Adamantane acetylation

The oxime of 1-acetyl adamantane (15) was added to acetylene (initial acetylene pressure 13 atm) to afford the corresponding 0-vinyl oxime 16 (Equation (4)) (08TL4362). The latter upon heating (DMSO, 120 °C, 1 h) rearranged to 2-(l-adamantyl)pyrrole (17), 1-acetyl adamantane (18) and adamantane (19) (6 3 1 mass ratio), the yield of the pyrrole 17 being 83% (based on 1-acetyl adamantane (18) consumed) (Equation (5)). 

Adamantan 2-(N-Methyl-hydroxy-amino)- E16a, 141 (R—NO 4-R —M), 160 (Nitron-Red.) 3-Aza-bicyclo 4.4.0]decan 3-Acetyl-XI/1, 716... 

The acceleration of substitution reactions with azides using ultrasound techniques (Scheme 31) has not yet been investigated in detail. Activated primary halides react with trimethylsilyl azide (TMS-A) under particularly mild and absolutely neutral conditions (Scheme 31). Secondary and tertiary cyclic halides were treated with TMS-A/SnCU in CH2CI2 or CHCI3 to yield the corresponding azido compounds." Very impressive results with yields of about 90% were in this case reported in the adamantane and diamantane series." High solubility in organic solvents is also noticed with acetyl azide, which, prepared in situ, has also been used for azide syntheses. The scope of this reaction has still to be determined, however." Hassner noticed nearly quantitative yields of azides when alkyl halides (or tosyl-ates) were treated with polymeric quaternary ammonium azides. 

Acetyladamantanes. Acetyl groups are introduced into the bridgehead positions of adamantane when the hydrocarbon and biacetyl are submitted to oxidation conditions [02-Co(OAc)2 in HOAc, 60°]. 

Kashman and Benaiy reported the successful ring closure of the hicyclic alcohol S9 by lead tetraacetate (without or with iodine added) to the N(6)-acetyl-2-oxa-6-aza-adamantane (41). 

Reaction of the syn-exo-diepoxide 20 (9-oxa) with methylamine under pressure gave 61%of N(6)-methyl-4 8 -dihydroxy-2-oxa-6-aza-adamantane (79), which by subsequent acetylation yielded the diacetate 80. 

The oxidation of substituted adaman-tanes has been studied in detail by Miller [21, 22] and Mellor [23-25]. Cpe in a divided cell produces two types of products by substitution at the tertiary carbon atom substitution of hydrogen for acetamide with retention of the substituent X in the adamantane molecule [substituent X (yield in %) H (90), Cl (91), F (65), CH3 (91), CO2CH3 (64), CN (41)1 and substitution of X for acetamide [Br (89), CH2OH (37),C0CH3 (44), oh (41),0CH3 (58)1 [22]. Cleavages of 1-acetyl-, 1-bromo... 

The preparation of 4-alkoxybicyclo [2.2.2] octan-2-ones from 4-acetyl-1-methoxy-l-cyclohexene by a novel cycloisomerization of 1,3-disubst. adamantanes by an exceptionally easy ring closure from suitable unsatd. cycloketones , and of cubane derivatives by an elegant three-step procedure have been reported. 

Figure 66. Co(OAc)2 catalyzed acetylation of adamantane with diacetyl...

No reaction takes place in the absence of O2 with Co(ll) or in the presence of O2 with Co(III), which points to a cobalt-dioxygen complex (probably Co 02) as key intermediate. It reacts with diacetyl to produce acetyl free radicals, which in turn are converted to acetylperoxyl radicals via reaction with 02. The latter are capable of abstracting an H-atom from adamantane, which constitutes the hydrocarbon activating step (Figure 67). 

Aza-adamantanes.—1-Aza-adamantanes are easily available in a convenient two-step synthesis from a-pinene (Scheme 83)." The synthesis is dependent on the serendipitous discovery that solvomercuration-demercuration of a-pinene with acetonitrile in the presence of mercuric nitrate followed by in situ boro-hydride reduction led not to the expected allylic amide but instead to azabicy-clo[3,3,l]nonene which is readily converted into aza-adamantane by reaction with formaldehyde. Rearrangement of A-chloro-N-acetyl-l-aminoadamantane... 

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