6.83
13
(m, 2H, Harom), 6.98 (m, 3H, Harom), 7.28-7.37 (m, 2H, Harom), 7.45 (m, 2H, Harom). C NMR (acetone-
d6): δ 23.9 (NCH3), 43.0 (CH2Ph), 91.1 (COH), 122.9 (CH), 123.7 (CH), 127.3 (CH), 128.5 (CH), 129.8
(CH), 130.8 (CH), 132.1 (CH), 133.0 (Cq), 136.3 (Cq), 147.9 (Cq), 166.8 (CON). MS (EI, 70 eV): m/z
(%) 207 (1), 189 (45), 174 (44), 162 (100), 133 (24), 117 (19), 91 (20), 77 (22), 51 (4). IR (CsI disc): ν
(cm-1) 3283, 1684, 1428, 1404, 1073, 774, 759, 703, 606. UV/VIS (CH3CN): λmax (ε) 228.2 (7373),
255.4 (3226) nm. Anal. Calcd for C16H15NO2: C 75.87, H 5.96, N 5.52. Found: C 75.70, H 6.01, N 5.44.
Crystal data for 3h: M = 253.29; monoclinic, space-group P 21/c; a = 9.670(1), b = 9.315(1), c =
14.886(1) Å; β = 98.93(1)°; V = 1324.6(2) Å3; Z = 4; dcalc = 1.27 g/cm3; unique reflections: 2878; reflec-
tions I > 2σ(I): 2042; R1, wR2: 0.043, 0.104. The crystallographic data has been deposited with
Cambridge Crystallographic Data Center as supplementary publication no. CCDC-194007.
Irradiation of N-methylphthalimide (1a) in the presence of potassium benzoate (2i). After work-up.
301 mg (86%) of reisolated 1a.
3-Ethyl-3-hydroxy-2-phenyl-2,3-dihydroisoindol-1-one (3j). After recrystallization from acetone. 277
mg (55%) of 3j as a colorless solid. The conversion was determined by 1H NMR spectroscopic analysis of
1
the crude product as 60%; mp: 160-163°C (lit.,10b 159-160°C). H NMR (CDCl3): δ 0.37 (t, J = 7.5,

3H, CH3), 1.89 (qd, J = 7.5, 14.3, 1H, CH2), 2.01 (qd, J = 7.5, 14.3, 1H, CH2), 3.99 (s, 1H, OH), 7.15-
7.33 (m, 4H, Harom), 7.43-7.51 (m, 5H, Harom). 13C NMR (CDCl3): δ 7.7 (CH3), 28.7 (CH2), 93.9 (COH),
121.7 (CH), 123.6 (CH), 126.2 (CH), 126.7 (CH), 128.8 (CH), 129.6 (CH), 131.0 (Cq), 132.8 (CH),
135.5 (Cq), 146.0 (Cq), 167.0 (CON). MS (EI, 70 eV): m/z (%) 236 (17), 235 (M+-H2O, 100), 220 (96),
206 (22), 191 (5), 178 (9), 165 (10), 152 (7), 130 (20), 115 (16), 102 (21), 77 (58), 63 (7), 50 (11). Anal.
Calcd for C16H15NO2: C 75.87, H 5.97, N 5.53. Found: C 76.01, H 6.02, N 5.33.
3-Ethyl-3-hydroxy-2-prop-2-ynyl-2,3-dihydroisoindol-1-one (3k). After work-up. 189 mg (0.88
mmol, 88%) of 3k as a yellowish oil. 1H NMR (CDCl3): δ 0.52 (t, J = 7.4, 3H, CH3), 1.98-2.33 (m, 3H,
CH2, CH), 4.08 (d, J = 2.5, 1H, NCH2), 7.40 (ddd, J = 1.0, 7.4, 7.4, 1H, Harom), 7.47 (d, J = 7.4, 1H,
13
Harom), 7.53 (ddd, J = 1.0, 7.4, 7.4, 1H, Harom), 7.64 (d, J = 7.4, 1H, Harom). C NMR (CDCl3): δ 8.0
(CH3), 26.7 (NCH2), 29.1 (CH2), 70.6 (≡CH), 78.9 (C≡), 91.9 (COH), 121.7 (CH), 123.3 (CH), 129.4
(CH), 130.9 (Cq), 132.5 (CH), 146.5 (Cq), 166.9 (CON). HRMS (PI-FAB): Anal. Calcd for C13H13NO2:
216.102. Found: 216.104 ± 0.003.
(1-Ethyl-1-hydroxy-3-oxo-1,3-dihydroisoindol-2-yl)acetic acid methyl ester (3l). After recrystalliza-
tion from acetone. 332 mg (88%) of 3l as colorless crystals; mp: 108-110°C. 1H NMR (CDCl3): δ 0.47 (t,
J = 7.5, 3H, CH3), 1.92 (qd, J = 7.5, 14.6, 1H, CH2), 2.08 (qd, J = 7.5, 14.6, 1H, CH2), 3.66 (s, 3H,
OCH3), 3.79 (d, J = 17.6, 1H, NCH2), 4.04 (br s, 1H, OH), 4.34 (d, J = 17.6, 1H, NCH2), 7.40 (ddd, J =
1.0, 7.5, 7.5, 1H, Harom), 7.44 (dd, J = 1.0, 7.5, 1H, Harom), 7.51 (ddd, J = 1.0, 7.5, 7.5, 1H, Harom), 7.66
13
(dd, J = 1.0, 7.5, 1H, Harom). C NMR (CDCl3): δ 7.5 (CH3), 28.7 (NCH2), 39.5 (CH2), 52.4 (OCH3),
91.3 (COH), 121.8 (CH), 123.3 (CH), 129.4 (CH), 130.6 (Cq), 132.5 (CH), 146.7 (Cq), 167.6 (CON),
170.5 (CO2). IR (CsI disc): ν (cm-1) 3298, 1739, 1679, 1426, 1268. Anal. Calcd for C13H15NO4: C 62.64,
H 6.07, N 5.62. Found: C 62.91, H 6.23, N 5.48. Crystal data for 3l: M = 249.26; triclinic, space-group P
1; a = 7.907(1), b = 8.245(1), c = 10.717(1) Å; α = 113.75(1), β = 95.04(1), γ = 97.01(1)°; V =
627.47(12) Å3; Z = 2; dcalc = 1.319 g/cm3; unique reflections: 2426; reflections I > 2σ(I): 1539; R1, wR2:
0.049, 0.114. The crystallographic data has been deposited with Cambridge Crystallographic Data Center
as supplementary publication no. CCDC-194006.
[2-(1-Ethyl-1-hydroxy-3-oxo-1,3-dihydroisoindol-2-yl)acetylamino]acetic acid methyl ester (3m).
1
After column chromatography (SiO2, EA/Hex: 3:1). 297 mg (52%) of 3m as a colorless oil. H NMR
(CDCl3): δ 0.48 (t, J = 7.5, 3H, CH3), 2.06 (qd, J = 7.5, 14.6, 1H, CH2), 2.19 (qd, J = 7.5, 14.6, 1H, CH2),
3.65 (s, 3H, OCH3), 3.84 (d, J = 16.3, 1H, NCH2), 3.89 (dd, J = 5.7, 18.1, 1H, CH2CO2), 4.05 (dd, J =
5.7, 18.1, 1H, CH2CO2), 4.45 (d, J = 16.3, 1H, NCH2), 4.97 (br s, 1H, OH), 7.16 (t, J = 5.7, 1H, NH),
7.16 (ddd, J = 1.1, 7.2, 7.4, 1H, Harom), 7.51 (d, J = 7.2, 1H, Harom), 7.57 (dd, J = 7.2, 7.4, 1H, Harom), 7.71
13
(d, J = 7.4, 1H, Harom). C NMR (CDCl3): δ 7.7 (CH3), 29.1 (NHCH2), 41.2 (CH2), 42.2 (NCH2), 52.4

(OCH3), 91.8 (COH), 122.0 (CH), 123.4 (CH), 129.5 (CH), 130.4 (Cq), 132.9 (CH), 147.1 (Cq), 168.4
(CON), 170.0 (CONH), 170.5 (CO2). Anal. Calcd for C15H18N2O5: C 58.82, H 5.92, N 9.15. Found: C
58.88, H 6.03, N 9.01.
3-Adamant-1-yl-3-hydroxy-2-methyl-2,3-dihydroisoindol-1-one (3n). Run A (Rayonet): a suspension
of 322 mg (2.0 mmol) of N-methyl phthalimide (1a) and 4.37 g (20.0 mmol) of potassium adamantanate
(2j) in 200 mL of water/acetone (3:97) was irradiated for 106 h. The reaction mixture was evaporated to
dryness and the crude product was extracted in a Soxhlet-apparatus with pentane. 1.86 g (69%) of ada-
mantane (4) were obtained as a colorless solid. Inspection of the crude product by 1H NMR spectroscopic
and TLC analysis showed that most of 1a remained unchanged. Run B (HP mercury lamp): a clear solu-
tion of 320 mg (1.99 mmol) of N-methyl phthalimide (1a) and 2.18 g (10.0 mmol) of potassium ada-
mantanate (2j) in 300 mL of water/acetone (1:1) was irradiated for 3 h. A colorless precipitation occurred
which was dissolved in hexane. The reaction mixture was furthermore extracted twice with hexane, the
combined hexane layers were dried over MgSO4 and evaporated giving 810 mg (60%) of 4 as a colorless
solid. Adamantane (4). mp: 211-214°C (lit.,21 212-215°C). 1H NMR (CDCl3): δ 1.73 (br s, 12H, CH2),
1.85 (br s, 4H, CH). 13C NMR (CDCl3): δ 28.3 (CH), 37.8 (CH2). MS (EI, 70 eV): m/z (%) 136 (M+,
100), 121 (11), 107 (12), 93 (64), 91 (20), 79 (85), 77 (32), 67 (45), 65 (15), 53 (26), 51 (11), 43 (10), 41
(57). IR (KBr disc): ν (cm-1) 2924, 2899, 2846, 1450, 1352, 1101, 798. The acetone/water layer was
1
treated as described in the general procedure. Drying in vacuo gave 295 mg of a yellowish solid. H
NMR spectroscopic and TLC analysis showed that most of the starting material 1a remained unchanged.
Column chromatography (SiO2, EA/Hex: 1:1) gave 250 mg (78%) of reisolated 1a and 12 mg (2%) of 3n
as a colorless solid. 3-Adamant-1-yl-3-hydroxy-2-methyl-2,3-dihydroisoindol-1-one (3n). Rf = 0.48
(EA/Hex: 1:1); mp: 198-205°C. 1H NMR (CDCl3): δ 1.45-1.75 (br m, 9H, CH, CH2), 1.85-2.00 (m, 6H,
CH2), 2.56 (s, 1H, OH), 3.06 (s, 3H, NCH3), 7.40-7.50 (m, 2H, Harom), 7.57 (m, 1H, Harom), 7.73 (m, 1H,
13
Harom). C NMR (CDCl3): δ 28.3 (CH), 28.5 (NCH3), 36.6 (CH2), 36.9 (CH2), 41.5 (Cq), 95.2 (COH),
122.9 (CH), 124.2 (CH), 129.3 (CH), 130.7 (CH), 132.5 (Cq), 146.8 (Cq), 168.2 (CON). HRMS (PI-
FAB): Anal. Calcd for C19H24NO2: 298.181. Found: 298.184 ± 0.004. The aqueous layer obtained during
work-up was acidified with 2M hydrochloric acid upon which a colorless solid precipitated. Filtration,
washing with water and drying in vacuo gave 670 mg (37%) of reisolated 1-adamantanecarboxylic acid.
Irradiation of phthalimides (5a, c-e) in the presence of potassium propionate (2b). Following the
above procedure, irradiations of N-substituted phthalimides (5a, c-e) and potassium propionate in
water/acetone mixtures gave mixtures of 3b and N-methylphthalimide (1a). The product ratios (3b:1a)
1
were determined by H NMR spectroscopic analysis of the crude product. For experimental details and
results, see Table 2.

3-Ethyl-3-hydroxy-2-phenylethyl-2,3-dihydroisoindol-1-one (3o). After column chromatography
(SiO2, EA/Hex: 3:1). 316 mg (67%) of 3o as a colorless solid; mp: 130-133°C. 1H NMR (CDCl3): δ 0.41
(t, J = 7.5, 3H, CH3), 2.00 (qd, J = 7.5, 14.4, 1H, CH2), 2.12 (qd, J = 7.5, 14.4, 1H, CH2), 2.85 (ddd, J =
5.3, 10.6, 12.9, 1H, CH2Ph), 3.01 (ddd, J = 5.8, 10.6, 12.9, 1H, CH2Ph), 3.19 (ddd, J = 5.8, 10.6, 13.7,
1H, NCH2), 3.64 (ddd, J = 5.3, 10.6, 13.7, 1H, NCH2), 3.73 (br s, 1H, OH), 7.13-7.24 (br m, 5H, Harom),
7.29 (ddd, J = 1.5, 7.1, 7.5, 1H, Harom), 7.39 (d, J = 7.5, 1H, Harom), 7.43 (ddd, J = 1.0, 7.1, 7.5, 1H,
13
Harom), 7.50 (d, J = 7.5, 1H, Harom). C NMR (CDCl3): δ 7.7 (CH3), 29.0 (CH2), 34.8 (NCH2), 40.4
(CH2), 91.9 (COH), 121.6 (CH), 122.9 (CH), 126.3 (CH), 128.4 (CH), 128.8 (CH), 129.3 (CH), 131.3
(Cq), 132.1 (CH), 139.2 (Cq), 146.4 (Cq), 167.6 (CON). MS (FAB, 70 eV): m/z (%) 282 (M+1, 79), 264
(48), 220 (50), 185 (75), 161 (100), 147 (40), 105 (58). IR (CsI disc): ν (cm-1) 3265, 1734, 1700, 1684,
1473, 1419, 1091, 760, 699. UV/VIS (CH3CN): λmax (ε) 250.0 (3928) nm. HRMS (PI-FAB): Anal. Calcd
for C18H19NO2: 282.149. Found: 282.153 ± 0.004. N-2-Phenylethylphthalimide (1f). As second frac-
tion, 107 mg (25%) of 1f were obtained as a colorless oil. 1H NMR (acetone-d6): δ 3.36-3.49 (t, J = 7.5,
13
2H, CH2Ph), 3.85 (t, J = 7.5, 2H, NCH2), 7.20-7.29 (m, 5H, Harom), 7.77 (br s, 4H, Harom). C NMR
(acetone-d6): δ 34.9 (CH2Ph), 39.7 (NCH2), 123.6 (CH), 127.2 (Cq), 129.1 (CH), 129.5 (CH), 130.9
(Cq), 132.9 (CH), 168.5 (CON). The product ratio was determined by 1H NMR spectroscopic analysis of
the crude product as 2.6:1.0 (3o:1f).
3-Hydroxy-2,3-diethyl-2,3-dihydroisoindol-1-one (3p). Following the above procedure, irradiation of
420 mg (1.92 mmol) of N-phthaloyl-β-alanine (6) and 1.13 g (10.0 mmol) of potassium propionate in
300 mL of water/acetone (1:4) for 27 h gave, after column chromatography (SiO2, EA/Hex: 2:1), 168 mg
(43%) of 3p as a colorless oil; Rf = 0.20 (EA/Hex: 2:1). 1H NMR (CDCl3): δ 0.45 (t, J = 7.2, 3H, CH3),
1.18 (t, J = 7.2, 3H, CH3), 2.02 (qd, J = 7.2, 14.5, 1H, CH2), 2.15 (qd, J = 7.2, 14.5, 1H, CH2), 3.13 (qd, J
= 7.2, 14.5, 1H, NCH2), 3.43 (qd, J = 7.2, 14.5, 1H, NCH2), 3.80 (br s, 1H, OH), 7.35 (dd, J = 7.3, 7.3,
13
1H, Harom), 7.42-7.52 (m, 3H, Harom). C NMR (CDCl3): δ 7.8 (CH3), 14.3 (CH3), 28.9 (NCH2), 33.1
(CH2), 92.1 (COH), 121.5 (CH), 122.9 (CH), 129.3 (CH), 131.5 (Cq), 132.0 (CH), 146.4 (Cq), 167.4
(CON). HRMS (PI-FAB): Anal. Calcd for C12H15NO2: 206.118. Found: 206.120 ± 0.002. 2,3,4,5-Tetra-
hydro-1H-2-benzazepin-1,5-dione (7). As second fraction, 93 mg (28%) of 7 were obtained as a color-
1
less solid; mp: 163-165°C (lit.,22 161-162°C). H NMR (CDCl3): δ 2.86 (t, J = 6.8, 2H, CH2CO), 3.43
(m, 2H, CH2NH), 7.27-7.80 (m, 5H, NH, Harom). 13C NMR (CDCl3): δ 37.2 (CH2), 46.1 (CH2NH), 128.5
(CH), 130.2 (CH), 132.0 (CH), 132.1 (Cq), 132.8 (CH), 136.0 (Cq), 171.1 (CONH), 202.1 (CO). Anal.
Calcd for C10H9NO2: C 68.56, H 5.18, N 8.00. Found: C 68.71, H 5.23, N 7.86. The product ratio was
determined by 1H NMR spectroscopic analysis of the crude product as 57:43 (3p:7).

Irradiations of N-methylphthalimide (1a) in the presence of sodium formate (8). Following the
above procedure, 1a was irradiated in the presence of 8 in water/acetone or water/acetonitrile mixtures,
respectively. The product ratios and compositions were determined by 1H NMR spectroscopic analysis of
the crude product. Small amounts of the reaction products were isolated and purified for analysis. For
experimental details and results, see Table 3. 3-Hydroxy-2-methyl-2,3-dihydroisoindol-1-one (9). mp:
1
127-129°C (lit.,23 128-129°C). H NMR (CDCl3): δ 2.83 (s, 3H, NCH3), 4.26 (br d, J = 10.3, 1H, OH),
5.53 (d, J = 10.3, 1H, CHN), 7.32 (dd, J = 7.4, 7.4, 1H, Harom), 7.40 (d, J = 7.4, 1H, Harom), 7.47 (dd, J =
13
7.4, 7.4, 1H, Harom), 7.52 (d, J = 7.4, 1H, Harom). C NMR (CDCl3): δ 26.0 (NCH3), 83.5 (CHN), 122.9
(CH), 123.2 (CH), 129.5 (CH), 131.2 (Cq), 132.1 (CH), 143.8 (Cq), 167.6 (CON). MS (EI, 70 eV): m/z
(%) 163 (M+, 72), 162 (100), 146 (60), 133 (37), 105 (57), 91 (19), 77 (49), 50 (29). IR (CsI disc): ν
(cm-1) 3287, 1687, 1682, 1673, 1481, 1439, 1056, 750. UV/VIS (CH3CN): λmax (ε) 246.4 (3227), 227.0
(6550), 218.6 (9285), 207.4 (3495) nm. Anal. Calcd for C9H9NO2: C 66.25, H 5.56, N 8.58. Found: C
65.96, H 5.81, N 8.37. 2-Methyl-2,3-dihydroisoindol-1-one (10). mp: 115-117°C (lit.,24 115-116°C). 1H
NMR (CDCl3): δ 3.17 (s, 3H, NCH3), 4.35 (s, 2H, CH2N), 7.40 (dd, J = 1.0, 7.2, 1H, Harom), 7.43 (d, J =
7.2, 1H, Harom), 7.50 (dd, J = 1.0, 7.2, 1H, Harom), 7.80 (d, J = 7.2, 1H, Harom). 13C NMR (CDCl3): δ 29.4
(NCH3), 51.9 (CH2N), 122.5 (CH), 123.6 (CH), 128.0 (Cq, CH), 131.1 (CH), 140.9 (Cq), 168.6 (CON).
MS (EI, 70 eV): m/z (%) 147 (M+, 100), 128 (10), 118 (75), 91 (32), 77 (15), 51 (10). IR (KBr disc): ν
(cm-1) 1672, 1615, 1481, 1445, 1421, 1056, 745. Anal. Calcd for C9H9NO: C 73.45, H 6.16, N 9.52.
Found: C 73.53, H 6.04, N 9.54. 3-Hydroxy-3-(1-hydroxy-1-methylethyl)-2-methyl-2,3-dihydroisoin-
1
dol-1-one (11). Rf = 0.28 (EA/Hex: 2:1); mp: 164-166°C. H NMR (CDCl3, 10% DMSO-d6): δ 0.88 (s,
3H, CH3), 1.21 (s, 3H, CH3), 2.99 (s, 3H, NCH3), 3.39 (s, 1H, OH), 5.89 (s, 1H, OH), 7.32 (ddd, J = 1.2,
6.8, 7.4, 1H, Harom), 7.38 (ddd, J = 1.2, 6.8, 7.4, 1H, Harom), 7.54 (dd, J = 1.2, 6.8, 1H, Harom), 7.63 (dd, J =
13
1.0, 6.8, 1H, Harom). C NMR (CDCl3, 10% DMSO-d6): δ 23.7 (NCH3), 25.9 (CH3), 26.3 (CH3), 75.7
(COH), 92.9 (COH), 122.4 (CH), 123.8 (CH), 128.9 (CH), 130.9 (CH), 132.4 (Cq), 146.0 (Cq), 167.6
(CON). MS (EI, 70 eV): m/z (%) 204 (M+-OH, 1), 188 (3), 175 (1), 162 (100), 148 (2), 133 (21), 105
(22), 77 (35), 52 (8). IR (CsI disc): ν (cm-1) 3506, 3226, 1674, 1473, 1426, 1185, 1069, 767. Anal. Calcd
for C12H15NO3: C 65.14, H 6.83, N 6.33. Found: C 65.39, H 6.85, N 5.98. 4-Hydroxy-2-methyl-
1
3a,4,5,7a-tetrahydroisoindole-1,3-dione (12). H NMR (CDCl3): δ 2.11 (m, 1H, CH2), 2.30 (m, 1H,
CH2), 2.86 (s, 3H, NCH3), 3.10 (dd, J = 4.9, 9.0, 1H, CH), 3.37 (m, 1H, CH), 4.18 (ddd, J = 4.4, 4.4, 6.7,
1H, CH), 5.76 (m, 1H, =CH), 5.83 (m, 1H, =CH), 8.02 (s, 1H, OH). 13C NMR (CDCl3): δ 24.5 (NCH3),
30.9 (CH2), 41.5 (CH), 44.0 (CH), 64.8 (COH), 121.3 (CH), 126.5 (CH), 176.7 (CO), 178.6 (CO). MS
(EI, 70 eV): m/z (%) 181 (M+, 15), 163 (14), 153 (8), 124 (8), 112 (10), 97 (10), 96 (100), 95 (52), 81
(21), 78 (15), 77 (14), 67 (21), 66 (18), 56 (8), 54 (8). 4-Hydroxy-4-methyl-2-pentanone (13). 1H NMR

13
(CDCl3): δ 1.19 (s, 6H, CH3), 2.12 (s, 3H, COCH3), 2.57 (s, 2H, COCH2), 3.72 (s, 1H, OH). C NMR
(CDCl3): δ 29.2 (CH3), 31.7 (COCH3), 53.8 (CH2), 69.4 (COH), 210.7 (CO).
ACKNOWLEDGEMENTS
This research project was financially supported by the Deutsche Forschungsgemeinschaft, the Fonds der
Chemischen Industrie, Degussa-Hüls AG, Bayer AG, and Merck KGaA. The authors thank Dr. Hans
Schmickler for the confirmation of compound 12 by NMR spectroscopic analysis.
REFERENCES
1. For early reviews, see: a) Y. Kanaoka, Acc. Chem. Res., 1978, 11, 407; b) Y. Kanaoka, J. Synth.
Org. Chem. Jpn., 1975, 33, 949.
2. a) M. Oelgemöller and A. G. Griesbeck, J. Photochem. Photobiol. C: Photochem. Rev., 2002, 3,
109; b) J. D. Coyle, 'Synthetic Organic Photochemistry', ed. by W. M. Horspool, Plenum Press,
New York, 1984, pp. 259-284; c) P. H. Mazzocchi, Org. Photochem., 1981, 5, 421.
3. a) P. H. Mazzocchi, S. Minamikawa, and P. Wilson, J. Org. Chem., 1985, 50, 2681; b) K.
Maruyama and Y. Kubo, J. Org. Chem., 1985, 50, 1426; c) P. H. Mazzocchi and L. Klinger, J. Am.
Chem. Soc., 1984, 106, 7567; d) Y. Kanaoka and Y. Hatanaka, Chem. Pharm. Bull., 1974, 22, 2205.
4. a) Y. Kanaoka and E. Sato, Chem. Pharm. Bull., 1978, 26, 989; b) H. J. Roth and G. Hundeshagen,
Arch. Pharm., 1976, 309, 58.
5. H. J. Roth and D. Schwarz, Arch. Pharm., 1976, 309, 56.
6. Y. Hatanaka, Y. Sato, H. Nakai, M. Wada, T. Mizuguchi, and Y. Kanaoka, Liebigs Ann. Chem.,
1992, 1113.
7. a) M. Freccero, E. Fasani, and A. Albini, J. Org. Chem., 1993, 58, 1740; b) Y. Kanaoka, K. Sakai,
R. Murata, and Y. Hatanaka, Heterocycles, 1975, 3, 719.
8. a) A. G. Griesbeck, W. Kramer, and M. Oelgemöller, Synlett, 1999, 1169; b) A. G. Griesbeck, A.
Henz, W. Kramer, J. Lex, F. Nerowski, M. Oelgemöller, K. Peters, and E.-M. Peters, Helv. Chim.
Acta, 1997, 80, 912.
9. A. G. Griesbeck and M. Oelgemöller, Synlett, 1999, 492.
10. a) S. Farcas and J.-L. Namy, Tetrahedron Lett., 2001, 42, 879; b) W. S. Ang and B. Halton, Aust. J.
Chem., 1971, 24, 851; c) K. Heidenbluth, H. Tönjes, and R. Scheffler, J. Prakt. Chem., 1965, 30,
204; d) G. Wittig and H. Streib, Liebigs Ann. Chem., 1953, 584, 1; e) G. A. Flynn, J. Chem. Soc.,
Chem. Comm., 1980, 862.
11. A. G. Griesbeck, W. Kramer, and M. Oelgemöller, Green Chem., 1999, 1, 205.

12. a) Y. Sato, H. Nakai, T. Mizoguchi, M. Kawanishi, Y. Hatanaka, and Y. Kanaoka, Chem. Pharm.
Bull., 1982, 30, 1263; b) Y. Sato, H. Nakai, T. Mizoguchi, M. Kawanishi, and Y. Kanaoka, Chem.
Pharm. Bull., 1973, 21, 1164.
13. U. C. Yoon, D. U. Kim, C. W. Lee, Y. S. Choi, Y.-J. Lee, H. L. Ammon, and P. S. Mariano, J. Am.
Chem. Soc., 1995, 117, 2698.
14. Yoon and Mariano recently described the formation of decarboxylation products in moderate yields
during the photolysis of 6 in acetonitrile: U. C. Yoon, C. W. Lee, S. W. Oh, and P. S. Mariano,
Tetrahedron, 1999, 55, 11997.
15. a) Y. Kanaoka, Y. Hatanaka, E. N. Deusler, I. L. Karle, and B. Witkop, Tetrahedron, 1985, 41,
5370; b) Y. Kanaoka, Y. Hatanaka, E. N. Deusler, I. L. Karle, and B. Witkop, Chem. Pharm. Bull.,
1982, 30, 3028.
16. a) Y. Kubo, T. Imaoka, C. Egusa, and T. Araki, Chem. Express, 1989, 4, 527; b) Y. Kubo, C. Egusa,
and T. Araki, Chem. Lett., 1985, 1213.
17. For further examples of this concept, see: a) A. G. Griesbeck and A. Bartoschek, Chem. Commun.,
2002, 1594; b) C. Schiel, M. Oelgemöller, J. Ortner, and J. Mattay, Green Chem., 2001, 3, 224; c)
A. Albini, M. Fagnoni, and M. Mella, Pure Appl. Chem., 2000, 72, 1321.
18. a) H. Schindlbauer, Monatsh. Chem., 1973, 104, 848; b) K. H. Hartmann and T. Troll, Tetrahedron,
1995, 51, 4655; c) P. Müller and H. Imogai, Tetrahedron: Asym., 1998, 9, 4419; d) D. A. A. Kidd
and F. E. King, Nature, 1948, 162, 776; e) G. B. Crippa and P. Gamlimberti, Gazz. Chim. Ital.,
1933, 63, 81; f) G. H. L. Nefkens, Nature, 1960, 185, 309; g) J. M. Chapman, G. H. Cocolas, and I.
H. Hall, J. Pharm. Sci., 1983, 72, 1344; h) M. Álvarez, D. Fernández, and J. A. Joule, Tetrahedron
Lett., 2001, 42, 315; i) P. Blaney, R. Grigg, Z. Rankovic, M. Thornton-Pett, and J. Xu, Tetrahedron,
2002, 58, 1719.
19. H.-R. Müller and M. Seefelder, Liebigs Ann. Chem., 1969, 728, 88.
20. The 1H NMR shifts of the sec-butyl side chains are differently influenced by the shielding effect of
the aromatic ring, see: A. G. Griesbeck, M. Oelgemöller, J. Lex, A. Haeuseler, and M. Schmittel,
Eur. J. Org. Chem., 2001, 1831.
21. H. Toi, Y. Yamamoto, A. Sonoda, and S.-I. Murahashi, Tetrahedron, 1981, 37, 2261.
22. Y. Kanaoka, Y. Migita, K. Koyama, Y. Sato, H. Nakai, and T. Mizoguchi, Tetrahedron Lett., 1973,
1193.
23. C. W. Rees and C. R. Sabet, J. Chem. Soc., 1965, 687.
24. R. P. Kreher, H. Hennige, F. Jelitto, and J. Preut, Z. Naturforsch., 1989, 44b, 1132.