with ian coleman's bip39 (in console or whatever):

var mnemonics = { "english": new Mnemonic("english") };

var mnemonic = mnemonics["english"];

var phrase = mnemonic.generate(256);

var seed = mnemonic.toSeed(phrase);

var rootKey = libs.bitcoin.HDNode.fromSeedHex(seed);

var key = rootKey.derivePath("m/44'/1237'/0'/0/0");

var privateKeyHex = key.keyPair.d.toBuffer().toString('hex');

var publicKeyHex = key.getPublicKeyBuffer().toString('hex').slice(2,);

console.log({phrase: phrase, seed: seed, rootKey58: rootKey.toBase58(), key58: key.toBase58(), key: privateKeyHex, pub: publicKeyHex});