Synthesis and Synthetic Utilization of α-Functionalized Vinylphosphonates Bearing β-Oxy or β-Thio Substituents

• Published in: Journal of organic chemistry Vol. 63; no. 18; pp. 6239 - 6246
• Main Authors: Kouno, Ryoji, Okauchi, Tatsuo, Nakamura, Mitsuharu, Ichikawa, Junji, Minami, Toru
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 04.09.1998; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Organic; Physical Sciences; Science & Technology; ORGANIC-SYNTHESIS; ANTIBIOTICS; PHOSPHONATES; REAGENTS; BIOLOGY; CHEMISTRY; CARBANIONS; DITHIOACETALS
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo980467g

The β-hetero-substituted vinylphosphonates 1a−c on treatment with LDA or LTMP were readily lithiated at the α-position of the phosphono group, and the resulting α-lithiovinylphosphonates were trapped with various electrophiles to afford the corresponding α-functionalized vinylphosphonates 2−14 in 55−96% yields. The Friedel−Crafts reaction of α-(silyl)- or α-(germyl)phosphonoketene dithioacetals 2, 9, or 4 with acid chlorides gave α-acylated phosphonoketene dithioacetals 15−19 in 53−91% yields. The palladium-catalyzed cross-coupling reaction of β-ethoxy-α-(tributylstannyl)vinylphosphonate 13 with a variety of organic halides (R = acyl, allyl, aryl, etc.) provided β-ethoxy-α-substituted vinylphosphonates 21−26 in good to moderate yields. The palladium-mediated cross-coupling reaction of α-(iodo)vinylphosphonates 7 and 14 with terminal acetylenes afforded α-alkynylated vinylphosphonates 41−44 in 69−83% yields. Several α-functionalized β-hetero-substituted vinylphosphonates were applied to the synthesis of pyrazoles and an isoxazole possessing a phosphono function.