Organic Chemistry of Explosives

Homocubanes 75

Marchand and co-workers^20 synthesis of 5,5,9,9-tetranitropentacyclo[5.3.0.0^2 ,^6 .0^3 ,^10 .0^4 ,^8 ]

decane (52) required the dioxime of pentacyclo[5.3.0.0^2 ,^6 .0^3 ,^10 .0^4 ,^8 ]decane-5,9-dione (49) for

the incorporation of the four nitro groups. Synthesis of the diketone precursor (48) was achieved

in only five steps from cyclopentanone. Thus, acetal protection of cyclopentanone with ethylene

glycol, followed byα-bromination, and dehydrobromination with sodium in methanol, yielded

the reactive intermediate (45), which underwent a spontaneous Diels–Alder cycloaddition to

give (46). Selective acetal deprotection of (46) was followed by a photo-initiated intramolecular

cyclization and final acetal deprotection with aqueous mineral acid to give the diketone (48).

Derivatization of the diketone (48) to the corresponding dioxime (49) was followed by con-

version of the oxime groups togem-dinitro functionality using standard literature procedures.

O

EtCO

O

O

OH

OH

MeO OMe

Cl Cl

Cl

Cl

OH

OH

MeO OMe

O

HO

NOH

HON

NO 2

59

NO 2

O 2 N

O 2 N

O 2 N

O 2 N O 2 N

O 2 N

O 2 N

NO 2

NO 2

NO 2

NO 2

NO 2

O

O

NaOAc, 70 %

(^5354) 55 OCEt
NOH 57 O 56 OH
60 61
Li, tBuOH, THF
liq. NH 3 , -33 °C
92 %
EtCO 2 H,
H 2 SO 4 , 150 °C
51 %
Na,
MeOH
100 %
PCC, CH 2 Cl 2
46 %
NH 2 OH.HCl,
(CF 3 CO) 2 O,
90 % H 2 O 2 ,
NaHCO 3 , urea
CH 3 CN, 35 %

1. NaOH


2. K 3 Fe(CN) 6 ,
   NaNO 2 ,65%
   
   
   1. NaOH
   
   
   2. K 3 Fe(CN) 6 ,
      NaNO 2 ,62%
   
   
   
   

58

Figure 2.14

Triketone (57), a key intermediate in the synthesis of 4,4,7,7,11,11-hexanitropentacyclo

[6.3.0.0^2 ,^6 .0^3 ,^10 .0^5 ,^9 ]undecane (61) (D 3 -hexanitrotrishomocubane), has been synthesized in-

dependently by both Marchand and co-workers,^17 and Fessner and Prinzach^23. Marchand and

co-workers^17 prepared the trioxime (58) from the corresponding triketone (57). Oxidation

of (58) with peroxytrifluoroacetic acid in acetonitrile provides a direct route to the trinitro

derivative (59) in 35 % yield, this yield reflecting an efficiency of 70 % for the oxidation of

each oxime group. Subsequent oxidative nitration of (59) with sodium nitrite and potassium

ferricyanide in aqueous sodium hydroxide yields the targetD 3 -hexanitrotrishomocubane (61).