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The kinase DYRK1A is an attractive target for drug discovery programs due to its implication in multiple diseases. Through a fragment screen, we identified a simple biaryl compound that is bound to the DYRK1A ATP site with very high efficiency, although with limited selectivity. Structure-guided optimization cycles enabled us to convert this fragment hit into potent and selective DYRK1A inhibitors. Exploiting the structural differences in DYRK1A and its close homologue DYRK2, we were able to fine-tune the selectivity of our inhibitors. Our best compounds potently inhibited DYRK1A in the cell culture and in vivo and demonstrated drug-like properties. The inhibition of DYRK1A in vivo translated into dose-dependent tumor growth inhibition in a model of ovarian carcinoma.

Microwave‐assisted condensation of 1,3,‐2‐dioxaphosphinane 2‐oxide (1), paraformaldehyde and secondary amines including 5‐ and 6‐membered N‐heterocycles at 55°C gave cyclic aminomethylphosphonates (2), whereas an analogous reaction involving dibenzo[c.e][1,2]oxaphosphinane 2‐oxide (3) resulted in the corresponding aminomethyl‐2‐(2′‐hydroxybiphenyl)phosphinic acids (4) as a consequence of a hydrolytic ring opening following the condensation. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:207–210, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20387

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ABSTRACT:The ring enlargement

The inverse Wittig-type reaction of a series of 2,4,6-trialkylphenyl cyclic phosphine oxides 3, 5, 7, 9, 11, 13, 15, 18 and 20 and dialkyl acetylenedicarboxylate giving b-oxophosphoranes 4, 6, 8, 10, 12, 14, 16, 19 and 21, respectively, can be accomplished in a convenient way under microwave conditions. At 150°C, the MWassisted reaction is more efficient and becomes 50-fold faster as compared to the thermal transformation. A further advantage is that the 2,5-dihydrophosphole moiety of the 2,4,6-triisopropylphenyl derivative 3 does not undergo double-bond rearrangement and that the 2,4,6-trimethylphenyl substrates 11 and 13, otherwise inactive in the reaction under discussion, could also be converted to b-oxophosphoranes 12 and 14. A series of new products 4Bb, 12, 14, 16b, 19 and 21 have been made available.A novel reaction has been discovered by us, in which the interaction of 1-(2,4,6-trialkylphenyl)cyclic phosphine oxides 1 and dialkyl acetylenedicarboxylates (DAAD) react to form the corresponding b-oxophosphoranes 2 that can be regarded to be stabilized phosphonium ylides (Scheme 1). 1-3 As the reaction of the P=O group and the triple bond forms a P=C and a C=O bond, the novel transformation can be regarded to be an inverse Wittig-type reaction. 4 Reactivity of the b-oxophosphoranes 2 was in accord with the structure established by spectroscopy. 5 Depending on the substituents, the transformation requires heating at 150°C for 7-14 days. An additional problem is the inevitable polymerization of DAAD that makes the reaction less efficient and complicates the work-up.In this paper we describe an efficient accomplishment of the P=O + -C≡C-reaction under microwave conditions.Other advantages of the microwave synthesis are also discussed and the reactions extended to new model compounds.We found that the reaction time of the 1 → 2 conversion at 150°C decreased dramatically under microwave conditions. In contrast to the 7-14 days required for the completion applying traditional heating, the microwave-assisted reaction was complete after three to six hours of irradiation. This means an average 50-fold rate acceleration. Moreover, polymerization of the DAAD was suppressed increasing the efficiency and facilitating the purification.Reaction of the 1-(2,4,6-triisopropylphenyl)-2,5-dihydro-1H-phosphole oxide 3 with dimethyl acetylenedicarboxylate (DMAD) was studied in detail (Table 1). It was surprising that in contrast to the result of the thermolysis at 150°C for eight days, 2 the rearrangement of the double bond in the product 4a was only partial. Hence, b-oxophosphorane 4Ba predominated over 4Aa. It was more appropriate to use the components 3 and DMAD as neat, in the absence of toluene. An increase of the excess of DMAD decreased the reaction time and the extent of double bond rearrangement. The use of three to five equivalents of DMAD is the optimum. In a closed system (under 2-3 bar pressure), the reaction is somewhat faster than in an open vessel, the extent of the isomerization is, however, more considerable. Fr...