Synthesis of C-ring-functionalized A-ring-aromatic trichothecane analogs

Synthesis of 6-alkyl analogues of the 1-azabicyclo[4.3.0]nonan-2-one system by a strategy of geminal acylation and Beckmann rearrangement

“…Geminal acylation using 7 has been exploited in the syntheses of a number of natural products and other structurally interesting molecules. 6, 14 In the present study, simple compounds resembling 5 were envisaged with R being methyl, isobutyl, phenyl and terminally substituted alkyl. It seemed that this last type might be prepared by cleavage of a substituted ring after geminal acylation, to give a spirocyclic diketone, and Beckmann rearrangement.…”

“…The combined aqueous layers were extracted with CH 2 Cl 2 (3 × 50 ml), and the combined organic layers were dried over anhydrous MgSO 4 . The solvent was evaporated under vacuum to yield 13 (1.87 (11), 43 (18), 41 (28), 39 (14), 32 (21), 29 (17) and 28 (100).…”

“…For 14: pale yellow liquid; ν max (film)/cm Ϫ1 2958 (broad), 1764 and 1722; δ (12), 125 (14), 112 (100), 111 (37), 107 (15), 81 (13), 55 (31), 43 (22) (11), 173 (24), 155 (57), 154 (13), 153 (12), 145 (16), 111 (97), 101 (100), 83 (22), 69 (52), 57 (19), 55 (45), 45 (26), 43 (33) and 41 (36).…”

“…Following the procedure for 20, NH 2 OSO 3 H (23.4 mg, 0.207 mmol) and 25 (25.5 (25), 194 (15), 154 (11), 152 (12), 125 (28), 124 (65), 110 (30), 97 (23), 96 (31), 86 (22) (20), 152 (28), 138 (25), 125 (57), 110 (59), 100 (14), 97 (33), 96 (61), 69 (100), 55 (31) and 41 (54).…”

Formation of 2,2-disubstituted 1,3-cyclopentanediones from ketals with 1,2-bis(trimethylsilyloxy)cyclobutene

“…This material was subjected to chromatography twice (5%) to provide 6-rnethylspiro[4,5]decane-l,4-dione (1 16 mg, 30%) as a pale yellow oil: ir v,,,: 1715 cm-'; 'H nmr 6: 2.90-2.48 (4H, m), 1.95-1.17(9H,m),0.75(3H,d,J=6.3H~);'~~nmr6:217. 4 …”