Hachiohji, Tokyo 192-0397 Japan</=> Japan Society for the Promotion of S=ience (DC1), Ichibancho, Chiyoda-ku, Tokyo 102-8471, Japan</=pan> PRESTO (Precursory Research for Embr=onic Science and Technology), Japan Science and Technology Agency, 4- 1-8 H=ncho Kawaguchi, Saitama, Japan J. Am. Chem. Soc., Article ASAP