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Novel N -methylated valine-thiazole cyclic octa- and dodecapeptides are produced by cyclooligomerisation of a N -methylated- l -valine thiazole amino acid HCl in the presence of pentafluorophenyl diphenylphosphinate (FDPP).

Novel proline–thiazole based cyclopeptides were produced by cyclooligomerisation of an L-proline thiazole amino acid HCl in the presence of pentafluorophenyl diphenylphosphinate (FDPP) or diphenyl phosphorazidate (DPPA).

Methods are discussed for the stereoselective synthesis of the (R)-and (S)-enantiomers of the diosphenols ( 5 )–( 8 ) by utilizing the commercially available stereoisomers ( 9 ), ( 12 ), ( 23 ) and ( 25 ) of carvone and limonene, respectively, as chiral starting materials.

Syntheses of diosphenol (3), ψ-diosphenol (4), 6-hydroxydiosphenol (5) and 6-hydroxy-ψ-diosphenol (6), which are constituents of the essential oil from Barosma betulina Bartl. (mountain buchu), are discussed.

It is shown that bromoacetyl bromide can be utilized for the selective cleavage of ethers and acetals in high yields. With cyclic ethers and acetals as starting materials, cleavage products are produced with two strategically positioned bromo substituents which may be exploited for selective extention of the carbon chain.

Diosphenol (3) and ω-diosphenol (4), two constituents of the essential oil from the buchu plant, Borosma betulina (Bartl.), were utilized for the synthesis of the anulated 4-ylidenebutenolides (5) and (6).

Diosphenol (3) and ω-diosphenol (4), two constituents of the essential oil from the buchu plant, Borosma betulina (Bartl.), were utilized for the synthesis of the anulated 4-ylidenebutenolides (5) and (6).

It is shown that bromoacetyl bromide can be utilized for the selective cleavage of ethers and acetals in high yields. With cyclic ethers and acetals as starting materials, cleavage products are produced with two strategically positioned bromo substituents which may be exploited for selective extention of the carbon chain.