a-stannyl-organolithium compounds to have been prepared by direct metalation (H/Li exchange)[5!The sulfur-free carbonyl compounds (7), (S), and ( 9 ) have been prepared by thioacetal hydrolysis or Raney nickel desulfurization oftheadducts ( 4 a ) . Yields: 71,66, and 60%, respectively; 'H-NMR (cc14): Si(CH3)3 singlets at 6=0.2, 0.23, and 0.25, respectively; CH3 in ( 8 ) : 0.95 (d, 7 t h ) ; IR: 1710, 1640; 1745, 1635; and 1735, respectively. Received: August 8. 1974 [Z 112 IE] German version: Angew. Chem. 57, 37 (1975) CAS Registry numbers: ( l a ) . R=CH,, ; ( I b ) , R=CH,,; R=n-C,H,, 53369-99- 6; ( I b ) , R=C,H,, 53370-00-6; (21, n=2,930-30-3; (Z), n=3, 930-68-7; (2). n=4. 1121-66-0; (5), n=3, 53369-93-0; (6), n=3. E ' = E 2 = H , 53369-94-1; ( 6 ) , n=3, El=CH,, E 2 = H , 53369-95-2; (71, 53369-96-3;(8). 53369-97-4; (9) 53369-98-5; ( 4 ) .

Alkylation of oxazolin-5-ones 1 with alkyl halides/ethyldiisopropylamine in dipolar aprotic solvents yields 4,4-disubstituted oxazolin-5-ones 2, which are cleaved with HCl/acetic acid to give a-amino acids 3. The introduction of cycloheptatrienyl residues with tropylium perchlorate/triethylamine in benzene is described. Oxazolin-5-ones may be considered as nucleophilic acyl equivalents. This is demonstrated by alkylation of 4-isopropyl-2-phenyl-2-oxazolin-5-one (1 b) to give 4-isopropyl-4-(2-nitrobenzyl)-2-phenyl-2-oxazolin-5-one (20 which may be transformed into isopropyl 2-nitrobenzyl ketone (12). Zur Einfuhrung einer Verzweigung in a-

Trisubstituierte 4‐Allyl‐2‐oxazolin‐5‐one 2 gehen beim Erhitzen auf 230°C unter Abspaltung von Kohlendioxid in 2,6‐disubstituierte Pyridine 7 über. Der Reaktionsmechanismus wird diskutiert.

A new method for the chain elongation of carboxylic acids leads to ketones under very mild conditions. Organometallic intermediates are avoided. The 2‐phenylglycine used as “vehicle” does not appear in the final product.

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