Androgenetic alopecia (AGA) is a transracial and cross‐gender disease worldwide with a youth‐oriented tendency, but it lacks effective treatment. The binding of androgen receptor (AR) and androgen plays an essential role in the occurrence and progression of AGA. Herein, novel proteolysis targeting chimera degrader of AR (AR‐PROTAC) is synthesized and integrated with dissolving microneedles (PROTAC‐MNs) to achieve AR destruction in hair follicles for AGA treatment. The PROTAC‐MNs possess adequate mechanical capabilities for precise AR‐PROTAC delivery into the hair follicle‐residing regions for AR degradation. After applying only once topically, the PROTAC‐MNs achieve an accelerated onset of hair regeneration as compared to the daily application of the first‐line topical drug minoxidil. Intriguingly, PROTAC‐MNs via single administration still realize superior hair regeneration in AGA recrudescence, which is the major drawback of minoxidil in clinical practice. With the degradation of AR, the PROTAC‐MNs successfully regulate the signaling cascade related to hair growth and activate hair follicle stem cells. Furthermore, the PROTAC‐MNs do not cause systemic toxicity or androgen deficiency‐related chaos in vivo. Collectively, these AR‐degrading dissolving microneedles with long‐lasting efficacy, one‐step administration, and high biocompatibility provide a great therapeutic potential for AGA treatment.

The first example of the preparation of α-diazo-β-hydroxy esters by the aldol-type condensation of aldehydes with ethyl diazoacetate using Et 3 N as base in the presence of magnesium iodide etherate [MgI 2 .(Et 2 O) n ] has been achieved in good to excellent yields at room temperature in CH 2 Cl 2 in 15-30 min. 5.93 (d, J = 2.5 Hz, 1H), 5H).Ethyl 2-diazo-3-hydroxy-3-(4-methoxyphenyl)propanoate (3b): 17 Yellowish oil; δ H 1.33 (t, J = 7.3 Hz, 3H), 3.00 (br s, 1H), 3.83 (s, 3H), 4.29 (q, J = 7.3 Hz, 2H), 5.88 (s, 1H), 6.93 (d, J = 7.0 Hz, 2H), 7.36 (d, J = 7.0 Hz, 2H). Ethyl 2-diazo-3-hydroxy-3-(o-tolyl)propanoate (3c): 16 Pale yellowish oil; δ H 1.29 (t, J = 7.1 Hz, 3H), 3.75 (br s, 1H), 3.84 (s, 3H), 4.25 (q, J = 7.1 Hz, 2H), 5.96 (d, J = 4.8 Hz, 1H), 6.91 (d, J = 8.2 Hz, 1H), 7.00 (m, 1H), 7.31 (m, 1H), 7.47 (d, J = 7.3 Hz, 1H). Ethyl 3-(4-chlorophenyl)-2-diazo-3-hydroxypropanoate (3d): 17 Pale yellowish oil; δ H 1.29 (t, J = 7.1 Hz, 3H), 3.69 (br s, 1H), 4.25 (q, J = 7.1 Hz, 2H), 5.87 (s, 1H), 7.34-7.38 (m, 4H).Ethyl 2-diazo-3-(4-f luorophenyl)-3-hydroxypropanoate (3e): 17 Yellowish oil; δ H 1.29 (t, J = 7.1 Hz, 3H), 3.52 (br s, 1H), 4.26 (q, J = 7.1 Hz, 2H), 5.89 (d, J = 1.25 Hz, 1H), 7.06-7.09 (m, 2H), 7.40-7.43 (m, 2H). Ethyl 2-diazo-3-hydroxy-3-(4-nitrophenyl)propanoate (3f): 17 Yellowish oil; δ H 1.28 (t, J = 7.1 Hz, 3H), 3.90 (br s, 1H), 4.26 (q, J = 7.1 Hz, 2H), 5.99 (s, 1H), 7.63 (d, J = 8.6 Hz, 2H), 8.21-8.24 (m, 2H). Ethyl 2-diazo-3-hydroxy-3-(4-(trifluoromethyl)phenyl)propanoate (3g): Pale yellowish solid, m.p. 52.3-53.1 °C (lit. 21 51-53 °C). δ H 1.29 (t, J = 7.2 Hz, 3H), 3.65 (br s, 1H), 4.27 (q, J = 7.2 Hz, 2H), 5.96 (s, 1H), 7.56 (d, J = 8.2 Hz, 2H), 7.65 (d, J = 8.2 Hz, 2H).Ethyl 2-diazo-3-hydroxy-3-(naphthalen-1-yl)propanoate (3h): 21 Pale yellowish oil; δ H 1.33 (t, J = 7.2 Hz, 3H), 3.72 (br s, 1H), 4.32 (q, J = 7.2 Hz, 2H), 6.64 (s, 1H), 7.50-7.56 (m, 3H), 7.83-7.95 (m, 4H).Ethyl 2-diazo-3-hydroxy-3-(thiophen-2-yl)propanoate (3i): 22 Yellowish oil; δ H 1.31 (t, J = 7.2 Hz, 3H), 3.39 (br s, 1H), 4.29 (q, J = 7.2 Hz, 2H), 6.12 (s, 1H), 7.02 (d, J = 3.9 Hz, 1H), 7.03-7.07 (m, 1H), 7.31 (d, J = 3.9 Hz).(E)-Ethyl 2-diazo-3-hydroxy-5-phenylpent-4-enoate (3j): 17 Yellowish oil. δ H 1.32 (t, J = 7.1 Hz, 3H), 2.87 (br s, 1H), 4.27 (q, J = 7.1 Hz, 2H), 5.46 (d, J = 5.3 Hz, 1H), 6.28 (dd, J = 5.6, 16.0 Hz, 1H), 6.82 (d, J = 15.6 Hz, 1H), 7.29-7.42 (m, 5H). Ethyl 3-cyclohexyl-2-diazo-3-hydroxypropanoate (3k): 17 Pale yellowish oil; δ H 0.92-1.31 (m, 8H), 1.45-1.80 (m, 5H), 2.0 (d, J = 12 Hz, 1H), 3.23 (br s, 1H), 4.19 (q, J = 7.02 Hz, 2H), 4.26 (d, J = 9.34 Hz, 1H). Ethyl 2-diazo-3-hydroxy-4,4-dimethylpentanoate (3l): 21 Pale yellowish oil. δ H 0.97 (s, 9H), 1.28 (t, J = 7.1 Hz, 3H), 2.94 (br s, 1H), 4.19-4.23 (m, 3H).

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