Synthesis of disodium D (‐)‐6‐(2‐phenyl‐2‐sulfoacetamido‐1‐ 14 C) penicillanate (sulfocillln‐ 14 C) and 6‐(2‐isobutyl‐β,γ‐ 3 H 2 ‐sulfo‐2‐phenylacetamido‐1‐ 14 C) penicillanic acid (SP‐421‐ 3 H, 14 C)

The syntheses of disodium 6‐(2‐phenyl‐2‐sulfoacetamido‐1‐ 14 C) peniaillanate (IV) and 6‐(2‐isobutyl‐β,γ‐ 3 H 2 ‐sulfo‐2‐phenyl‐acetamido‐1‐ 14 C) penicillanic acid (XII) are described. The optically active D(‐)‐IV was obtained by the fractional crystallization of diastereoisomeric mixture which was prepared from phenylacetia acid‐1‐ 14 C (I). The compound double labelled with 3 H and 14 C, XII, was synthesized by the reaction of trimethylsilyl 6‐aminopenicillanate with 2‐isobutyl‐β,γ‐ 3 H 2 ‐ sulfo‐2‐phenylacetyl chloride‐1‐ 14 C (XI) which was prepared from isobutanol‐2,3‐ 3 H 2 and I. The overall radiochemical yields of XII, at the specific activities of 9 mCi ( 3 H)/mmole and 2 mCi ( 14 C)/mmole, were 34% yield based on isobutanol‐2,3‐ 3 H 2 and 17% yield based on I respeatively.