Patai S., Rappoport Z. 1997 The chemistry of functional groups. The chemistry of double-bonded functional groups / 0909 110

17. Syntheses and uses of isotopically labelled compounds

929

6. Synthesis of the [4-13C]oct-1-en-3-one (81)

The 13C label has been introduced66 into 81 by the sequence in equation 34. The compound 81 was needed to explain the MS mechanism of the fragmentation of the 2-hydroxy-1,3-butadiene.

*

LiA lH4

*

PBr3

*

CH3 (CH2 )3 COOH

CH3

(CH2 )3 CH2 OH

CH3 (CH2 )3 CH2 Br

Mg / ether

*

acrolein / ether

*

CH3 (CH2 )3 CH2 CH(OH)CH

CH2

CH3 (CH2 )3 CH2 MgBr

0

°C, 1 h, work-up

4 h

MnO2 , under argon

(34)

O

*

CH3 (CH2 )3 CH2 CCH

CH2

(81)89% yield

7.Synthesis of 13C- and 2H- labelled 2-phenylcyclododecanones

The commercially unavailable 2-phenylcyclododecanone-13C2 (82a and 82b) and perdeuterio-2-phenylcyclododecanone (83) have been synthesized67 69 to study the effects of magnetic isotopic substitution at the radical centres on the dynamics of flexible biradicals70,71. The compounds 82a and 82b have been synthesized in 8 steps as shown in equation 35. The 13C has been incorporated by treating 1,10-dibromodecane with two equivalents of K13CN (99% 13C).

O		O	O
Ph	Ph		C6 D5
* *		*	*

D2 1

(82a)

(82b)

(83)

Perdeuterio-2-phenylcyclododecanone, 83, has been prepared67 by H/D exchange between unlabelled 2-phenylcyclododecanone and excess of D2O, catalysed by D2- reduced PtO2 in the presence of alkaline catalyst (D2O2 and NaOD) prepared by adding 30 mg of Na2O2 to 20 ml of D2O at 0 °C over 1 hour. The exchange reaction proceeded at 240 250 °C in autoclave for 78 hours under 1000 psi of nitrogen (equation 36). Photochemical studies using 13C-labelled 82 and perdeuteriated derivatives of 2-phenylcyclododecanones 83 are in progress.

930

Mieczysław Ziełinski´ and Marianna Kanska´

KCN, 95% EtOH

KOH / H2 O

Br(CH2 )10 Br

NC(CH2 )10 CN

HOOC(CH2 )10 COOH

30 h reflux

80°C, 30 h reflux

20 h reflux

MeOH / conc. HCl

MeOOC(CH2 )10 COOMe

110 − 120°C, 12 h under argon

65% yield

Na / xylene, Me3 SiCl

OSiMe3

O

O

OSiMe3

O

OH

conc. HCl

+

15 min reflux

under argon

1 :

3

60% yield

O

3 h reflux

O

(35)

47% HI in H2 O / A c OH

Br

Br

Br2 (2 equiv.)/ AcOH (81%)

4 h RT

75% yield

Et2 O, −78 °C

RT (1 h)

Ph2 CuLi (2 equiv.)

O

O

Ph

Ph

+

(82a)

(1 : 1)

(82b)

17. Syntheses and uses of isotopically labelled compounds						931
O
Ph
	PtO2	/ D2 , Na2 O2	/ D2	O
					83, 75% yield (95% deuterium isotopic purity)
		250 °C, 78 h
						(36)

8. Synthesis of [1,3-13C2]-4-(2,6,6-trimethylcyclohexen-1-yl)buten-2-one (ˇ-ionone)

(84)

84, a simplified retinoid, a useful tool to probe by NMR the conformation of proteinbound retinoids used to treat skin diseases and as cancer chemopreventive agents72,73, has been synthesized by aldol condensation of [1,3-13C2]acetone with ˇ-cyclocitral, 85, catalysed by aqueous sodium hydroxide74 (equation 37).

						Me
Me	Me		Me		Me
	CHO					O
		1, 3-13 C2 -acetone					(37)
	10 % NaOH / H2O; 63 ° C, 9 days				Me	= 13 C
	Me
	(85)				(84) 73% yield, yellow oil

9. Synthesis of 1,3,4-thiadiazol-2-ylcyanamide-[5-14C], sodium fLY217896-[5-

14C]Nag 86-[5-14C], and 1,3,4-thiadiazol-2-ylcyanamide-[UL-13C3] sodium fLY217 896-[UL-13C3] Nag, 86-[UL-13C]

The new anti-influenza agent, LY217896, 86, active against both A and B strains of influenza75, has been 14C and 13C labelled76 to support the pre-clinical as well as clinical drug 86 metabolism and disposition studies and to facilitate the identification of metabolism of 86 in vivo.

(a)LY217896-[5-14C], 86a, has been obtained in five steps which involve the formylation of thiosemicarbazide 87 with formic[14C] acid in the absent of solvent as the first reaction step (equation 38).

(b)The uniformly labelled LY217896[13C], 86b-[UL-13C], has been synthesized76 for

metabolite identification utilizing potassium cyanide, cyanogen bromide and formic acid more than 99.5 isotopically enriched with 13C (equation 39).

10. Synthesis of 2,3-disubstituted [3-13C]naphthalenes and [9a-13C]naphthol[2,3-d]- 1,2,3-oxadiazole

2-Amino-3-hydroxy[3-13C]naphthalene, 88, has been obtained77 in seven steps starting with 2-(1,3-dioxolan-2-yl)-benzyl chloride and Na13CN (equation 40). The diazotation of the labelled amino compounds 88 followed by deprotonation provided [9a-13C]naphthol [2,3-d]-1,2,3-oxadiazole, 89 (equation 41).

932	Mieczysław Ziełinski´ and Marianna Kanska´

S

H2 N NHNH2

(87)

N

N

S

1. 85 °C, 0.5 h

+ H14 COOH							N N
			2. conc. H Cl, 85 ° C, 1h ; RT overnight
			3. 1N NaOH, work-up
									NH2
			overnight reflux						S
			PhCH2 Cl / MeCN						Bn
Bn					N		N
		BrCN / NaHCO3
	MeOH / H2 O, 50−60 °C, 2 h, work-up								NCN
						S
NH.HCl
									(38)
					work-up				A lCl3 / CH2 Cl2

	N	N		N	N
			NaOH / MeOH
		− +
			EtOA c
		NCN Na		S	NHCN
		S

		(86a)-[5-14 C]
		LY217896-[5-14 C]Na, 24.8% yield
	= 14 C label	r.purity ≥ 99.2%
		sp. act. 34.75 Ci / mg (5.14 mCi / mmol)

S

K13 CN + S

acetone

NH2 NH2 , MeOCH2 CH2 OH

KS13 CN

4 h reflux

130 °C, 2 h

H2 N

NHNH2

H13 COOH

as in eq. 38

Bn

N

N

N

N

BnCl / MeCN

NH.HCl

S

MeOH / H2 O

S

NH2

Br13 CN / NaHCO3

Bn

(39)

N

N

N

N

as in eq. 38

N13 CN

S

NH13 CN

S

= 13 C, Bn = PhCH2

(86b) - [13 C]

NaOH / MeOH

EtOA c

N

N

−

13

+

S

N

CN Na

(86) - as sodium salt

LY217896[UL-13 C]Na, 26.7% yield

17. Syntheses and uses of isotopically labelled compounds				933
O
	Na13 CN / MeCN		1. NaOH / H2 O, reflux
O			2. H+(pH 4-5), (40 % H3 PO4 )
	15-crown-5, 20 °C
			3. Et3 N
		CH2 CN

CH2 Cl

O		1. (EtO)2 P(O)CN, NCCH2 COOBu-t
	COOBu-t	DMF, 20 °C, 3 h	− +
		2. Work-up	CH2 COO Et3 NH
	CN		CN
	CF3 COOH / H2 O (trace)		(40)
	20 °C, 3 h

OH

COOMe

1.HCl / MeOH (anhydrous), 2 days under N2

2.H2 O (1 equivalent)

3. Work-up

OH

20 °C, 20 h NH3 / CH3 OH

CONH2

1. 3-(COOH)C6 H4 SO2 Cl, NaOH, H2 O 2. NaOCl / H2 O, 40 °C

OH

NH2

OH

(88)

+ −

N2 Cl

1. HCl, isopentyl nitrite

88
2. Work-up

OH

1.Basic A l2 O3 (4 % H2 O) (exclusion of light)

(41)

2. Work-up

N

N

O

(89) 16.6% yield, m.p. + 77°C (decomp.), storage at −20°C

The ˇ-13C-labelled naphthalenes obtained have been characterized by their 13C-NMR chemical shifts and 13C 13C coupling constants determined in CD3OD.

934	Mieczysław Ziełinski´ and Marianna Kanska´

11. Synthesis of [20,21-13C2]-pregnenolone (90)

90 labelled with 13C at C 20 and C 21 has been obtained78 by condensation of androst- 5-en-3ˇ-ol-17-one, 91, with K13CN and by Grignard reaction of nitrile derivative 92 with 13CH3MgI (equation 42). The location of carbon-13 was confirmed by 13C-NMR spectroscopy.

O

			CN
			OH
		K13 CN (99 atom %)
		EtOH, A c OH
	HO		t-butyldimethyl silyl chloride
	(91)
		CN	DMF, imidazole

Phosphorus oxychloride

Py, RT, 72 h

TBDMSiO

Pd / C (10 %), H2 (1 atm.)

TBDMSiO

		EtOA c, 7 h
	O		(42)
		CN

1.13 CH3 MgI, Et2 O, 40 h reflux under N2

2.0 °C, NH4 Cl/ H2 O, 2h

3.Work-up

			+ −	(92)
			1. (n-Bu)4 N F, THF, RT, 20 h
	2. Work-up
					O
	= Carbon − 13
			HO
				(90)

12. Synthesis of carbon-13 labelled 1-keto-7-methoxyoctahydrophenanthrene

The syntheses of carbon-13 labelled trans-tricyclic ketones 93 and 94 have been carried out79 via the cyanidation reaction of organoborane (equation 43). The isomerically pure trans-tricyclic ketones 93 and 94 were needed in connection with the undertaken synthesis

17. Syntheses and uses of isotopically labelled compounds

935

of carbon-11-labelled 17ˇ-estradiol and related hormones80,81.

O

MeO

1.CH2 CHCH2 MgBr

2.H2 O

3.H3 PO4

+ conjugated isomer

MeO

Thexylborane / THF, 0°C

B

MeO

1.NaCN

2.TFA A

3.NaOH / H2 O2

4. Purifications

	Me
O 1. (i-Pr)2 NLi	O
2. Me l
MeO	MeO
(93)	(94)
	= Carbon −13

(43)

13. Synthesis of 1,2,3,4,-tetrahydrocarbazole-9a-13C and carbazole-9a-13C

The title 13C-labelled heterocyclic compounds have been synthesized82 to understand better the coal liquification process83, Cyclohexanone-1-13C, 95, has been prepared through the sequence of reactions shown in equation 44. The carbonation of 96 at 78 °C gave 95 in 24 38% yield. At 8°C, the condensation of 95 with excess of Grignard

936	Mieczysław Ziełinski´ and Marianna Kanska´

reagent provided the alcohols 97, 98 and 99 and no 95 (equation 45). 100 and 101 have been prepared in 77% and 85% yields, respectively (equation 46), starting with 95. Several 13C-labelled compounds 100 have been synthesized also to study the effectiveness of hydrogen transfer solvents in coal liquification process84.

*

H3 O

+

Br(CH2 )5Br KCN

NC(CH2 )5CN

HOOC(CH2 )5COOH

Mg, Et2 O

O

1. 13 CO2

Ba(OH)2

(44)

BrMg(CH2 )5MgBr

2. H3 O+

(96)

(95)

O

HO

C5H11

HO

(CH2 )5COOH

1. BrMg (CH2 )5MgBr

+

H3 O+

(95)

(97)

(98)

(45)

HO

(CH2 )5

OH

+

(99)

1. A cOH, reflux

	95
		2. C6 H5NHNH2 , 1h reflux
		3. Work-up	NH

(100)

(46)

320 °C Pd / C

= Carbon-13

NH

(101)

17. Syntheses and uses of isotopically labelled compounds

937

14. Synthesis of [10-13C]bilirubin IX˛ (102)

102, the major product of haem degradation, is poorly excreted in the newborn. Its accumulation leads to damage of the central nervous system. The tracer kinetic studies in vivo with the use of radiolabelled bilirubin have, because of ethical reasons, not involved neonates. [10-13C]bilirubin has therefore been synthesized85,86 in overall 6% yields to elucidate the pathophysiological mechanism of bilirubin metabolism in humans. The total synthesis of 102 presented by equation 47 involves the Vilsmeier formylation of one of the dipyrrolic fragments using [1-13C]dimethyl amide. The penultimate dehydrohalogenation reaction has been complicated by side elimination reaction leading to 2,18 bridged with propane ether biliverolin derivative87, 105. For these reasons the route shown in equations 47a, b, c seems not to be the most propitious approach and the use of phenylselenylethyl groups as protected vinyl substituents88 has been suggested.

Cl

COOMe

t-BuOOC

Cl

t-BuOOC

Cl

t-BuOOC

Me Me

+

NH

AcOCH2

NH

COOBn

NiSMM

COOMe

Me Me

(47a)

NH

NH

COOBn

THF / Et3 N 10 % Pd / C, H2 , RT

COOMe

Me Me

NH

NH

COOH

(103)

NiSMM = Synthetic Mica Montmorillonite

with Incorporated Nickel

938		Mieczysław Ziełinski´ and Marianna Kanska´
MeOOC		Cl
	Me			Me
		+			1. NiSMM / CH2 Cl2
					2. Pd / C, Et3 N, THF / H2
BnOOC	NH	AcOCH2	NH	COOBu-t
				MeOOC	Cl
1. CH2 Cl2 / MeOH / p-toluene sulphonic acid monohydrate					Me	Me
	22 °C, 40 min (decarboxylation)

2.CH2 Cl2 / POCl3 , [1-1 3 C]DMF, 20 ° C, 1.5h (formylation)

3.Work-up

			HOOC	NH	NH	COOBu-t
MeOOC		Cl
		Me	Me
				103 TsOH, MeOH, CH2 Cl2
			19 °C, 18 h stir., work-up, HBr
	* NH	NH	COOBu-t
	O	(104)
Cl			Cl		HO	HO
					O	O
O	O					Cl
		Cl
NH	HN				NH	HN
		TFA , Br2	, N2	−
				Br	NH +
N	HN		0−5 ˚C , 1.5 h			HN
MeOOC		COOMe	MeOOC			COOMe

(47b)

Py, 3 % NaOH

2 h reflux, work-up

O	O
(2)	(18)
NH	HN
N	HN
MeOOC	COOMe

(105)