The stereochemical course of reduction of derivatives of 4-0XO a-amino acids 3 to give cis-and trans-y-substituted ~-aminobutano-4-lactones 9 and 10 using a range of hydride reducing agents is reported. Although reduction with sodium boranuide (sodium borohydride) in protic solvents proceeds with low stereoselectivity, use of triethylsilane-boron trifluoride-diethyl ether gives good selectivity in favour of the cis-isomer, provided that the 4-substituent is phenyl. Moderate to excellent stereoselectivity in favour of the trans-isomer may be obtained by using L-Selectride@ in tetrahydrofuran. The presence of an additional stereogenic centre at C-5 completely overwhelms the effect of the a-centre. Applications of this method in approaches to the synthesis of clavalanine, erythro-4-hydroxyornithine and (+) -bulgecinine are described.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

No abstract

No abstract

Thermal and Photochemical Reactions of η5-Cyclopentadienyl( naphthoyl)(dicarbonyl)iron Complexes with Alkynes: Formation of Benzindenones and Dihydropentalenones.-2-Naphthoylchloride shows a similar reactive behavior as the 1-isomer ( II), the analogous product to (V) being (VII). Both (VI) and (VII) have space group P21/n, Z = 4. -(BUTLER, I. R.; CHARLAND, J.-P.; ELLIOT, J. L.; HOUDE, J. JUN.; LINDSELL, W. E.; MCCULLOUGH, K. J.; PRESTON, P. N.; RETTIE, A.