An organocatalytic enantioselective synthesis of δ‐lactone‐fused 4‐chromanones was demonstrated using 1‐(2‐hydroxyaryl)‐1,3‐butanedione and α,β‐unsaturated aldehydes in the presence of the Jørgensen‐Hayashi catalyst. The reaction proceeded through a Michael addition/cycloketalization/hemiacetalization sequence, and the resulting hemiacetals were oxidized into the corresponding lactone derivatives in a one‐pot manner. The desired fused O,O‐ketal tricyclic lactone motifs containing three contiguous chiral centers were obtained in excellent chemical yields (up to 97%) and with high stereoselectivities (up to >20:1 dr and up to 95% ee).

中文翻译：

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对映体有机催化合成δ-内酯融合的4-色曼酮

在Jørgensen-Hayashi催化剂的存在下，使用1-（2-羟基芳基）-1,3-丁二酮和α，β-不饱和醛证明了δ-内酯融合的4-苯并二氢醌的有机催化对映选择性合成。反应按照迈克尔加成/环缩酮化/半缩醛化顺序进行，然后将生成的半缩醛以单锅方式氧化为相应的内酯衍生物。所需的包含三个连续手性中心的稠合的O，O-缩酮三环内酯基序以优异的化学收率（高达97％）和高的立体选择性（高达> 20：1 dr和高达95％ee）获得。